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YOGYAKARTA, JUNE 2008
MM DARISSALAM
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1. Angkatan ‘71
Teknik Geologi UGM(8 years + 3 months)
2. Oil Industry1. 24+ years in 7 oil coy’s.)
2. 7 years Petroleum Consultant
3. Terakhir
PSC Tropik Energi
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References & Sources of Presentation Materials
• Shlumberger : Oil Field Review, Short Courses & Promotions slides,Manuals, Publications, etc.
• Baker Hudges : Publications & Manuals• Halliburton : Published slide and books• Publications & In-house Training materials from: TOTAL, Chevron,
Texaco etc.• AAPG & SPE journals & slides bank• Literatures:
– Development Geology P Dikey – Development Geology Reference Manuals AAPG – Petroleum Engineering Hand Books: Amyx, Craft, Campbel, etc.
– Log Analysis Books : Batteman, Dewan, Helander etc – Petroleum Reservoir, Stratigraphy and Tectonic Books : …..
Note : Due to the rush preparation of these presentation slides, the sources and references are not noted yet.
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PRESENTATION OUTLINEI.
INTRODUCTION
II. WELLSITE GEOLOGYIII.
LOG INTERPRETATION
IV.
WELL TESTING
V. PETROLEUM RESERVOIRENGINEERING
VI.
CORRELATIONS & MAPPING
VII. RESERVES ESTIMATIONVIII.
RESERVOIR SIMULATION
IX.
PLAN OF DEVELOPMENT
X. RESERVOIR MANAGEMENT & PROJECT ECONOMIC
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I. INTRODUCTION
1.
COURSE OBJECTIVE
2.
UPSTREAM PETROLEUM INDUSTRY &DEVELOPMENT GEOLOGIST
3. PETROLEUM GEOLOGYa.
SOURCE ROCKS & MATURATION
b.
HYDROCARBON MIGRATION
c.
CAP ROCKS / SEALS
d.
STRUCTURE / TRAP
e.
RESERVOIR ROCKS & FLUID
4.
DRILLING
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COURSE OBJECTIVECOURSE OBJECTIVE
•• To introduce participants the generalTo introduce participants the generalpetroleum industrial processes andpetroleum industrial processes and
especially during oil/gas fieldespecially during oil/gas field
development phasedevelopment phase
•• To provide participants the basic ofTo provide participants the basic of
petroleum development/productionpetroleum development/productiongeology as entry provisions intogeology as entry provisions into
upstream petroleum industryupstream petroleum industry
•• Sharing knowledge andSharing knowledge and ““silaturachmisilaturachmi””
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PETROLEUM INDUSTRY SECTORSPETROLEUM INDUSTRY SECTORS
Concession Acquiring&
EXPLORATION
DEVELOPMENT&
PRODUCTION
TRANSPORTATION
OIL REFINEMENT /
PROCESSING
UPSTREAMUPSTREAM
DOWNSTREAMDOWNSTREAM
•HIGH RISK•HIGH REWARD•HIGH INVEST.
•LOW RISK•LOW REWARD•HIGH INVEST.
24803
Transporting PetroleumTransporting Petroleum
Oil FieldOil Field
Oil FieldOil Field
PipelinePipeline RefineryRefinery
PipelinePipeline
Railroad Tank CarsRailroad Tank Cars
Mobil
Tank TruckTank Truck
ConsumersConsumers
Industrial Customers
IndustrialCustomers
Local DistributorLocalDistributor
Mobil
TankerTanker
Offshore PlatformOffshorePlatform
24803
Refining PetroleumRefining Petroleum
GasolineGasoline
Fuel GasFuel Gas
Kerosene – Jet FuelKerosene – Jet Fuel
Heating OilHeatingOil
Lubricating OilLubricatingOil
Residual Products– Asphalt, Heavy Fuel Oil
Residual Products– Asphalt,Heavy Fuel Oil
Crude Oil VaporCrude OilVapor
Liquid Crude OilLiquid Crude Oil
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EXPLORATION PHASE DEVELOPMENT PHASE
G&G STUDYSEISMIC SURVEY
DRILLINGS
PLAN OF DEVELOPMENT
G&GR STUDYDEV. DRILLING, WORKOVER
PRODUCING, EOR etc.AD’L SEISMIC
MARKETING
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PRODUCTON
TIMEEXPLORATION
DEVELOPMENT SECONDARY RECOVERY ABANDONMENT
CONVENTIONAL
Development & Operation GeoscientistsDevelopment & Operation Geoscientists
ExplorationGeoscientists
ExplorationGeoscientists
GeophysicistsGeophysicists
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SYNERGIC TEAM N UPSTREAM OIL INDUSTRY
Geologists & Reservoir Engineer
P r o d
u c t i o n
E n g
i n e e r
Surface Prod. Eng.,Processing Eng.,Transportation
Eng. & Marketing
DEVELOPMENT GEOLOGIST
•Reservoir Characterization•Reserves Estimation•Reservoir Optimization
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Development Geology = Production Geology = ReservoirGeology
Hybrid discipline: geology on the field and reservoir scale.
Principal Responsibilities of The Development Geologist(DG): Estimation of Volumetric Reserves Justifying drilling & workover options to improve recovery Plan and acquisition geological data while drilling & production Providing a framework for maximum financial return for his
company
DG requires good knowledge of many disciplines : Structural Geology.
Stratigraphy and sedimentology. Reservoir engineering. Drilling methods and engineering. Petrophysics.
Laboratory for rock and fluid Seismology. Petroleum Economics and management.
Petroleum Development Geology
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What is a petroleum exploration &
development geologists?EXPLORATION GEOLOGIST DEVELOPMENT GEOLOGIST
DISCOVERS HYDROCARBONRESERVES
Technical and functional expertiseon regional geology
(basin /
petroleum system analysis, tectonicand stratigraphy), geophysical(acquisistion, processing and
interpretation), computer and othertechnical
DEVELOPES & PRODUCESHYDROCARBON
Technical and functional expertiseon reservoir geology, log
interpretation, detailed correlation& mapping of flow unit, basicpetroleum engineering, drilling, field
operation, computer and othertechnical
Additional: Financial awareness –
understanding the business. Project
management, team work, achieving results skills Interpersonal,communication, serving skills
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WHY COMPANY SHOULD HAVE A DEVELOPMENT GEOLOGIST
Engineers, Geologists andGeophysicists don’t just specialize in
different fields, they think in differentways.
There is a communication problem:the development geologist must beable to bridge the gap.
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Geophysical Processing
E&P Management
DrillingEngineering
ReservoirEngineering
Geoscience
Bridging the Disciplines Enhanced operational efficiencies through new,
multi-disciplinary workflows
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responsibility of the DG in
PREDEVELOPMENT EVALUATION
After field discovery :
• Evaluate field forreserves, well
placement anddesign criteria.
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responsibility of the DG in
DEVELOPMENT DRILLING
DG is responsible for:
– Initiating developmentwell recommendations
– Decide what reservoirgeological data shouldbe collected and preparethe geological prognosis
– Monitoring these wellsduring drilling
– Adjusting developmentplans as wells are drilled
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responsibility of the DG in
WELL SURVEILLANCE
• Generally handled by the reservoir engineer (RE)
• However, when performance is not as expected or whenremedial work is required (workover, stimulation &optimization) the DG inputs geological constraint.
•RE & DG work together toevaluate unusual reservoirperformance.
•RE & DG then makeremedial recommendations
responsibility of the DG in
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responsibility of the DG in
FIELD STUDIES
One of the most importantroles of the DG :
• Re-evaluation of old fieldsand recognition of newopportunities in these
fields.• This role will become
increasingly important in
the future as reservesdecrease.
• Improved oil recovery as
well as enhance oilrecovery.
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CONCLUSION• Development geology is not only a
rewarding, but a lucrative field for thesmall and independent operator.
• In the future, this field (whichrequires skills in many oil/gas fields)will become more important as
reserves decline.• The bottom line in all petroleum
exploitation is financial andeconomic evaluations require input
from many disciplines: the DG musthave these skills.
• The most important ability isRESERVES ESTIMATION andRESERVOIR OPTIMIZATION.
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a. SOURCE ROCKS & MATURATIONb. HYDROCARBON MIGRATION
c. CAP ROCKS / SEALS
d. STRUCTURE / TRAP
e. RESERVOIR ROCKS
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Petroleum System ProcessesPetroleum System Processes
•• GenerationGeneration -- Burial of source rock to temperature andBurial of source rock to temperature and
pressure regime sufficient to convert organic matter intopressure regime sufficient to convert organic matter into
hydrocarbonhydrocarbon
•• MigrationMigration -- Movement of hydrocarbon out of the sourceMovement of hydrocarbon out of the source
rock toward and into a traprock toward and into a trap
•• AccumulationAccumulation -- A volume of hydrocarbon migrating intoA volume of hydrocarbon migrating intoa trap faster than the trap leaks resulting in ana trap faster than the trap leaks resulting in an
accumulationaccumulation
•• PreservationPreservation -- Hydrocarbon remains in reservoir and isHydrocarbon remains in reservoir and is
not altered by biodegradation ornot altered by biodegradation or ““waterwater--washingwashing””
•• TimingTiming -- Trap forms before and during hydrocarbonTrap forms before and during hydrocarbonmigratingmigrating
P t l S t PP t l S t P
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Petroleum System ProcessesPetroleum System Processes
AccumulationAccumulation
SourceSourceRockRock
120° F120° F
350° F350° FGenerationGeneration
MigrationMigration
Seal RockSeal Rock
Reservoi
Rock
Reservoi
Rock
OilOil
WaterWater
Gas CapGasCap
EntrapmentEntrapment
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The principal zone of oil formation
during the thermal generation ofpetroleum hydrocarbons
•
If the temperature is too
low, the organic materialcannot transform intohydrocarbon.
• If the temperature is toohigh, the organic materialand hydrocarbons are
destroyed.
HYDROCARBON MIGRATION
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HYDROCARBON MIGRATION
• Hydrocarbon migration takes place in two stages:
– Primary migration - from the source rock to a porous rock. This is a
complex process and not fully understood. It is probably limited to afew hundred metres.
– Secondary migration - along the porous rock to the trap. This occurs
by buoyancy, capillary pressure and hydrodynamics through acontinuous water-filled pore system. It can take place over largedistances.
CAP ROCK
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CAP ROCK
• A reservoir needs a cap rock.
• Impermeable cap rock keeps the
fluids trapped in the reservoir.• It must have zero permeability.• Some examples are:
– Shales. – Evaporites such as salt or anhyhdrite. – Zero-porosity carbonates.
TRAPSThe reservoir form depends on the
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TRAPS
GENERAL
pdepositional environment and post depositionalevents such as foldings and faulting.
The criteria for a structure is that it must have:•Closure, i.e. the fluids are unable toescape.•Be large enough to be economical.
STRUCTURAL TRAPS
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•• Tilted faultTilted fault--block trapsblock traps are formed where the upward flow of theare formed where the upward flow of thepetroleum is prevented by impermeability along the fault planepetroleum is prevented by impermeability along the fault planeand by an overlying cap or seal: common in the North Sea.and by an overlying cap or seal: common in the North Sea.
STRUCTURAL TRAPS
Structural traps are formed where the space forStructural traps are formed where the space for
petroleum is limited by a structural featurepetroleum is limited by a structural feature
•• AnticlinalAnticlinal trapstraps areareformed by foldingformed by foldingin the rocks.in the rocks.
•• UnconformityUnconformitytrapstraps areare
generated wheregenerated whereanan erosionalerosional breakbreakin thein the stratigraphicstratigraphicsuccession issuccession isfollowed byfollowed by
impermeableimpermeablestrata.strata.
SALT DOME TRAP
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SALT DOME TRAP• Salt Dome traps are caused when "plastic" salt is forced upwards.
• The salt dome pierces through layers and compresses rocksabove. This results in the formation of various traps:
• In domes created by formations pushed up by the salt.
• Along the flanks and below the overhang in porous rock abuttingon the impermeable salt itself.
STRATIGRAPHIC TRAPS
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STRATIGRAPHIC TRAPS
StratigraphicStratigraphic
traps are trapstraps are traps
created by thecreated by the
limits of thelimits of the
reservoir rockreservoir rock
itself, withoutitself, without
any structuralany structuralcontrol.control.
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PETROLEUM RESERVOIR ROCKSPETROLEUM RESERVOIR ROCKS
DEFINITIONDEFINITION
•• A body of porous and permeable rockA body of porous and permeable rock
containing oil and gas through whichcontaining oil and gas through which
fluid may move toward recoveryfluid may move toward recoveryopening under the pressure existing oropening under the pressure existing or
that may be applied. (that may be applied. (AmyxAmyx, 1960), 1960)
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TYPE OF RESERVOIR ROCKS
Sedimentary:
Clastic ; eg. Sandstone, Conglomerate
Non Clastic ; eg. Limestone, Evavorite.
Igneous:Plotunic ; e.g. Granite
Volcanic ; eg. Basalt
Volcanic Clastic : eg Tuff, Breccia.
Metamorphic:
eg. Marble, gneiss, quartzite, slate etc.
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Reservoir Rocks
Reservoir rocks need two properties to be successful:
1. Pore spaces able to retain hydrocarbon.
2. Permeability which allows the fluid to move.
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DEFINITION OF POROSITY
b
mab
b
p
V
VV
V
VPorosity
−=
POROSITY SANDSTONES
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POROSITY SANDSTONES• The porosity of a sandstone depends on the packing arrangement
of its grains.• The system can be examined using spheres.
In a Rhombohedral packing, the pore
space accounts for 26% of the totalvolume.
In practice, the theoretical value is rarelyreached because:
a) the grains are not perfectly round, and
b) the grains are not of uniform size.
With a Cubic packingarrangement, the pore space fills47% of the total volume.
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POROSITY AND GRAIN SIZE
• A rock can be made up of small grains or
large grains but have the same porosity.
• Porosity depends on grain packing, not thegrain size.
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PORE-SPACE CLASSIFICATION
• Total porosity, φt =
• Effective porosity, φe =
• Very clean sandstones : φt = φe
• Poorly to moderately well -cemented intergranular
materials: φt ≈ φe
• Highly cemented materials and most carbonates:
φe < φt
Volume Bulk
Space PoreTotal
Volume BulkSpace Pore cted Interconne
G S S
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DIAGENESIS• The environment can also involve subsequent alterations of the
rock such as:
• Chemical changes.
• Diagenesis is the chemical alteration of a rock after burial. Anexample is the replacement of some of the calcium atoms inlimestone by magnesium to form dolomite.
• Mechanical changes - fracturing in a tectonically-active region.
CARBONATE POROSITY TYPES
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CARBONATE POROSITY TYPES
Interparticle porosity: Each grain is
separated, giving a similar pore spacearrangement as sandstone.
Intergranular porosity: Pore space iscreated inside the individual grainswhich are interconnected.
Intercrystalline porosity: Produced by
spaces between carbonate crystals.
Mouldic porosity: Pores created by the
dissolution of shells, etc.
• Carbonate porosity is very heterogeneous. It is classified into a
number of types:
CARBONATE POROSITY TYPES
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CARBONATE POROSITY TYPES
Fracture porosity:
• Pore spacing created by thecracking of the rock fabric.
Channel porosity:
• Similar to fracture porositybut larger.
Vuggy porosity:
• Created by the dissolutionof fragments, butunconnected.
CARBONATE POROSITY
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CARBONATE POROSITY
• Intergranular porosity is called "primaryporosity".
• Porosity created after deposition is called
"secondary porosity".
• The latter is in two forms: – Fractures
– Vugs.
FRACTURES
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FRACTURES
• Fractures are caused when a rigid rock is strained beyond itselastic limit - it cracks.
• The forces causing it to break are in a constant direction,
hence all the fractures are also aligned.• Fractures are an important source of permeability in low
porosity carbonate reservoirs.
VUGS
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VUGS
• Vugs are defined as non-connected pore space.
• They do not contribute to the producible fluid total.
• Vugs are caused by the dissolution of solublematerial such as shell fragments after the rock hasbeen formed.
• They usually have irregular shapes.
PERMEABILITY
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PERMEABILITY
• The rate of flow of a liquid through aformation depends on:
– The pressure drop. – The viscosity of the fluid.
– The permeability.
• The permeability is a measure of the ease atwhich a fluid can flow through a formation.
• The unit of measurement is the Darcy.• Reservoir permeability is usually quoted in
millidarcies, (md).
DARCY LAW
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DARCY LAW
• K = permeability, in Darcies.
• L = length of the section of rock, in centimetres.
• Q = flow rate in centimetres / sec.
• P1, P2 = pressures in bars.
• A = surface area, in cm2.
• µ = viscocity in centipoise.
PERMEABILITY AND ROCKS
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PERMEABILITY AND ROCKS
In formations with large grains, the permeability ishigh and the flow rate larger.
PERMEABILITY AND ROCKS
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PERMEABILITY AND ROCKS
• In a rock with small grains the permeability is lessand the flow lower.
• Grain size has no bearing on porosity, but has a
large effect on permeability.
ANISOTROPY
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ANISOTROPY
Horizontal Permeability
Vertical Permeability
The permeability in the horizontal direction is controlled by thelarge grains.
The permeability in the vertical direction is controlled by the
small grains
1≤ H
V
K
K 1≤
H
V
K
K 1≤
h
V
K
K
CLASTIC
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RESERVOIRS
•
Sandstone usually hasregular grains; and isreferred to as agrainstone.
•
Porosity : Determined
mainly by the packing andmixing of grains.
•
Permeability : Determined
mainly by grain size andpacking, connectivity andshale content.
• Fractures may bepresent.
CARBONATE
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RESERVOIRS
• Carbonates normally havea very irregular structure.
• Porosity: Determined bythe type of shells, etc. andby depositional and post-
depositional events(fracturing, leaching, etc.).
• Permeability: Determinedby deposition and post-deposition events,fractures.
• Fractures can be very
important in carbonatereservoirs.
LIMESTONES
DOLOMITES
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© Schlumberger 1999
DRILLING Christmas
Pipeline toFlow
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DRILLING
☯Making a hole or well tomake access intoreservoir and toproduce hydrocarbon(oil & gas) fromsubsurface.
☯ To collect thesubsurface geologicaland reservoirdata/information for
further hydrocarbonexploration as well asdevelopment.
ChristmasTree Process
and
Storage
SurfaceCasing
IntermediateCasing
ProductionCasing
CompletionFluid
CementPacker
Cement
Cement
Tubing
WellFluids
Oil or Gas Zone
Perforations
OIL EXTRACTING HISTORY
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OIL EXTRACTING HISTORY
In the earliest day of oilproduction, oil wascollected from surfaceseepages.
Mine shafts were dug tomake a well (like waterwell in Java) to produce
shallow oil.
In the early 19th century
peoples developed cabletool drilling
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CABLE TOOLDERRICK
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JACK UP UNIT
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JACK UP UNIT
A jack-up unit
is a barge with legs that can be
lowered or raised. The barge is towed
to the
drilling location with its legs in the raisedposition. Once in position, the legs are lowered.When they reach the sea-bed, the barge's bodyis hoisted above the water, creating a stable
drilling platform. The length of the legsdetermines the depth of water in which a jack-up barge can be
used. They can generally be
used in up to 100 meters of water. Jack-upbarges are widely employed in the relativelyshallow waters of the North Sea's Southernbasin.
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SEMI-SUBMERSIBLE RIG
A semi-submersible drilling rig
is normally a self-
propelled working platform supported by verticalcolumns on submerged pontoons. By varying theamount of ballast water in the pontoons, the unitcan be
raised or lowered in the water.
A semi-submersible vessel is normally held inposition by up to eight very large anchors, or bydynamic positioning: computer controlleddirectional propellers to keep the vessel stationary
relative to the sea-bed, compensating for wind,wave or current.
Semi-submersibles can drill in water depths to 300meters or more all year round.
SETTING UP THE RIG
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•
Depending upon the remoteness of thedrill site and its access, equipment may betransported to the site by truck,helicopter or barge.
•
Some rigs are built on ships or barges forwork on inland water where there is nofoundation to support a rig (as in marshesor lakes).
• Once the equipment is at the site, the rigis set up. Here are the major systems ofa land oil rig:
–
Power System
– Mechanical System–
Rotating Equipment
–
Casing
–
Circulation System
–
Derrick
– Blowout Preventer
RIG EQUIPMENT
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OWER AND MECHANICAL SYSTEMS
• Mechanical system - drivenby electric motors – hoisting system - used for
lifting heavy loads; consists ofa mechanical winch(drawworks) with a largesteel cable spool, a block-and-tackle pulley and a receivingstorage reel for the cable
– turntable - part of the drillingapparatus
• Power System – large diesel engines - burn
diesel-fuel oil to provide themain source of power – electrical generators -
powered by the diesel enginesto provide electrical power
RIG EQUIPMENT
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HE DERRICK
• Derrick - support structure: holdsthe drilling apparatus – tall enough to allow new
sections of drill pipe to beadded to the drilling apparatusas drilling progresses
• Blowout preventers and Rams -high-pressure valves (located
below the rotary table or on thesea floor) – seal the high-pressure drill
lines and relieve pressurewhen necessary to prevent a
blowout (uncontrolled gush ofgas or oil to the surface, oftenassociated with fire)
– Can shut off either the annularspace (between pipe and well)
or the complete hole.
RIG EQUIPMENT
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OTATING EQUIPMENT
• Rotating equipment - used for rotarydrilling – swivel - large handle that holds the weight of
the drill string; allows the string to rotate and
makes a pressure-tight seal on the hole – kelly - four- or six-sided pipe that transfers
rotary motion to the turntable and drill string – turntable or rotary table - drives the rotating
motion using power from electric motors – drill string - consists of drill pipe
(connected sections of about 30 ft / 10 m)and drill collars (larger diameter, heavierpipe that fits around the drill pipe and placesweight on the drill bit)
• Drill bit(s) - end of the drill that actually cuts
up the rock; comes in many shapes andmaterials (tungsten carbide steel, diamond)that are specialized for various drilling tasksand rock formations
• Casing - large-diameter concrete pipe thatlines the drill hole, prevents the hole fromcollapsing, and allows drilling mud tocirculate
RIG EQUIPMENT
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HE MUD CIRCULATION PROCESS
• There's more to drilling than simplyrotating the bit.
• Fluid is circulated while the drillingproceeds.• Powerful pumps move the fluid down
the pipe, through the bit and back to
the surface, carrying the cuttings andother debris with it.• Thus, on a rotary rig (unlike the cable
tool), drilling can be continuous as
stopping to bail the cuttings is nolonger required.
• The drilling mud also stabilizes thewalls of the hole.
RIG EQUIPMENT IRCULATION SYSTEM
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• Circulation system - pumps drillingmud under pressure through the kelly,rotary table, drill pipes and drill collars
– pump - sucks mud from the mud pitsand pumps it to the drilling apparatus
– pipes and hoses - connects pump todrilling apparatus
– mud-return line - returns mud from hole
– shale shaker - shaker/sieve thatseparates rock cuttings from the mud
– shale slide - conveys cuttings to thereserve pit
– reserve pit - collects rock cuttingsseparated from the mud
– mud pits - where drilling mud is mixedand recycled
– mud-mixing hopper - where new mud ismixed and then sent to the mud pits
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RIG EQUIPMENT THE
DRILLSTRING
CONTROLLINGTHE WEIGHT ON THE BIT
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The weight is held partly bythe hook etc. If not, the drill
bit wouldn’t turn! Collars areadded to the drill string toadd more weight
Hence the driller can controlthe weight on the bit byadding/ removing collars orby raising/lowering theswivel tackle.
TYPE OF BIT - Which bit?
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•Largest bit is used first, decreasing with depth•For each formation & depth have a particular set of
jet sizes, gallons per minte, pump strokes per minte,
minimum annular velocity (speed mud returns at tokeep the hole clean), bit hydraulic horsepower.•Hence the hydraulic and bit programs work intandem to most efficiently drill the well giving best
cost per foot, drilling time, minimum down time.
CONTINUING THE DRILLING PROCESS
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• Drilling continues in stages: – Drill – run and cement new casings, then drill again.
• When the rock cuttings from the mud reveal the oil sandfrom the reservoir rock, the final depth may have beenreached.
• At this point, the drilling apparatus is removed from thehole and perform several tests to confirm this finding: – Well logging - lowering electrical and gas sensors into the hole
to take measurements of the rock formations – Drill-stem testing - lowering a device into the hole to measure
the pressures, which will reveal whether reservoir rock has beenreached
– Core samples - taking samples of rock to look for characteristicsof reservoir rock
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DRILLING PROBLEMS
Other Drilling Problemsther Drilling Problems
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WELL COMPLETION TYPE
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PRODUCINGSAND
1.1. OpenholeOpenhole CompletionCompletion
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pp pp
OpenholeOpenhole completioncompletion
merupakanmerupakan penyelesaianpenyelesaian
sumursumur dimanadimana casingcasingdipasangdipasang hanyahanya sampaisampai didi
atasatas zonazona produktif produktif
(interest zone).(interest zone). JadiJadi sumursumurdiproduksidiproduksi dengandengan kondisikondisi
terbukaterbuka didi sepanjangsepanjang zonazona
produksiproduksi..
CASING SHOE
PACKER
CEMENT
CASING
PRODUCTIONSTRING
P R O D U C I N G
L A Y E R
2. Liner Completion
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Ada dua model penyelesaian sumurmenggunakan Liner Completion :
1. Screen Liner Completion
Casing diset sampai di atas zona
produksi yang kemudiandigabungkan dengan kombinasi linerdan screen yang tidak disemen diseluruh permukaan zona produksi
2. Perforated Liner Completion
Metode penyelesaian sumur denganmelakukan pemasangan liner dandisemen pada zona produktif yang
kemudian dilaksanakan pelobangan(perforated) pada zona-zona yangpaling produktif
CASING SHOE
PACKER
CEMENT
CASING
PRODUCTION STRING
LINER HANGER
SLOTTED LINER
LINER SHOE
OIL SAND
P R O
D U C I N G L
A
Y E R
PRODUCTION3. Perforated Casing Completion3. Perforated Casing Completion
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Perforated casingcompletion adalah
penyelesaian sumurdengan menutup semuazona produktif denganmenggunakan casingdan disemen kemudiandilakukan perforasi(pelubangan) pada
daerah-daerah produksidi lubang sumur
CASING SHOE
PACKER
CEMENT
CASING
STRING
PERFORATION
OIL SAND
P R O D U C I N G L
A Y E R
g p
PRODUCING WELLCOMPLETION
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THE MAST (CHRITMAST-TREE)
Setelah
pemboran
dinyatakan
berhasil
dan
mendapatkan
minyakatau
gas, maka
di
kepala
sumur
dipasang
chritmas
tree yang
didefinisikan
sebagai
rangkaian
dari valve dan fitting yangdigunakan
untuk
control produksi
dan disambungkan dengan bagianatas
tubing head. Pertama
kali
christmas
tree digunakan
untuk
tekanan
aliran
rendah
dan
menengah
dari
suatu
sumur,
dimana
rangkaian
dari
tees,
elbows, nipples, valve yang dibeli
secara terpisah dan dirangkaikan jadi satu di lokasi.
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• Wellsite geology is hybrid of
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appllied geology on oil and gas welldrilling, its study rock cuttings andwireline logs from oil and gas wellsto determine what rock formationsare being drilled into and how thedrilling should proceed.
• Wellsite Geologist is geologist incharge on data acquisition from oil
and gas well drilling operation.They are required to monitor vitaloperations during the course of thewell, make sure that the wellprogram are carried out perform
formation evaluation activities toensure the well is drilled andevaluated in the most safe, efficientmanner, and cost-effective. Theyalso liaise with drilling engineers,
petroleum engineers and mudlogging geologist during the courseof ro ects. JOB SPIRIT
JOB PORPOSES
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TEAM WORK IN RIG SITE1. COMPANY MAN
2. WELLSITE GEOLOGIST
3. DRILLING ENGINEER
4. TOOLPUSHER & RIG CREW
5. MUDLOGGING CREW
6. MUD & CHEMICAL ENGINEER & CREW7. CEMENTING ENGINEER & CREW
8. WIRELOGGING ENGINEER & CREW
9. TESTING ENGINEER & CREW
10. OTHER SERVICES ENGINEERS & CREW11. SUPPORTING CREW
THE RULERSHE RULERS
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N RIG SITEN RIG SITECOMPANY MAN
LEADER &DECISION MAKER
DRLG ENG.
•CHEMICAL & CEMENTING•DIRECTIONAL
•WELL COMPLETION
TOOL PUSHER•DRILLING
•RIG MAINTENANCE
GEOLOGIST•MUD LOGGING
•MWD & LOGGING•WIRELINE LOGGING
•CORING
•WELL TESTING
IN SMALL COMPANY
CO. MAN ALSO AS
DRLG. ENG.
WELLSITE GEOLOGIST ENERAL DUTIES & RESPONSIBILITIES1. Supervision of “Formation Evaluation”
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contractors (Mud Logging Geologists,MWD Logging Engineers, WirelineLogging Engineers, Coring and WellTesting Personnel)
2. Logistics concerning the formationevaluation contractors and theirequipment
3. All safety aspects for the well andpersonnel during these evaluationoperations
4. Quality control of all evaluation resultsand logs prior to accepting the data orlogs from those contractors
5. Providing relevant correlation and welldata to those contractors during theiroperations
6. Checking all reports and logs from theevaluation contractors prior to sendingthem to oil company offices
WELLSITE GEOLOGIST ENERAL DUTIES & RESPONSIBILITIES
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7. Monitoring and supervising thecollecting, processing and dispatchingof formation evaluation samples
8. Safe-guarding the collection, storageand transmission of information andreports at the wellsite
9. Wellsite interpretation of the formation
evaluation data10. Checking and occasionally approving
and signing of service reports andinvoices of the formation evaluation
contractors11. Keeping the drilling superintendent
and operations geologist fullyinformed of all formation evaluation
operations
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WELL PROGNOSIS AND ROSPECT DESCRIPTION
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Wellsite Geologist should becompletely familiar with all
aspects of the drillingprognosis. Particular attentionshould be paid to any sectionswhich may require geological
decisions.1. Determination of Primary and
Secondary Objectives
2. Determination of Casing Points3. Detection of Overpressured
Intervals
4. Detection of Lost CirculationZones
5. Correlation and Detection of Marker Horizons
6 Determin tion of Geologic B sement or Economic B sement
WELL PROGNOSIS AND ROSPECT DESCRIPTION
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6. Determination of Geologic Basement or Economic Basement7. Selection of Logging Run Intervals8. A complete set of correlation logs and reports should be compiled
9. Near by well’s mudlogs, lithlogs and wireline logs should be usedas sources of information
REGIONAL GEOLOGY PREPARATIONFOR WELLSITE GEOLOGIST
to anticipate if it should deviate from the prognosis
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to anticipate if it should deviate from the prognosis
• Nature and depth of basement within thebasin
• Geologic age of the section
• Depositional environments and expectedlithologies
• Tectonic setting within the basin
• Formation pressure anomalies• Hydrocarbon occurrences within the basin
• Basin correlations
RIGSITE INFORMATION SOURCES USES
Wireline Logging Unit
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Wireline Logging Unit• VSP Used to “look ahead”, formation top confirmation• RFT Fluid sampling, Pressure determination, Oil/Water/Gas
gradients• ResistivityWater Saturation, Porosity, Hydrocarbon evaluation
• Density & Neutron Lithology confirmation, Correlation, Porosity,Overpressure detection, Gas/Oil contacts
• Sonic Porosity, Mechanical properties, Overpressure• Dipmeters Structure, Well trajectory, Facies analysis,
Sedimentology
• Sidewall Cores Biostratigraphy, Geochemistry, Lithologyconfirmation, Hydrocarbon evaluation
Mud-Logging Unit
• Cuttings Geochemistry, Lithology, Correlation, Density, Calcimetry,Hydrocarbons, Shale Factor (C.E.C.), Hole Stability, Bit Condition• Hydrocarbons Total gas, Chromatograph, Gas Ratios, Connection
gases, Trip gases, Oil shows• Gases CO2, H2S
• Engineering Dxc, Torque, Drill Rate, Formation Pressures
RIGSITE INFORMATION SOURCES USES
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MWD/FEMWD unit data• Directional Borehole Trajectory (MWD), Dogleg
Severity• Gamma Ray Lithology Determination, Shale
Content,• Resistivity Correlation, Hydrocarbon Evaluation,
Pressure Indication, Sw Estimations• Density Lithology, Correlation, Pressure Indication,Gas/Oil Contact
Others• Coring Biostratigraphy, Reservoir analysis,
Porosity, Permeability
WELLSITE GEOLOGIST RESPONSIBILITIES
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IN WIRELINE LOGGING OPERATION
To ensure satisfactory results, the Wellsite
Geologist will be responsible for:
Safety aspects during logging operations
Organizing personnel and equipmentlogistics
Logging Quality Control and Dataaccuracy
Carry out quick look log interpretation and
reporting to operation geologist.
QUICK LOOK LOG ANALYSIS
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Existence and depth of known markers.
Top and bottom of each reservoir interval
Gross & net thickness for each reservoirinterval
Type of hydrocarbon and hydrocarbon/watercontacts
Average and range of calculated porosityand water saturation values for each interval
Rw in the clean, water-bearing formations
Propose well test intervals
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WELLSITE GEOLOGIST TEAM N MUDLOGGING UNIT
• THE TEAM MUDLOGGING CREW:
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• THE TEAM MUDLOGGING CREW:• MUDLOGGING GEOLOGIST (MUDLOGGER)• PRESSURE ENGINEER / DATA ENGINEER• SAMPLE CATCHER
• MUDLOGGING GEOLOGIST – CUTTING & CORE DESCRIPTION, HYDROCARBON SHOW,
POROSITY ETC.
• PRESSURE ENGINEER & DATA – RECORD, MONITOR & ANALYSE THE DRILLING PARAMETERS
SUCH AS ROP, RPM, WOB, TORQUE, – MUD DATA: MUD TANK LEVEL (MUD LOOS & GAIN), MUD
WEIGHT IN/OUT, TEMPERATURE IN/OUT – MUD PUMP DATA : CAPACITY, EFICIENCY, VOLUME IN ETC.
• SAMPLE CATCHER – COLLECT AND PREPARE SAMPLE FOR MUDLOGGING
GEOLOGIST
MUDLOGGING UNIT
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TYPE OF SAMPLE
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• DRY SAMPLE – obtained from the washed samples collected from the 80-mesh
sieve. A heat source is used for drying purposes.
– Several precautions when drying samples are:• DO NOT oven dry oil-based mud samples• Do not over-dry samples, because they will burn (the burning can be
mistaken for oil staining)• Clay samples should not be oven dried - only air dried
• WET SAMPLE – collected at the shale shaker. Normally the drilling fluid is not
rinsed off.
• GEOCHEMICAL SAMPLE – These samples require special treatment. – A bacteriocide (i.e. Zepharin Chloride) is necessary to prevent the
growth of bacteria which can form additional gas. The samples are
normally sealed at the wellsite, and shipped separately.
CUTTINGS DESCRIPTION
Each lithology should be accurately described and
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Each lithology should be accurately described, andthat observations recorded in the following order:
a. Rock Type g. Sorting
b. Classification h. Luster
c. Color i. Cementation/Matrix
d. Hardness/Induration j. Visual Porosity
e. Grain Size k. Accessories/Inclusions
f. Grain Shape l. Oil Show Indications
Usually major oil company has own cutting description manual and its standar legend.
COMPARISON CHARTS FOR VISUAL ESTIMATION OFPERCENTAGE COMPOSITION
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PARTICLE SHAPE OUNDNESS VS SPHERICITY
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EVALUATION OF HYDROCARBON SHOWS
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GAS SHOW• EQUIPMENTS
– chromatograph
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– CO2 detection – H2S detection (in exploration & rich sulfur basin)
– total gas detectors that monitor for N, various sulfides andH may also be used
• The amount of gas recorded is dependent upon manyvariables, including;
– Volume of gas per unit volume of formation – Degree of formation flushing – Rate of penetration – Mud Density and Mud Viscosity
– Formation pressure – Gas trap efficiency – Gas detector efficiency – Variability of mud flow rate
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GAS SHOW EVALUATION• True Zero Gas :
– The value recorded by the gas detectors when pure air is passed over the detection block
(generally done during calibration). To ensure a stable zero mark, the detectors should be zeroedprior to drilling, at casing points, logging points, etc.
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• Background Zero Gas : – The value recorded by the gas detectors when circulating, off-bottom, in a clean, balanced bore
hole. Any gases monitored will be from contaminants in the mud or from gas recycling. This valueis the baseline from which all gas readings are referenced for the striplog and mud log, but not
plotted on the logs. This value will change with respect to changes in the mud system (addingdiesel) and hole size, and should be re-established periodically.
• Background Gas : – This is the gas recorded while drilling through a consistent lithology. Often it will remain constant,
however, in overpressured formations this value may show considerable variation. This is the gasbaseline which is plotted on the striplog and mud log.
• Gas Show : – This is a gas reading that varies in magnitude or composition from the established background. It
is an observed response on the gas detector and requires interpretation as to the cause. Not allgas peaks are from drilled formation, some may occur as post-drilling peaks.
• Connection Gases : – Gas peaks produced by a combination of near-balance/ under-balanced drilling and the removal of
the ECD by stopping the pumps to make a connection. They are often an early indicator of drillingoverpressured formations. These should be noted, but not included as part of a total gas curve.
• Trip Gases : – Gas peaks recorded after circulation has been stopped for a considerable time for either a bit trip
or a wiper trip. As with connection gases, substantial trip gases can indicate a near balancebetween the mud hydrostatic pressure and the formation pressure, they should be recorded but notincluded as part of a total gas curve.
WELL 123
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SAMPLE:
MUD LOGGING
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SAMPLE:MUD LOGGING
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Mud-logging Geologist Corner
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WIRELINE LOGIRELINE LOG
1. WHAT IS WELL LOGGING:1. WELL LOG IS A CONTINUOUS RECORD OF MEASUREMENT MADE IN
BORE HOLE RESPOND TO VARIATION IN SOME PHYSICAL
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BORE HOLE RESPOND TO VARIATION IN SOME PHYSICALPROPERTIES OF ROCKS THROUGH WHICH THE BORE HOLE ISDRILLED.
2. TRADITIONALLY LOGS ARE DISPLAY ON GIRDED PAPERS SHOWN INFIGURE.
3. NOW A DAYS THE LOG MAY BE TAKEN AS FILMS, IMAGES, AND INDIGITAL FORMAT.
2. WIRELINE LOGGING IS PERFORMED WITH A SONDE LOWERED INTO THEBOREHOLE OR WELL
3. 2 TYPES OF WIRELINE LOGGING :1. OPEN HOLE LOGGING2. CASED HOLE LOGGING
4. INTERPRETATION METHODS1. QUALITATIVE2. QUANTITATIVE
1. MANUAL2. COMPUTERIZED
LOG INTERPRETATIONOG INTERPRETATIONIS A PROCESS OF USING WELL LOGS TO
EVALUATE THE CHARACTERISTIC OFFORMATION :
TOP SAND
LITHOLOGY
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• STORAGE CAPACITY porosity,
fluid saturations and net pay thickness • FLUID PROPERTIES density, fluid
type, fluid contacts, API gravity,water resistivity & salinity,
temperature, GOR • GEOLOGICAL SETTING
structural/dip/fracture, geologic environtment, facies characteristic,top/bottom reservoir,
heterogeneities, distribution • PRODUCTIVITY : permeability, water
cut, GOR and rate (estimated)
TOP SAND
SAND THICKNESS
SAND PROSITYPERMEABILITYFLUID SATURATIONS
LOG INTERPRETATIONLOG INTERPRETATIONLog interpretation should provide answers to questions on:
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LOG INTERPRETATIONOG INTERPRETATIONIS PART OF RESERVOIR CHARACTERIZATION PROCESS WHICH
SHOULD BE INTEGRATED WITH THE FOLLOWING SURVEYAND ANALYSIS:
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– DRILLING OPERATION LOGS:
• CUTTING ANALYSIS, MUD ANALYSIS, DRILLING DATA COLLECTION(PRESSURE, GAS READING, PENETRATION RATE ETC.) ANDANALYSIS.
– CORRING & CORE ANALYSIS :
• SIDE WALL CORE & FULL HOLE CORE
• VISUAL LITHOLOGY DESCRIPTION, HYDROCARBON SHOWS,POROSITY, PERMEABILITY, FORMATION FACTOR, SATURATIONETC.
– PRODUCTIVITY TEST :
• RFT, MDT, DST, PRODUCTION TESTS
– GEOLOGY & GEOPHYSICAL :
• SURFACE GEOLOGY, SEISMIC SURVEY & INTERPRETATION ETC.
RESERVOIR CHARACTERIZATIONESERVOIR CHARACTERIZATION
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LOGGING UNITSOGGING UNITS
LOGGING UNIT CONTAINS:• logging cable• winch to raise and lower
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winch to raise and lowerthe cable in the well
• self-contained 120-voltAC generator
• set of surface controlpanels
• set of downhole tools
(sondes and cartridges)• digital recording system
Open Hole Logging :
1. The traditional wirelinelogging
2. Logging While Drilling3. Logging on drill pipe
WELLELLLOGGINGOGGING
Logging Job Sequences :
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Rig-up logging unit Check Tool and system
Wellsite Geologist (WG) willperform system & tool qualitycontrol
Safety meeting
Tool run in hole
The system is on but never beused for log interpretation
Pull-out and logging WG is the witness, checks the
logging speed and quality.
WG has authority to stop, refuseand re-logging when necessary
Rig-down the logging unit. Print the result WG signs the services ticket
containing type of services andcharges
LOGGING UNIT
SONDE / TOOL
WIRELINE
SAMPLE :SAMPLE : OPEN HOLE LOGOPEN HOLE LOGSP, GR, AIT, SONIC,SP, GR, AIT, SONIC,
DENSITY & NEUTRONDENSITY & NEUTRON
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SP
GR DT
AIT
RHOZ
NPHI
1. SP SPONTANEOUS
POTENTIAL LOG2. GR GAMMA RAY LOG3. ELECTRICAL LOG
INDUCTION, LATERAL,SPHERICAL FOCCUSS, MICRO
LATERAL ETC4. NEUTRON LOG CNL, SNP5. DENSITY LOG LDT6. SONIC LOG BHC
7. OTHERS : FMI (DIPMETER &IMAGING), NMRI (NuclearMagnetic Resonance Immaging,TEMPERATURE LOG, CALLIPERLOG, ETC.
S PP
SP results from electriccurrents flowing in the
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currents flowing in thedrilling mud.
There are three sources ofthe currents, twoelectrochemical and oneelectrokinetic.
Membrane potential -
largest. Liquid - junction potential.
Streaming potential -
smallest.
SP LOG READINGP LOG READING
• The SSP is thequantity to be
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quantity to bedetermined.
• It is the deflectionseen on the SP fromthe Shale Base Line(zero point) to theSand Line (max.deflection)
SP USESP USES
• Differentiate potentially porous andpermeable reservoir rocks from
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pimpermeable clays.
• Define bed boundaries, top &bottom of the layer.
• For geological correlation
• Give an indication of shaliness(maximum deflection is clean;minimum is shale).
• Indicate vertical grain size
distribution• Determine Rw (formation water
resistivity) in both salt and freshmuds.
we
mfe
R
Rk SSP log−=
SP scale- + SP DEFLECTIONSP DEFLECTIONS
CORRESPOND TOORRESPOND TO
Rmfmf & Rww VALUESALUES
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S H A L E
B A S E
L I N
E
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SP BoreholeP Borehole
Effectsffects
• Baseline shifts: These can occur when there are beds
of different salinities separated by a shale which does
not act as a perfect membrane.
SP Surface EffectsP Surface Effects• The SP can be affected by a number of surface effects as it relies on
the fish as its reference electrode.
• Power lines, electric trains, electric welding, close radiotransmitters:
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• All these create ground currents which disrupt he "fish“ reference
causing a poor, sometimes useless, log.
GRR Principlesrinciples
• The Gamma Ray log is ameasurement of the formation'snatural radioactivity.
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• Gamma ray emission is produced by
three radioactive series found in theEarth's crust. – Potassium (K40) series. – Uranium series.
– Thorium series.• Gamma rays passing through rocks
are slowed and absorbed at a ratewhich depends on the formation
density.• Less dense formations exhibit moreradioactivity than dense formationseven though there may be the samequantities of radioactive material perunit volume.
GR USESR USES• Bed definition top,
bottom, thickness• Shalliness content
and net thickness, The
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and net thickness, Theminimum value gives
the clean (100%) shalefree zone, the maximum100% shale zone.
NEUTRON TOOLSNEUTRON TOOLS
• The first neutron tools used a chemical neutron source and
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The first neutron tools used a chemical neutron source andemployed a single detector which measured the Gamma Rays
of capture. They were non-directional. The units ofmeasurement were API units where 1000 API units werecalibrated to read 19% in a water-filled limestone. The tool wasbadly affected by the borehole environment.
• The second generation tool was the Sidewall Neutron Porosity(SNP). This was an epithermal device mounted on a pad.
• The current tool is the Compensated Neutron Tool (CNT). Thelatest tool is the Accelerator Porosity Sonde (APS), using anelectronic source for the neutrons and measuring in theepithermal region.
NEUTRONNEUTRON USESUSES
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• POROSITY &LITHOLOGYwith density log
• HYROCARBON
INDICATION
The tool measureshydrogen index
DENSITYENSITY• The Density Tools use a chemical gamma ray source
and two or three gamma ray detectors.
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g y
• The number of gamma rays returning to the detectordepends on the number of electrons present, the
electron density, ρe.
• The electron density can be related
to the bulk density of the minerals
by a simple equation.
• ρe = ρ( 2Z/A )
Where Z is the number ofelectrons per atom and A is
the atomic weight.
DENSITYENSITY Usesses
• The density tool is extremelyuseful as it has high accuracy
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g yand exhibits small borehole
effects.• Major uses include: – Porosity. – Lithology (in combination
with the neutron tool).• Mechanical properties (in
combination with the sonictool).
• Acoustic properties (in
combination with the sonictool).• Gas identification (in
combination with the neutrontool).
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SONICONIC OOLOOL The sonic tools create anacoustic signal and measurehow long it takes to pass
through a rock. By simply measuring this time
we get an indication of the
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we get an indication of theformation properties.
The amplitude of the signalwill also give informationabout the formation.
SONICONIC -BHCHC
• A simple tool that uses a pair of transmitters and four receiversto compensate for caves and sonde tilt.
• The normal spacing between the transmitters and receivers is3' 5'
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3' - 5'.
• It produces a compressional slowness by measuring the firstarrival transit times.
• Used for:
– Correlation.
– Porosity.
– Lithology.
– Seismic tie in /
time-to-depthconversion.
ARRAY SONICRRAY SONIC
• Multi-spacing digital tool.• First to use STC processing.
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• Able to measure shear waves
and Stoneley waves in hard
formations.
• Used for:
– Porosity.
– Lithology.
– Seismic tie in /
time-to-depth conversion. – Mechanical properties (from shear and compressional).
– Fracture identification (from shear and Stoneley).
– Permeability (from Stoneley).
Porosity 1orosity 1
• It reacts to primary porosity only, i.e. it does not "see“ the
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p y p y y,
fractures or vugs.• The basic equation for sonic porosity is the Wyllie Time
Average:
( ) ma f t t t Δφ1log
ma f
ma
t t
t t
Δ
Δ=
logφ
Porosity 2orosity 2
• Raymer Gardner Hunt.
• This formula tries to take into account some irregularities
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• This formula tries to take into account some irregularities
seen in the field.• The basic equation is:
• A simplified version used on the Maxis is:
C is a constant, usually taken as 0.67.
( ) f ma c t t t Δ
+Δ
−=
Δ
φ211
log
log
t
t tC
ma
Δ
Δ=
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DETECTINGETECTING
OVERPRESSUREDVERPRESSURED
ZONE WITH THEONE WITH THESONIC LOGONIC LOG
OVERPRESSURED ZONE
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LithologyLithology & Porosity& PorosityDeterminationDetermination
© Schlumberger 1999
Lithology Toolsithology Tools
• Most tools react to lithology - usually in conjunctionwith the porosity
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with the porosity.
• Major lithology tools are:
– Neutron - reacts to fluid and matrix.
– Density - reacts to matrix and fluid.
– Sonic - reacts to a mixture of matrix and fluid, complicatedby seeing only primary porosity.
– NGT - identifies shale types and special minerals.
– Geochemical logging, identifies 10 elements; K, U, Th, Al, Si,Ca, S, Fe, Gd, Ti
– From these the exact mineralogy can be computed.
Crossplot Solution
Porosity and
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• The plot is a straight line from the matrix point to the 100% porosity,
water point. It is scaled in porosity.
LithologyDetermination
from
Litho-Density* Logand CNL*
(Compensated NeutronLog)
Schlumberger Chart
2.48
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12
Porosity 13 %
75% sand & 25% limestone
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ELECTRICALELECTRICAL
RESISTIVITY LOGSRESISTIVITY LOGS
Resistivity Theoryesistivity Theory• The resistivity of a substance is a measure of its ability
to impede the flow of electrical current.• Resistivity is the key to hydrocarbon saturation
determination.
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Current can only passthrough the water in theformation, hence theresistivity depends on:
– Resistivity of theformation water.
– Amount of water present.
– Pore structure.
determination.
• Porosity gives the volume of fluids but does notindicate which fluid is occupying that pore space.
Resistivityesistivity Modelodel
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Smov = Sxo - Sw
NORMAL ToolsORMAL Tools• The voltage measured at M is proportional to the
formation resistivity.• This electrode configuration is the Normal tool.
• The distance between the A and M electrodes.
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• The spacing determines the depth of investigationand hence the resistivity being read.
NORMAL and LATERAL ToolsORMAL and LATERAL Tools
• The Lateral device usedthe same principle.
• The difference is in
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• The difference is inelectrode configurationand spacing.
• Problems came from "thinbeds" when the signatureof the curve was used to
try and find the trueresistivity.
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• This figure shows some of the "signature curves" for theinterpretation of lateral and normal devices in thin beds.
• A library exists plus the rules to extrapolate the measured value to
the true resistivity of the bed.
Laterolog Applicationsaterolog Applications
• Measures Rt.• Standard resistivity in high resistivity
environments.
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• Usable in medium-to-high salinity muds.
• Good results in high contrast Rt/Rm.
• Fair vertical resolution (same as porosity tools).
LATEROLOG LIMITS :
•Cannot be used in oil-based muds.•Cannot be used in air-filled holes.•Poor when Rxo > Rt.
MSFL PrincipleSFL Principle
• Uses: – Rxo measurement in
water-based muds.
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• This tool uses a set of 5 electrodeswhich focus the signal into the
invaded zone just beyond the mud
cake.
– Correction for deepresistivity tools.
– Sxo determination.
• Limits:
– Rugose hole.
– Oil-based mud. – Heavy or thick mud
cake.
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INDUCTION LOGSINDUCTION LOGS
© Schlumberger 1999
Induction LogsInduction Logs
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Induction Principle
UsesIL Uses and LimitsL Uses and Limits
• Measures Rt saturation
• Hydrocarbon content
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• Ideal in fresh or oil-basedenvironments.
• Ideal for low resistivity
measurements and when Rxo >Rt.
indications & fluid contacts• Bed definition, lithology,
shalliness
• Correlation• Abnormal pressure
examples 3
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• The AIT logs (2' vertical resolution) read correctly in this zone giving a hydrocarbon profile.• The DIL logs are ambiguous as the SFL (electrical log) longer reading shallow because Rxo
is less than Rt
90 Inch investigation(ohmm) 2000.2
0.2
0.2
0.2 2000.0
2000.0
2000.0
0.010000.0
(ohmm)
Cable tension (TENS)(LBF)
(ohmm)
SFL unaveraged (SFLU)
Medium resistivity (ILM)
(ohmm)Deep resistivity (ILD)
10 Inch investigation
(ohmm) 2000.2
20 Inch investigation(ohmm) 2000.2
30 Inch investigation
(ohmm) 2000.2
60 Inch investigation
(ohmm) 2000.2
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Saturationaturation• The saturation of a formation represents the amount of a given
fluid present in the pore space.• The porosity logs react to the pore space.
• The resistivity logs react to the fluids in the pore space.
• The combination of the two measurements gives the saturation
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g
Matrix
water
oil
Sw = S w irr + Sw "free"
So = S oresidual + So"free"
Resistivity Theoryesistivity Theory• Current can only pass through the water in the
formation, hence the resistivity depends on:
– Resistivity of the formation water.
– Amount of water present.
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– Pore structure.
Basics 1asics 1
• F: Formation Resistivity Factor.
F =
R 0
R w
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• At constant porosity F is constant.• As porosity increases, Ro decreases and F decreases.
• Experiments have shown that F is inversely proportional to φm
.
• m: is called the "cementation exponent".
• a: is called the "lithology" constant.
F =a
φ m
Basics 2asics 2
• Saturation can be expressed as a ratio of theresistivities:
Sw
n =R 0
R t
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where n is the "saturation exponent", an empirical constant.
Substituting for Ro:
Substituting for F:
S wn = FR w
R t
w
n
S =a
φ m
R w
R t
Saturation Equationaturation Equation
w
n
S =a
φ m
R w
R
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• The Archie equation is hence very simple. It links porosity andresistivity with the amount of water present, Sw.
• Increasing porosity, φ, will reduce the saturation for the sameRt.
• Increasing Rt for the same porosity will have the same effect.
φt
Invaded Zonenvaded Zone
• The same method can be applied to the invaded zone.The porosity is identical, the lithology is assumed to be
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the same, hence the constants a, n, m are the same.
• The changes are the resistivities which are now Rxo andRmf.
• Rmf is measured usually on surface and Rxo ismeasured by the MSFL tool.
• The equation is then: S xon = aR mf
φ m R xo
Ratio Methodatio Method
• Dividing for Sxo and Sw, with n set to 2
S w
S xo
=R xo R t
R mf R w
⎛
⎝ ⎜ ⎞
⎠⎟
1
2
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• Observations suggest:
• Hence:
S xo ≈ S w
1
5
S w =R xo R t
R mf R w
⎛ ⎝ ⎜
⎞ ⎠⎟
5
8
Archie parametersrchie parameters
• Rw = resistivity of connate water.
• m = "cementation factor", set to 2 in the simple case.
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• n = "saturation exponent", set to 2 in the simple case.• a = constant, set to 1 in the simple case.
All the constants have to be set.
In clastics the values are usually measured for each reservoir.
Values could be
m = 1.8 n = 2, a = 1
An often quoted old formula, the Humble Equation uses:
m = 2.15, n = 2, a = 0.62
Rw determinationw determination
• Rw is an important parameter.
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• Sources include: – Formation water analysis
– Local tables / knowledge.
– SP.
– Resistivity plus porosity in water zone.
– RFT sample.
– From Rxo and Rt tools.
Rw from Rwaw from Rwa• If Sw = 1, the saturation equation can become:
R w = φ 2R t
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• Assuming simple values for a, m, n.
• Procedure is to:• Compute an Rwa (Rw apparent) using this
relationship.
• Read the lowest value over a porous zone which
• This is the method employed by all computer basedinterpretation systems.
Rw from resistivityw from resistivity
• In a water zone Sw = 1, thus the alternativesaturation equation becomes:
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• The value of Rmf is measured;
• Rxo and Rt are measured, the value of Rw can becalculated.
Example of variations in the Archie parameters
Effects of parametersffects of parameters
w
n
S =a
φ m
R w
R t
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The following are measurements
POR = 25%, Rt = 5 ohm-m, Rw = .02 ohm-m
Assuming a simple formation witha = 1, m = 2, n = 2
Sw = 25%
Changing n to 2.5, changes the Sw to 33%
Changing m to 3 changes Sw to 50%
Hence the choice of these constants is important
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Shaly Sand Evaluationhaly Sand Evaluation
© Schlumberger 1999
Shaleshales
Clean formation Structural shale
PorosityMatrix Shale
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Porosity
Matrix
Porosity
Matrix
Porosity Shale
Matrix
Porosity
Matrix
Laminar shale Dispersed shale
S h a l e
S h a l e
Shale and Logshale and Logs• Shales have properties that have
important influences on log
readings:
• They have porosity.
• The porosity is filled with salted
water
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water.• They are often radioactive.
• Resistivity logs exhibit shales aslow resistivity zones.
• Neutron porosity logs exhibitshales as high porosity.
• Density and sonic logs react tothe porosity and matrix changes.
• Gamma ray logs react to shaleradioactivity.
Shale Volumehale Volume• The volume of shale must be computed to
correct the tool readings.• This is achieved using simple equations
such as:
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minmax
minlog
GRGR
GRGRV cl
−
−=
minmax
minlog
SPSP
SPSPV cl
−
−=
Shale Volumehale Volume
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Shale and Saturationhale and Saturation
• The Archie equation has to be changed totake account of the shale effect.
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• The shale looks like low resistivity soanother term is added to the equations.
• The result is an equation which will can beused to compute water saturation in shaly
sands.• All these equations return to Archies
equation if there is no shale present.
Saturation Equationsaturation Equations
•Indonesia Equation
S w =1
V cl
1 −V cl
2
⎛
⎝ ⎜⎜
⎞
⎠⎟⎟
R cl
+φ e
R w
*1
R t
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•Nigeria Equation
•Waxman-Smits Equation
•Dual Water Equation
1
R t
=S w
2
F * R w
+BQ v S w
F *
C t =φ t
m S wt
n
a
C w +S wb
S wt
C wb − C w( )⎡
⎣⎢
⎤
⎦⎥
1
R t
=V cl
1 . 4
R cl
+φ e
m2
aR w
⎛
⎝ ⎜
⎞
⎠⎟
2
S w
n
EXAMPLE : PROCESSED LOG
OPEN HOLE LOG
PROCESSED LOG
POROSITY & SATURATIONCALCULATION RESULTS
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VOLUMEFLUID
ANALYSIS
SATURATION
DUAL WATER MODEL DEFINITIONSUAL WATER MODEL DEFINITIONS
hydrocarbon
far
water φwf
φhy effective
porosity
φetotal
porosity
= φwf+ φ hy
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bound
water
dryclay
clean
matrix
fluids
solids
unitvolume
Vcl
wet clayVdcl
φwb
p yφ t
Clean to Shalelean to Shale
φ t
Matrix Far WaterSAND
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φ t
φ t
φ t
Matrix
Matrix
Dry Colloid
Dry Colloid
Bound waterSHALE
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Well Test ObjectivesWell Test Objectives1. Identify and Obtain reservoir fluids; oil, gas
& water
2. Determine basic reservoir parametes;
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2. Determine basic reservoir parametes;productivity (PI), permeability(k), skin (S),initial Resv. Pressure (P*) & Resv. Temp.
3. Well potential & deliverability (gas well) : Itmay be mandatory to proof field
commerciality4. Boundary & irregular conditions Reservoir
(GOC, OWC & Reservoir Limit)
WELL TESTING METHODSWELL TESTING METHODS
• HOLE CONDITION:
– OPEN HOLE
– CASED HOLE
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C S O
• TOOLS RUN IN HOLE : – WIRELINE TESTING : RFT, MDT & DST (IT WAS)
– PRODUCTION TEST WITH COMPLETION STRING
IN PLACE : DST
Surface Test Equipment
WELL TESTING SCHEMATICat
Cased Hole
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Downhole TestEquipment & Tool
DST & TCP
Subsea SafetyEquipment
DOWNHOLE TESTING EQUIPMENT
Open-Hole Sampling EquipmentRDT & RCI are equivalent with RFT/MDT
Formation Test Tool (FTT) samplechambers hold 420cc to 3 gallons of
reservoir fluid depending on make andmodel.
Open hole samples aid production and
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Baker RCI®
Halliburton RDT®
p p pfacility designs and are sometimes used
for PVT studies.
1ST GENERATION
RFTREPEATED FORMATION TESTER
- unlimited pressure survey
- 1 to 2 fluid sampling
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2ND GENERATION
MDTMODULAR FORMATION DINAMIC
TESTER
- unlimited pressure survey
- many fluid sampling (unlimited?)
- able to identify fluid type
- able to replace(pump out)unrequired fluid sample
SCHLUMBERGER
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DOWNHOLE TESTING
EQUIPMENT
RFT / MDT
Mud pressure
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Reservoir pressure
Build-up pressure
Example RFT Record
Wireline pen Hole Testing FT/MDT/RDT/RCI/etc.
• To identify the reservoirpressure
• To identify the fluid content
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o de t y t e u d co te t
• To estimate the permeability
• To estimate the productifity
• To define the fluid contact (OWC,OGC and GWC if any)
Fluid Contact Determinationwith fluid gradient from RFT
W a t e r G
r a d i e
n t 0 . 4 3 3 h
O
i l G r a d i e n t 0
. 3 6
7 p s i / f
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oil
water
RFT depth
3 p s i / f t
pressure
d e p t h f t
OWC
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Performing Well Test ith DST
• Clean up (flow)• Shut-in
• Main flow (one period or
flow-after-flow, flowingtest with 4 to 5 different
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test with 4 to 5 differentchoke size)
• Main Build –up (shut-in)
Selective Layer Testing
17 1/2”
26” 20 ft @ 500’
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8 1/2” 7” @ 17690’
12 1/4”
9 5/8” @ 15500’
Layer B
Layer A
Example :
TEST STRING
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DST & TCP
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Well Productivity
AOFP = 344 MMscf/d
CGR = 24.5 STB/MMscf/d
IPR plot3500
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Tested gas and condensate rates can beincreased to 125 MMscf/D and 3100 BPD
2.5E+550000
1500
1.5E+5 3.5E+52.5E+5
Gas Rate, Mscf/d
P r e s s u r e , p s i
Testing Risk Factors
Layers communication due topoor cement bond
High pressure and temperatures(over 350°F)
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(over 350 F)
Pressure and fluid loss through
packers Annulus-tubing fluid
communication
Water coning or sanding Layers crossflow
THE ROLE of WELLSITE/DEVELOPMENT GEOLOGIST (DG) in WELL TESTING
OPEN HOLE TESTINGwith RFT/MDT
CASED HOLE TESTINGwith DST
DG Propose/selects the testing/perforation sand, interval and depth
Estimate the reservoir fluid contents and it’s static pressure
Provide the reservoir rock parameter for testing analysis such as lithology porosity
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Provide the reservoir rock parameter for testing analysis such as lithology, porosityand permeability if any (from log, or qualitative)
Stop the testing when unsafe operation Testing Engineer (TE) decision
Decide testing duration TE decide flow & shut-in periods. TE alsoselects choke size for flow testing.
Select taken fluid sample TE decide fluid sampling methods. Andresponsible for fluid sample handling
As Operation Witness will validate &analyse the result
TE is prime Operation Witness and willvalidate & analyse the testing result.
DG & TE will be along selecting theperforation method
PERFORATION1. THROUGH CASING GUN
Hyperjet/HSD(high shot density)
2. THROUGH TUBING GUN Enerjet
3. TCP (Tubing Conveyed Perforation)
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GUN TYPES
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DG and/or Wellsite eologist Responsibilities n Perforation Job
1. Define the perforation intervals atporous zone & hydrocarbon zone(pay zone.
2. Evaluate and prepare the perforationdesign such as gun type, size, SPF( h t ft) S i ( l b t
PERF. At Net pay
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(shot per ft), Spacing (angle betweentwo shots), charge/explosive type;
penetration deep and entrance hole.3. Perforation environment (fluid type
in the hole); using mud or brinewater or special completion fluid,
under/over balance.4. Witness the gun loading, correlation,
shooting result (whether all chargesexploded or not) “SAFETY FIRST”
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THE RESERVOIRTHE RESERVOIR
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PETROLEUMPETROLEUMRESERVOIRRESERVOIR
• ROCK PROPERTIES
• FLUID PROPERTIES
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U O S
• PRESSURE
• RESERVOIR DRIVE
ROCK PROPERTIESROCK PROPERTIES
Rocks are described by three properties:
– Porosity - quantity of pore space
– Permeability - ability of a formation to flow
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– Matrix - major constituent of the rock
note: porosity & permeability has been discussed partially in
“Chapter I. Introduction”
• Permeability is a property of the porous medium and is a
measure of the capacity of the medium to transmit fluids
• Absolute Perm: When the medium is completelysaturated with one fluid, then the permeability
measurement is often referred to as specific or absolutepermeability
PERMEABILITY PERMEABILITY
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• Effective Perm: When the rock pore spaces contain
more than one fluid, then the permeability to a particularfluid is called the effective permeability. Effectivepermeability is a measure of the fluid conductancecapacity of a porous medium to a particular fluid when
the medium is saturated with more than one fluid• Relative Perm: Defined as the ratio of the effective
permeability to a fluid at a given saturation to theeffective permeability to that fluid at 100% saturation.
DARCY DARCY ’’S LAW S LAW
q
Direction of flow A
p2 p1L
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L = lengthq = flow rate
p1, p2 = pressures
A = area perpendicular to flow
μ
= viscosity
)( 21 p p L
Aq k
−•=
k = permeability(measured in darcies)
k/ μ =
kh/ =
DARCY DARCY ’’S LAW:S LAW: RADIAL FLOW RADIAL FLOW
. rrw
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h = height of the cylinder (zone)
P = pressure at r
Pw = pressure at the wellbore
rw / rln ) Pw P( khq
μ−= 2
PERMEABILITY PERMEABILITY –– POROSITY POROSITY
CROSSPLOTCROSSPLOT
100
10
10
100
1000
t y ( m d )
Limestone A1 Sandstone A1
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1
0.1
0.01 0.01
0.1
1
10
2 6 10 14 2 6 10 14 18
P e r m e a b i l i
Porosity (%)
• Oil
k
kk eo
ro =
k
CALCULATING RELATIVECALCULATING RELATIVE
PERMEABILITIESPERMEABILITIES
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• Water
• Gas
k
k
kew
rw =
kkk
egrg =
Relative Permeability Curveelative Permeability Curve
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IRREDUCIBLE WATER SATURATIONRREDUCIBLE WATER SATURATION• In a formation the minimum saturation induced by
displacement is where the wetting phase becomesdiscontinuous.
• In normal water-wet rocks, this is the irreducible water
saturation, Swirr.• Large grained rocks have a low irreducible water
saturation compared to small-grained formations
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saturation compared to small-grained formationsbecause the
capillary
pressure is
smaller.
TRANSITION ZONERANSITION ZONE• The phenomenon of capillary pressure gives rise to the
transition zone in a reservoir between the water zone and theoil zone.
• The rock can be thought of as a bundle of capillary tubes.
• The length of the zone depends on the pore size and the
density difference between the two fluids.
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Relativeelative
Permeabilityermeability
• Take a core 100% water-saturated. (A)
• Force oil into the coreuntil irreducible watersaturation is attained
(Swirr). (A-> C -> D)• Reverse the process:
force water into the core
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force water into the coreuntil the residualsaturation is attained. (B)
• During the process,measure the relativepermeabilities to waterand oil.
FLUID SATURATIONSLUID SATURATIONS• Basic concepts of hydrocarbon accumulation
– Initially, pore space filled 100% with water
– Hydrocarbons migrate up dip into traps – Hydrocarbons distributed by capillary forces and gravity – Connate water saturation remains in hydrocarbon zone
• Fluid saturation is defined as the fraction of pore volumeoccupied by a given fluid
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• Definitions
Sw = water saturationSo = oil saturationSg = gas saturationSh = hydrocarbon saturation = So + Sg
• Saturations are expressed as percentages or fractions, e.g. – Water saturation of 75% in a reservoir with porosity of 20%
contains water equivalent to 15% of its volume.
SATURATIONATURATION
• Amount of water per unit volume = φ
Sw
• Amount of hydrocarbon per unit volume = φ
(1 - Sw) =
φ
Sh
(1 S )
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φ
Matrix1 − φ
Water
Hydrocarbon (1-Sw)
φ Sw
RESERVOIR PRESSUREESERVOIR PRESSURE
• Lithostatic pressure is caused by thepressure of rock, transmitted by grain-to-grain contact.
• Fluid pressure is caused by weight ofl f fl id i h
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column of fluids in the pore spaces.Average = 0.465 psi/ft (saline water).
• Overburden pressure is the sum of thelithostatic and fluid pressures.
RESERVOIR PRESSUREESERVOIR PRESSURE• Reservoir Pressures are normally controlled by the
gradient in the aquifer.
• High pressures exist in some reservoirs.
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RESERVOIR TEMPERATURE GRADIENTESERVOIR TEMPERATURE GRADIENT
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The chart shows three possible temperature gradients. Thetemperature can be determined if the depth is known.
High temperatures exist in some places. Local knowledge is important.
FLUIDS IN A RESERVOIRLUIDS IN A RESERVOIR• A reservoir normally contains either water or
hydrocarbon or a mixture.• The hydrocarbon may be in the form of oil or
gas.
• The specific hydrocarbon produced dependsth i d t t
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on the reservoir pressure and temperature.
• The formation water may be fresh or salty.
• The amount and type of fluid produceddepends on the initial reservoir pressure,rock properties and the drive mechanism.
HYDROCARBON COMPOSITIONYDROCARBON COMPOSITION
• Typical hydrocarbons have the following composition in Mol Fraction
• Hydrocarbon C1 C2 C3 C4 C5 C6+
• Dry gas .88 .045 .045 .01 .01 .01
• Condensate .72 .08 .04 .04 .04 .08
• Volatile oil 6- 65 08 05 04 03 15- 2
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• Volatile oil .6-.65 .08 .05 .04 .03 .15-.2
• Black oil .41 .03 .05 .05 .04 .42
• Heavy oil .11 .03 .01 .01 .04 .8
• Tar/bitumen 1.0
• The 'C' numbers indicated the number of carbon atoms in the molecular chain.
HYDROCARBON STRUCTUREYDROCARBON STRUCTURE
• The majorconstituent ofhydrocarbons is
paraffin.
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HYDROCARBON CLASSIFICATIONYDROCARBON CLASSIFICATION
• Hydrocarbons are also defined by their weight and the Gas/Oil ratio. Thetable gives some typical values:
GOR API Gravity
• Wet gas 100mcf/b 50-70
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• Condensate 5-100mcf/b 50-70
• Volatile oil 3000cf/b 40-50
• Black oil 100-2500cf/b 30-40
• Heavy oil 0 10-30
• Tar/bitumen 0 <10
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FLUID PHASESLUID PHASES
• A fluid phase is a physically distinct state, e.g.: gas oroil.
• In a reservoir oil and gas exist together at equilibrium,
depending on the pressure and temperature.
• The behaviour of a reservoir fluid is analyzed using the
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y g
properties; Pressure, Temperature and Volume (PVT).• There are two simple ways of showing this:
– Pressure against temperature keeping the volume constant.
– Pressure against volume keeping the temperature constant.
PVT ExperimentVT Experiment
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PHASE DIAGRAM SINGLE COMPONENTHASE DIAGRAM SINGLE COMPONENT• The experiment is conducted at different temperatures.
• The final plot of Pressure against Temperature is made.
• The Vapour Pressure Curve represents the Bubble Pointand Dew Point.
• (For a single component they coincide.)
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THE FIVE
RESERVOIR
FLUIDS
Black Oil
Criticalpoint
P r e s s u r e , p s i a
B u b b
l e p o i n
t l i n e
Separator
Pressure pathin reservoir
Dewpoint line
9 0
8 0
9 0
7 0
6 0
5 0
4 0
1 0
3
0
2 0
% Liquid
Temperature, °F
P r e s s u r e
Temperature
Separator
% Liquid
B u b b l
e p o i n t
l i n e
D e w p o i n
t l i n e
Dewpoint line
Volatile oil
Pressure pathin reservoir
3
2
1
5
1 0
3
3 0
2 0
4 0 5 0
6 0
7 0
8 0
9 0
Criticalpoint
Black Oil Volatile Oil
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3
3 0 2 0
1 5
1 0
4 0
Separator
% Liquid
Pressure pathin reservoir
1
2Retrograde gas
Criticalpoint
B u b b
l e p o
i n t l i n
e
D e w
p o i n t l i n
e
5
0
P r e s s u r e
Temperature
P r e s s u r e
Temperature
% Liquid
2
1
Pressure path
in reservoir
Wet gas
Critical
point
B u b b l e p o i n
t
l i n e
Separator
1 5 2 5 3 0
D e w p o i n
t l i n
e
P r e s s u r e
Temperature
% Liquid
2
1
Pressure path
in reservoir
Dry gas
Separator 2 5
D e w p o i n
t l i n
e
1 5 0
Retrograde Gas Wet Gas Dry Gas
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FIELD IDENTIFICATION
BlackOil
VolatileOil
RetrogradeGas
WetGas
DryGas
Initial
ProducingGas/LiquidRatio, scf/STB
<1750 1750 to
3200
> 3200 > 15,000* 100,000*
Initial Stock- < 45 > 40 > 40 Up to 70 No
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Tank LiquidGravity, °API
p
Liquid
Color of Stock-Tank Liquid
Dark Colored LightlyColored
WaterWhite
NoLiquid
*For Engineering Purposes
LABORATORY ANALYSIS
BlackOil
VolatileOil
RetrogradeGas
WetGas
DryGas
PhaseChange inReservoir
Bubblepoint Bubblepoint Dewpoint NoPhase
Change
NoPhase
ChangeHeptanesPlus, MolePercent
> 20% 20 to 12.5 < 12.5 < 4* < 0.8*
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Percent
OilFormationVolumeFactor at
Bubblepoint
< 2.0 > 2.0 - - -
*For Engineering Purposes
PRIMARY PRODUCTION TRENDS
G O R
G O R
G O R
G O R
G O R
Time Time TimeTimeTime
Noliquid
DryGas
WetGas
RetrogradeGas
VolatileOil
BlackOil
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TimeTimeTimeTimeTime
No
liquid° A P I
° A P I
° A P I
° A P I
° A P I
BLACK OIL FLUID PROPERTIES
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Sample : DRY GAS FLUID PROPERTIS
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FVF ormationVolume Factor
• Fluids at bottom holeconditions producedifferent fluids atsurface:
• Oil becomes oil plusgas.
• Gas usually stays as
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gas unless it is aCondensate.
• Water stays as waterwith occasionally
some dissolved gas.
FLUID VISCOSITY
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Water Invasion• Water invading an oil zone, moves
close to the grain surface, pushingthe oil out of its way in a piston-
like fashion.
• The capillary pressure gradientforces water to move ahead fasterin the smaller pore channels.
• The remaining thread of
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oil becomes smaller.• It finally breaks into smaller
pieces.
• As a result, some dropsof oil are left behind in
the channel.
Water DriveOil producing well
Oil Zone
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• Water moves up to fill the "space"
vacated by the oil as it is produced.
Water Water
Cross Section
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Water Drive 2
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• This type of drive usually keeps the reservoir pressure fairlyconstant.
• After the initial “dry” oil production, water may be produced. Theamount of produced water increases as the volume of oil in thereservoir decreases.
• Dissolved gas in the oil is released to form produced gas.
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Gas Cap Drive
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Gas from the gas cap expands to fill the spacevacated by the produced oil.
Gas Cap Drive 2
• As oil production declines, gas production increases.
• Rapid pressure drop at the start of production.
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Solution Gas Drive 2
• An initial high oil production is followed by a rapid decline.
• The Gas/Oil ratio has a peak corresponding to the higherpermeability to gas.
• The reservoir pressure exhibits a fast decline.
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GRAVITY DRAINAGE
Oil
Oil
Point C
Gas
Gas
Gas
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Oil
Point A
Point B
Recovery = to 60% of OOIP
Drives General
• A water drive can recover up to 60% of the oil in place.• A gas cap drive can recover only 40% with a greater
reduction in pressure.
• A solution gas drive has a low recovery.
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5
4
3
2 i l r a
t i o ,
M S C
F / S
T B
Gas-cap drive
Solution-
gas drive
Gas/oil Ratio Trends
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1
0
Cumulative oil produced, percent of original oil in place
0 20 40 60 80 100
G a s / o
Water drive
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Drive ProblemsWater Drive:• Water can cone upwards and be
produced through the lowerperforations.
Gas Cap Drive:• Gas can cone downwards and be
produced through the upperperforations.
Pressure is rapidly lost as the gas
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• Pressure is rapidly lost as the gasexpands.
Gas Solution Drive:• Gas production can occur in the
reservoir, skin damage.
• Very short-lived.
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Secondary Recovery • Secondary recovery covers a range of techniques used to
augment the natural drive of a reservoir or boost production ata later stage in the life of a reservoir.
• A field often needs enhanced oil recovery (EOR) techniques tomaximise its production.
• Common recovery methods are: – Water injection.
– Gas injection.
I diffi lt i h th t i i h il
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• In difficult reservoirs, such as those containing heavy oil, moreadvanced recovery methods are used:
– Steam flood.
– Polymer injection. . – CO2 injection.
– In-situ combustion.
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• To demonstrate reservoirproperties in a plan view
projection with objectives topromote optimal fielddevelopment.
• The maps will be used forwell placement, reservescalculation, reservoirperformance monitoring.
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• Mapping is part of reservoircharacterization, thereforethe results of which very
depend on the expert’sworking knowledge inapplied geologic models
WELL PLACEMENT
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• TOP/SURFACE MAPS : – Structure Map
– Fault Map
– Unconformity Map
• THICKNESS MAPS : – Isopachous Map Gross & Net
• OTHERS & COMBINED MAPS :
Carried out by DG
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• OTHERS & COMBINED MAPS : – Isoporosity Map - Isopermeability Map
– Pressure Map - Saturation Map
– Productivity Map - Shale Map
– Net to Gross Sand Map - Etc.
MAPPINGMAPPING
CONCEPTUAL WORKFLOWCONCEPTUAL WORKFLOW
1. GEOLOGIC MODEL1. FACIES2. STRATIFICATION3. CONTINUITY
4. TRENDS5. TECTONIC
2. GEOLOGICAL MAP1. STRUCTURE2. ISOPACH
3. FAULTS/BARIER
SEISMIC
WELL LOGS
CORE & CUTTING
ANALYSIS
INTERPRETATION,ZONATION,
INTEGRATION,CORRELATION,
ANALYSIS&
D A T A PROCESING
PROCESSING PRODUCTS
REGIONALGEOLOGY
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4. UNCONFORMITY
3. RESERVOIR MAP1. NET PAY
2. POROSITY3. PERMEABILITY4. PRESSURE5. PRODUCTIVITY
S S
WELL TESTS &PRESSURE
FLUID ANALYSIS
PRODUCTIONDATA
S S&
DEFINE VALUES
BASIC KNOWLEDGEBASIC KNOWLEDGE
FOR RESERVOIR CORRELATION & MAPPINGFOR RESERVOIR CORRELATION & MAPPING
• LOG ANALYSIS (electro-facies, reservoir parameters,stratigraphy, structure, etc.)
• SEISMIC INTERPRETATION (structure, reservoircontinuity, hydrocarbon indications)
• SEDIMENTARY FACIES, DEPOSITIONALENVIRONMENTS & SEQUENCE STRATIGRAPHY
• MODELS OF BASINS & RESERVOIRS, AND ALSOREGIONAL GEOLOGY OF THE MAPPED FIELDtrends of sedimentation & major tectonic and it’sramifications
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trends of sedimentation & major tectonic and it sramifications
• BASIC RESERVOIR ENGINEERING pressure regime,models, fluid propertie and production performance.
• BASIC COORDINATE SYSTEMS/GEOMETRY &STEREOMETRY base map, well trajectory, leaseboundary etc.
LOG ANALYSISFOR RESERVOIR CORRELATION & MAPPING
• LITHOLOGY / FACIES IDENTIFICATIONS &MARKERS DETERMINATION continuity, consistency,missing sections & repetition sections (faults or overturn)
• DEPOSITIONAL ENVIRONMENT
• VERTICAL ZONATIONS
– TOP & BOTTOM
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– FLOW UNIT
• FLUID CONTACTS OWC, GOC & GWC
• RESERVOIR PARAMETERS Por, Perm, Sw etc
• NET PAY THICKNESS DETERMINATIONS
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FMI fulbore formation micro imagerRAB resistivity at the bit
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SEISMIC FOR RESERVOIR GEOLOGY
• Aid in : – Reservoir facies mapping reservoir distribution : lithology,
isopach etc 3D – Reservoir properties mapping porosity – Locating / define fluid contacts
– Monitoring fluid fronts 4D – Sructure & stratigraphic interpretations
• Seismic methods : – 2D Seismic
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– 3D seismic – VSP – Well to well seismic – Time-lapse seismic monitoring etc.
EXPLOSIVE
LAPISAN BATUAN
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LAPISAN BATUAN
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VSPV S P(Vertical Seismic Profiling)
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SLB, OFR, 2007 Autumn
Example :
Comparison of VSP & Seismic Results
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SLB, OFR, 2007 Autumn
SURFACE SEISMIC IMAGESURFACE SEISMIC IMAGE
TIES WITH VSP
3D Seismic
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Basic of 4D Seismic
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Example : 4D Seismic uses
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DEPOSITIONAL ENVIRONMENTSDEPOSITIONAL ENVIRONMENTS
AND SEDIMENTARY FACIESAND SEDIMENTARY FACIES
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Distinctive and Common SedimentaryDistinctive and Common Sedimentary
Facies AssociationsFacies Associations
Vertical successionsprincipally identifiedby lithology,associations and
vertical arrangementof sedimentarystructures indicative ofparticularsedimentarydepositional
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depositionalenvironments
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CARBONATE DEPOSITIONAL ENVIRONMENTS
(DIAGRAM BY R.G. LOUCKS AND C.R. HANDFORD, UNPUBLISHED)
SEQUENCE STRATIGRAPHY CONCEPTSSEQUENCE STRATIGRAPHY CONCEPTS• Sequence stratigraphy highlights the role of allogenic controls on
patterns of deposition, as opposed to autogenic controls thatoperate w ithin depositional environments
– Eustasy (sea level)
– Subsidence (basin tectonics)
– Sediment supply (climate and hinterland tectonics)
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COMPONENTS OF SEQUENCES
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SLB, OFR, JAN93
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GROSS NET NET PAY
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LEVELS OFRESERVOIRHETEROGENETY
(fluviatil rock)
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Schematic Reservoir Layering Profile
in a Carbonate ReservoirBaffles/barriers
3150
SA -97A SA -251 SA -356 SA -71 SA -344 SA -371 SA -348 SA -346 SA -37
3200
3250
3300
3100
3150
3250
3300
3250
3150
3200
3100
3150
3200
3200
3250
3250
3150
3200
3250
3100
3200
3150
3200
3250
Flow unit
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33503250
3350
3300
3300
3250
3300
3350
From Bastian and others
E
• BASED ON :
– PRODUCTION TESTINGS the most
reliable methods
– LOGS (electrical logs combined with FDC &
CNL)
PRESSURE SURVEY pressure gradient
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– PRESSURE SURVEY pressure gradient
from RFT – SEISMIC hydrocarbon indications
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CORRELATIONSCORRELATIONS
• “Reservoir Correlation” is part of pre-mapping worksof reservoir to locate and trace the lateraldistribution, continuity, geometry of reservoirs and
it’s flow unit.
• Correlation should be carried out based all theavailable data, a sedimentological and stratigraphic
model of the reservoirs.• Some pre-correlation works notes:
– Wireline log will be the basic data and will be calibrated andintegrated with other data analysis results such as core
analysis especially. – Vertical profile analysis of well data should be carried out
previously to establish the facies, sequences and
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p y , qsedimentary environment.
– Zonation of lithology and flow unit, and also markerinentifications should be geologically sound. – Define the zone top & bottom, zone thickness (gross & net)
etc.
Tips for Correlation
• Stratigraphic Cross Section is the best demonstration of acorrelation results.
• The section should show reservoir lateral and vertical facieschanges, markers continuity, missing & repetition sections,completion & prod. testing notes, etc.
• Good markers can be organic shale, coal/lignite, limestone beds,
glauconite, siderite etc. which has good continuity andcorrespond to the geologic events such as maximum flooding,emmergence etc.
• Start the correlation with the whole log section of individual well,make zonation based on electro facies then define all markersand zones of interest. Indicates any missing and repetitionsection. Then carry out a detail correlation of objective reservoirs.
• For reservoir connectivity indication use also fluid contents and
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• For reservoir connectivity indication use also fluid contents andcontacts, pressure data and production performance data
• Prepare a good tabulation (database) of geologic data such asdepth of top & bottom of reservoir, net & gross thickness, fault’sdepth etc.
CORRELATION
PROBABILISTIC to DETERMINISTIC
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After EA Arief S, IPA, 2001
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B
C
D
LATIHAN
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A
LATIHAN
OIL
OIL OWCA
C
B
D
WELL #123
WELL #456
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C
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LATIHAN
OIL
OIL OWCA
C
B
D
WELL #123
WELL #456
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C
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Tip for Reservoir Mapping
• Prepare a good base-map based on coordinates ofwells and seismic shot points (line & BM).
• Plot the data accurately then start contouring fromthe highest positions for structure and refer toseismic maps.
• Stucture contour should be stop whenevercross/meet the fault plane. Consider the faultthrows and missing/repetition sections for the next
blocks contouring.• For isopach maps initiate with facies map
construction then followed with isopach contouring
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construction then followed with isopach contouring.
• Understand the contouring principles such as nocrossing contour etc.
-
1 0 0 0 ’
- 1 1
0 0 ’
- 1 2 0 0
’ - 1 3 0 0 ’
- 1 2 0 0 ’
- 1 1 0 0 ’
- 1 0 0 0 ’
- 1 0 0
0 ’
- 1 1
0 0 ’
- 1 2 0 0 ’
- 1 1 0
0 ’
- 1 0 0 0
’
- 1 2 0 0 ’
- 1 2 0 0 ’
- 1 0 0 0
’
- 1 1 0
0 ’
- 1 2 0
0 ’
- 1 1 0
0 ’
- 1 0 0 0
’
1 0 ’
2 0 ’
2 0 ’ 1 0
’ 0 ’
2 0 ’
1 0 ’
0 ’
2 0 ’
3 0 ’
3 0 ’
2 0 ’
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0 ’ 0 ’
1 0 ’
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-1 0 0 0 ’
-11 0 0 ’
-1 2 0 0 ’
-1 3 0 0 ’
-1 4 0 0 ’
-1500 ’
-1600’
-1700’
-1600 ’
-1 5 0 0 ’
- 1 4 0 0 ’
- 1 3 0 0 ’
PLAN VIEW
SECTION VIEW
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-1 700’
- 1 7 0 0 ’
- 1 6 0 0 ’
- 1 5 0 0 ’
- 1 4 0 0 ’
- 1 3 0 0 ’
- 1 2 0 0 ’
- 1 1 0 0 ’
- 1 0 0 0 ’
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100010 10
102010 3 0
1040
NET PAY MAP CONSTRUCTION
STRUCTURE MAP
C
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1050
Contour unit in meter sub-sea
Contour interval 10 mOWC @ 1050
mss
0
5 m
1 0 m
1 5 m
NET PAY MAP CONSTRUCTION
ISOPACHOUS MAP
C t it i t15 m
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1 0 m
5 m
0 m
Contour unit in meter
Contour interval 5 m
0 m
5 m
1 0 m
1 5 m
NET PAY MAP CONSTRUCTION
NET PAY MAP
1 51 0
5 C t it i t
10 10
1020
10 3 0
1040
1050
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1 0 m
5 m
0 m
5 0
Contour unit in meter
Contour interval 5 m
d o w n
FAULT MAP
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SURFACES OF FAULTS X AND Y
WEST-EAST CROSS SECTION
A S a
n dA S a n d
B S
a n d
B S a n d
B
U N C O N F O R
M I T Y
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STRUCTURE MAP OF A SAND
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ISOPACHOUS MAP OF A SAND
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NET PAY MAP OF A SAND
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STRUCTURE MAP OF B SAND
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ISOPACHOUS MAP of B SAND
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NET PAY MAP OF B SAND
NET GAS
NET OIL
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FAULT ANALYSISSEALING OR NON SEALING
• Can be based on : – Log analysis
– Well test data
– Pressure build-up analysis – Interference test
– Production data
– Using radioactive tracer
– Core & Rock Cutting
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– Correlation & Sratigraphic analysis
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ALLAN DIAGRAM
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Disagregated& cemented
Phillosillicate-smear
framework
clay-smearfault rocks
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A
B
A
B
C
C
D
D
E
E
F
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Allan Diagram for non-sealing fault
DOWN BLOCK
UP BLOCK
DOWN BLOCK
UP BLOCK
Common Oil Water Contacts
OIL
OILOIL
OIL
WATER
WATER
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0 m
5 m
1 0 m
1 5 m
1 0 m
NET PAY MAP CONSTRUCTION
NET PAY MAP
1 51 0
5 0
Contour unit in meter
10 10
1020
10 3 0
10401050
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5 m
0 m
Contour interval 5 m
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• The most important role of a DG is to:
– estimate the oil and gas reserves that may
be discovered in a particular venture.
– keep track of the reserves in all pastventures.
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THE 4 BASIC RESERVES ESTIMATION ETHODS
1. Educated Guess and/or Comparisonwith nearby production.
2. Static Reserves Estimates Volumetric Calculations
3. Dynamic Reserves Estimates Decline Curve Analysis
Material balance calculations
Reservoir Simulation
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THE EDUCATED GUESS and/orCOMPARISON OF NEARBY PRODUCTION
•Consider a region where production is from ahighly fractured tight formation or whereporoperm heterogeneity is unpredictable.
• Volumetric calculations are largelymeaningless.
• A way to estimate potential production from
a well is to consider those nearby.• Generally, such a wildcat well will not
perform better than the nearest wells: best to
ti t ti l
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estimate cautiously
VOLUMETRICS
• Most accurate and widely used methods of reservesestimation.
• Carried out by geologists as they are based ongeological structure and isopach maps.
• Rock volumes are established that are assumed to
contain hydrocarbons (e.g. seismic bright spot).• Can be a simple volume calculation or a complex net
gas or net oil isopach approach, determined by
structure contours modified by fluid contacts and netisopachs (net reservoir thickness map).
• Accuracy of volumetrics depends on data for porosity,saturation, net thickness, areal extent, formation
l f t i t g it f th d t ithi i
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volume factor, integrity of those data within a reservoir.
Volumetric Method• RR = 7758 x A.t x φ(1 – Sw) x FVF x RF
• Amount of oil in reservoir • Amount of recoverable oil
RR = Recoverable Reserves 7758 = conversion from acreft to barrels (if vol. in
m3. this conversion number is eliminated)
A = area of porous rock, acre
t = thickness in feet
φ = porosity,%
(1-Sw) = water saturation of reservoir
FVF Formation Volume Factor (1/Bo & 1/Bg)
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FVF = Formation Volume Factor (1/Bo & 1/Bg) Bo/Bg reservoir volume / surface volume (vr / vs )
RF = Recovery Factor
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HORIZON MAP(Superimposed Structure and Net Isopach Maps)
0 m
5 m
1 0 m
1 5 m
1 0 m
5 m
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5 m
0 m
NET PAY MAP
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Rock Volume Calculations2 methods :
1. PYRAMID
2. TRAPEZOIDS
A : area, m2 or acre
h : isopach/contour interval, m or ft
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h : isopach/contour interval, m or ftn : contour number (0 n)t : avg. thickness above the top of max. thickness
FVF
ormation Volume Factor
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RFRecovery Factor
• Usually RF determination is carried out by
Reservoir Engineer.
• Mainly based on the reservoir drive, rock
properties and fluid properties.
• For oil with effective water drive the
primary recoveries are in 25 – 40 % range(max. 75%).
• For gas with gravity drainage water drived d l i d i id RF 80%
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• For gas with gravity drainage, water driveand depletion drive can provide RF > 80%.
Average Oil RecoveryFactors,% of OOIP
Drive Mechanism
Range AverageSolution-gas drive 5 - 30 15Gas-cap drive 15 - 50 30Water drive 30 - 60 40
Gravity-drainagedrive
16 - 85 50
Average Gas RecoveryFactors,
% of OGIPDrive Mechanism
Range Average
Volumetric reservoir(G i d i )
70 - 90 80
Average Recovery Factors
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Volumetric reservoir(Gas expansion drive)
70 90 80
Water drive 35 - 65 50
SOURCESOF ATA
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Decline Curve Analysis
(Reservoir Engineer’s jobs)
• After wells have been producing for a while:
– The rate of production is graphed
– Generally 6 months – 1 year after start of
production• Good reserves estimates can be derived.
Often compared with volumetric techniqueresults.
• Can be done by well, by a group of well, by
block, by reservoir, by field
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block, by reservoir, by field
Decline Analysis Results• Determine remaining recoverable reserves
under natural depletion rate.
• To forecast production under existingconditions
• Limitation: – The degree of the accuracy is depend on the
reliability of the production data.
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reliability of the production data.
DECLINECURVE
EQUATIONS
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Production Plots
1. A plot of log(q) vs t is
Linear if decline is exponential Concave upward if decline is hyperbolic (n>0) or harmonic
2. A plot of q vs Np is Linear if decline is exponential
Concave upward if decline is hyperbolic(n>0) or harmonic
3. A plot of log(q) vs Np is Linear if decline is harmonic
Concave downward if decline is hyperbolic (n<1) or exponential Concave upward if decline is hyperbolic with n>1.
4. A plot of 1/q vs t is Linear if decline is harmonic
Concave downward if decline is hyperbolic (n<1) or exponential Concave upward if decline is hyperbolic with n>1.
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Concave upward if decline is hyperbolic with n>1.
Example. Exponential declinexample. Exponential decline
Example. Exponential decline
q = 6049.1e-0.0524 t
100
1000
10000
0 10 20 30 40 50 60time (quarter year)
R a t e , s t b / d
.
Slope=-D 1/quarter year
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time (quarter year)
Example. Exponential declinexample. Exponential decline
Example. Rate decline with production
q = -0.4301Np + 5768.7
0
1000
2000
3000
4000
5000
6000
7000
0 2000 4000 6000 8000 10000 12000 14000
Cum prod MSTB
q s t b / d
q abondonment
Reserves
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Cum. prod, MSTB
Example. Harmonic declinexample. Harmonic decline
0
2000
4000
6000
8000
10000
12000
0 2 4 6 8 10 12 14 16
Time (years)
R a t e ( s t b / d )
0
5
10
15
20
25
30
35
40
C u m .
P r o d u c t i o n ( M M s t b )
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Example. Hyperbolic declinexample. Hyperbolic decline
Hyperbolic Decline curve
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
0 50 100 150 200 250 300 350
q S T B /
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days
General Concept of Material Balance.
From: Petroleum Reservoir Engineering
— Amyx, Bass, and Whiting (1960).
a. Initial reservoir conditions. b. Conditions after producing N p
STB of oil,and G p SCF of gas, and W p STB of water.
Material Balance: Key Issues
Must have accurate production measurements (oil, water, gas). Estimates of average reservoir pressure (from pressure tests). Suites of PVT data (oil gas water)
MATERIAL BALANCEMATERIAL BALANCE
of a Petroleum Reservoir(Mostly carried out by Reservoir Engineer)
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Suites of PVT data (oil, gas, water).
Reservoir properties: saturations, formation compressibility, etc.
RESERVOIR SIMULATION (RS)RESERVOIR SIMULATION (RS)
• Reservoir Modelling: primarily the reservoirengineer’s job.
• RS applies the concepts and techniques of math-ematical modeling to the analysis of the behavior ofpetroleum reservoir systems.
• In a narrower sense refers only to the hydro-
dinamics of flow within reservoir.• In a larger sense refer to the total petroleum
system which includes the reservoir, the surface
facilities, and any interrelated significant activity, andeconomic
• The basic flow model the partial differentialequations using finite difference methods whichgovern the unsteady state flow of all fluid phases inh i di
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the reservoir medium.
RESERVOIRRESERVOIR
SIMULATORSIMULATOR
Rock data
Fluid data
Production data
Pressure data
Flow rate data
Mechanical &operational data
Miscellaneousdata
INPUTINPUT PROCESSEDPROCESSED
in the BLACK BOXin the BLACK BOXOUTPUTOUTPUT
Reserves
Reservoir modelPlan of reservoirdepletion
Productionforecast
Optimumproduction
RESERVOIR SIMULATIONESERVOIR SIMULATION
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Reservoir link with surface facility
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• Prepare the array input data (maps) of individual flow
unit : structure (top & bottom), isopach (net & gross),porosity, permeability, rock compressibility etc.
• Advising to simulation engineer in the designing of
the grid model and layer divisions.• Trace and established in the model grid the
existence of faults, horizontal and vertical barriers
permeability.• During the history matching of production, pressure
etc., DG advises to simulation engineer in allowable
geological modification such as thickness, structure,rock properties and volumetric reserves.
The Role of DGThe Role of DG
in Reservoir Simulationin Reservoir Simulation
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rock properties and volumetric reserves.
RESERVES CLASIFICATIONS
• PROVED : – Estimated to reasonable certainty. Often based on
well logs but normally requires actual production or
formation tests. – Proved developed reserves – Reserves that are expected to be recovered from existing wells
– Proved undeveloped reserves
– To be recovered by new drilling, deepening wells to a newreservoir or where additional finance is required to produce
• PROBABLE RESERVES – Less certain than proved but can be assessed to
some degree of certainty. May include loggingestimates, improved recovery technique estimates
• POSSIBLE RESERVES
– Not as certain as probable reserves and can only beestimated to a low degree of confidence.
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• UNPROVED RESERVES Resources
RESERVES CLASSIFICATIONS
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Decision Making: protocol• Despite these defined terms, there is still some latitude in their
application. In general, we use this:
• Proved Reserves = minimum case economics. Financialinvestment is based on proved reserves.
• Proved + Probable Reserves = most likely caseeconomics. Internal company decisions usually based on this.
• Proved +Probable + Possible Reserves = maximum
case economics. This is the best that could reasonably happenfor a venture. Companies try to sell ventures based on this.
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MM DARISSALAM, YOGYAKARTA JUN. ‘08
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