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Transcript of Process Training
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ByAmmad Baig
Upstream Oil Production ProcessTraining
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Oil Exploration and Production
Upstream
The upstream sector includes thesearching for potential underground or
underwater oil and gas fields, drilling ofexploratory wells, and subsequentlyoperating the wells that recover andbring the crude oil and/or raw natural
gas to the surface [2]
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Oil Exploration and Production
Midstream
Midstream operations are usually included in thedownstream category. The midstream industry
processes, stores, markets and transportscommodities such as crude oil, natural gas,natural gas liquids (LNGs, mainly ethane,propane and butane) and sulphur.
Downstream
The downstream sector includes oil refineries,petrochemical plants, petroleum productdistribution, retail outlets and natural gasdistribution companies
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Upstream Process
Offshore and Onshore Reservoirs
Well Formation
Collection of Crude Oil from Wells
Separates Gas
Oil Processing to remove
Sulfur
Water
Salts
Shipping oil to storage facilities
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GS Process OIL Flow
WellsReceiverManifold
ProductionSeparators
ChargePumps
CrudeHeaters
FWNO,DESALTERSTreater
SurgeTank
ShippingPumps
Metering
LauncherManifold
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Oil Reservoirs
A petroleum reservoir or an oil and gasreservoir, is a subsurface pool ofhydrocarbons contained in porous rock
formations. The naturally occurringhydrocarbons are trapped by overlying rockformations with lower permeability [2]
These formations occur over a period of
millions of years. A young reservoir is saidto be 60 million years old. Older reservoirshave better API Oil Grade. [1]
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Oil Reservoir
Seismic data and advancedvisualization 3D models are used toplan extractions. Normally a well willprovide 30 - 60 % extractions.However by using EOR (Enhanced OilRecovery) techniques 70 % can be
achieved. [1]
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Oil Wells and Reservoir Engg.
The well sits on the actual oil/gasreservoir:
1.)Oil Wells
2.)Gas Wells
3.) Condensate Gas wells
Various types of wells:
1.) Subsea
2.) Onshore
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Structure of Oil Well
Well Casing: Series of metal tubes installed in a
freshly drilled hole. It strengthens thesides of the hole, ensures nohydrocarbons leak out or seep into thewall formation. The type of casingdepends upon the depth, temp, pressureand formation of the well. Casing is
usually cemented in place. [2] Usually the diameter of the well
decreases as it is dug deeper leading toa type of colonial shape. [1]
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Casing Structure
Conductor Casing
20 50 feet long
Surface Casing
100 400 meters long
Intermediate Casing
Longest casing string
Production Casing
Oil string, connects oil reservoir to surface casings
A packer is used between casing andtubing at the bottom of the well.
Structure of Oil Well
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Structure of Oil Well Completion:
Refers to process of finishing the well forproduction. This principally involves preparingthe bottom of the hole to the requiredspecifications, running in the production tubing
and its associated jewellery and perforating andstimulating as required. Following are a few types of completion. Open Hole completion Perforated Completion
Sand Exclusion Completion Permanent Completion Multiple Zone Completion Drain Hole Completion
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Completion After drilling and casing the well, it must be 'completed'. Completion is the
process in which the well is enabled to produce oil or gas. In a cased-hole completion, small holes called perforations are made in the
portion of the casing which passed through the production zone, to providea path for the oil to flow from the surrounding rock into the production
tubing. In open hole completion, often 'sand screens' or a 'gravel pack' isinstalled in the last drilled, uncased reservoir section. These maintainstructural integrity of the wellbore in the absence of casing, while stillallowing flow from the reservoir into the wellbore. Screens also control themigration of formation sands into production tubulars and surfaceequipment, which can cause washouts and other problems, particularlyfrom unconsolidated sand formations in offshore fields.
After a flow path is made, acids and fracturing fluids are pumped into thewell to fracture, clean, or otherwise prepare and stimulate the reservoir
rock to optimally produce hydrocarbons into the wellbore. Finally, the areaabove the reservoir section of the well is packed off inside the casing, andconnected to the surface via a smaller diameter pipe called tubing. Thisarrangement provides a redundant barrier to leaks of hydrocarbons as wellas allowing damaged sections to be replaced. Also, the smaller diameter ofthe tubing produces hydrocarbons at an increased velocity in order toovercome the hydrostatic effects of heavy fluids such as water.
In many wells, the natural pressure of the subsurface reservoir is high
enough for the oil or gas to flow to the surface. However, this is not alwaysthe case, especially in depleted fields where the pressures have beenlowered by other producing wells, or in low permeability oil reservoirs.Installing a smaller diameter tubing may be enough to help the production,but artificial lift methods may also be needed. Common solutions includedown hole pumps, gas lift, or surface pump jacks. Many new systems in thelast ten years have been introduced for well completion. Multiple packersystems with frac ports or port collars in an all in one system have cutcompletion costs and improved production, especially in the case of
horizontal wells. These new systems allow casings to run into the lateralzone with proper packer/frac port placement for optimal hydrocarbonrecovery.
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Wellhead
The wellhead consists of pieces of equipment mounted at theopening of well to regulate and monitor the extraction ofhydrocarbons from underground formation.
A wellhead consists of three components The casing head
At the bottom. Connected to hanger. Gives access to open, close, bled down and in some caseproduce through casing as well.
Used to determine leaks in casing, tubing or packer.
The tubing head and tubing hanger: This is the component, which sits on top of the wellhead and
serves as the main support for the production tubing
The Christmas tree Master gate valve, a pressure gauge, a wing valve, a swab
valve and a choke Downhole Safety Valve:
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Christmas Tree
The set of valves, spools and fittings connected to the top of a wellto direct and control the flow of formation fluids from the well
Christmas tree. Christmas trees are found in a wide range of sizesand configurations, depending on the type and productioncharacteristics of the well. In each case, the Christmas treeprovides primary and back-up control facilities for normal
production and wellbore shut-in. The Christmas tree alsoincorporates facilities to enable safe access for well interventionoperations such as slickline, electric wireline or coiled tubing.
The primary function of a tree is to control the flow into or out ofthe well, usually oil or gas. A tree often provides numerousadditional functions including chemical injection points, wellintervention means, pressure relief means (eg annulus vent), treeand well monitoring points
The CONTROL SYSTEM attached to the tree controls the downholesafety valve, while the tree acts as an attachment and conduitmeans of the control system to the downhole safety valve.
Subsea trees are available in either Vertical or Horizontalconfigurations with further speciality available such as Dual Bore,Monobore, concentric, Drill-Through, Mudline, Guidlineless orGuideline
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Drive Mechanisms
A good reservoir will have sufficientpressure to push hydrocarbons to thesurface by itself. However as thepressure is released the productionwill drop. To maintain that productionvarious methods are employed.
1.) Gas Injection 2.) Water Injection
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Water Injection
The water injection method used in oilproduction is where water is injected backinto the reservoir usually to increasepressure and thereby stimulate production
Water is injected for two reasons: 1. Forpressure support of the reservoir (alsoknown as voidage replacement). 2. Tosweep or displace the oil from thereservoir, and push it towards an oil
production well. [2] Water Sources: 1.) Sea Water 2.) Produced
Water
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Water Injection Process
Water is passed through filters to remove impurities. Thefiltration is up to 2 micrometers in various steps. Sand Filtration Salts Filtration
De-oxygenation
From the filters water is fed to de-oxygenation tower.Oxygen is removed to minimize corrosion or any bacterialgrown.
De-oxygenation tower brings the injection water intocontact with a dry gas stream. The filtered water drops intothe de-oxygenation tower, splashing onto a series of trays,causing dissolved oxygen to be lost to the gas stream.
As a backup, an alternate method is to add SodiumBisulfate to water source.
High Pressure, High Flow pumps are used to inject water intothe reservoir. They fill the bottom of the reservoir to push theoil towards the well.
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Well Test
Rizwan Saeed
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Artificial lift
Plunger Lift
Rod Pumps
Downhole pumps
ElectricalSubmersible pumps
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Production Separator
The well stream consists of crude oil, gas,condensates, water and various contaminants. Thepurpose of the separators is to split the flow intodesirable fractions.
Gravity type production separator [1]
Various Stages of separation can be designeddepending upon hydrocarbons and condensateformation in wells
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Production Separator
Slug catcher will reduce the effect of large gasbubbles and liquid plugs.
Oil Level Control
Gas Pressure Control
Prevent Blowout in Separator Prevent High Pressure in Vessel
PIT
LIT
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Electrostatic Desalter
A desalter is used to removeunacceptable amount of salts in theseparated oil.
Various stages of desalters can beused depending upon the amount ofsalts in oil.
The electrostatic desalters useelectrodes to separate salts ofsodium, calcium and magnesium.
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Desalter Operation
Fresh water addition provides dilution
Coalescence to promote droplet growth
Phase separation to remove contaminants
Combined AC/DC fields provide bettercoalescence and electrolytic nature fordesalting.
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Free Water Knockout
A vertical or horizontal separator used mainly to removeany free water that can cause problems such as corrosionand formation of hydrates or tight emulsions, which aredifficult to break
A free-water knockout is commonly called a three-phaseseparator because it can separate gas, oil and free water.The liquids that are discharged from the free-waterknockout are further treated in vessels called treaters.Free-water knockout is abbreviated as FWKO.
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Surge Tank
Surge tank is a vessel placed in aflowline through which liquids orgases are flowed to neutralize sudden
pressure surges.
A surge tank is usually a large vessel.
It is located downstream of the
Production Separators, Treaters,FWKO and desalters.
It is located upstream of Shipping
pumps.
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Charge Pumps and Shipping Pumps
Charge pumps are located in downstreamof Production separators.
Charge pumps are usually upstream ofCrude oil heaters
Shipping pumps pump oil from oneplatform to another platform.
Shipping pumps pump oil from surge tanksthrough long distance or short distance
pipe lines from offshore/on shore platformsto oil storage facilities. Back pressure control is required on
shipping pumps for maximum efficiency.
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Metering Skids
Orifice plate Meters
Rotary Meters
Ultrasonic meters
A metering skid isdivided into severallines in parallel toprovide accurateand redundantmetering
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GS Process GAS Flow
Wells ReceiverManifold
ProductionSeparators
FlareScrubber
Over Pressure Protection(Desalters, FWNO, Surge Tank, e.t.c.)
GasComp
Metering
LP GasLift
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Flare/Vent Scrubber
A scrubber is designed to remove small fractions ofliquid from gas
A vent scrubber is a two phase separator designed toremove liquid from the relieving fluids before the gasis flared or vented. The liquid is returned to the
process. Incase of GSN the liquid from flare scrubber is fed
back to Surge tank for shipping. A pipe that releases gas to atmosphere is called vent.
If the gas is burned at the tip of vent it is called aflare.
Applicable air pollution control regulations must bemet when venting. Flaring should be done whenreleasing H2S to atmosphere.
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Gas supply to Utilities
ProductionSeparator
GasComp
Stage 1
GasComp
Stage 2
GasComp
Stage 3
FilterSeparator
GlycolContactor
HP FUELGAS SCRUB
GASLIFT
MP FUELGAS SCRUB
MP GASCONDITIONING
FUELGAS
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Gas Compression
Gas passes through following equipmentfor compression:
Cyclotube Separator
Separator Filters
Heat Exchanger
Turbine Compressor
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Temp Control and Dehydration
Methanol is injected in flow lines toprevent Hydrate formation andprevent corrosion. Hydrates form and
freeze to hydrate ice that may upsetprocess and damage equipment andpipes.
For normal risers, hydrates form only
when production stops and the tempstarts to drop.
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Glycol Dehydration System
GlycolContactor
Tower
Gas Inlet
Gas outlet
HeatExchanger
Pumps
GlycolReboiler
Condensateseparator
HeatExchanger
HeatExchanger
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Associated Processes
Gas Injection
Gas Compressors
Glycol Unit Reboiler
Heat Exchanger
Methanol Injection
Water Injection
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Misc Operations
Oil sampling unit
Refined oil/water separation (Wemco)
Fuel gas supply for generators
Water treatment
Air compressors for platform air
supply
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Oil Sampling
An Oil Sampler is used to check thequality of Oil.
Usually an Oil Sampler is installedupstream of shipping pumps.
A common oil sampler consist of ansampling tank, injector and a pump.
The sampling time depends uponRate of Flow in the shipping line.
Welker Sampler
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Welker Sampler
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WEMCO
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Water Treatment
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References
1. Oil and gas Production Handbook
2. www.Wikipedia.org
3. Petroleum and Natural Gas Engineering
Handbook4. Design of Oil Handling System and
Facilities
5. Surface production operations
6. http://www.natcogroup.com/Content.asp
7. http://www.glossary.oilfield.slb.com/
http://www.wikipedia.org/http://www.natcogroup.com/Content.asphttp://www.natcogroup.com/Content.asphttp://www.wikipedia.org/