Well Logging by Group1

7/28/2019 Well Logging by Group1

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Well Logging and Its

Implication in

Reservoir Simulatio

Submitt


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Group Members

Name Roll no.

Satyam Prasad 10BPE-012Yakshender 10BPE-014

Utkarsh Bhushan 10BPE-017

Nimish Newatia 10BPE-018

R. Vellayan 10BPE-024

Disha Sahoo 10BPE-058

Krishnaraj Singh 10BPE-079

Prashant Kumar 10BPE-087

Sumantha Reddy 10BPE-097

Aman Dhanani 10BPE-100


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What is well Logging?

Well log is a continuous record of

measurement made in bore holerespond to variation in some

physical properties of rocks through

which the bore hole is drilled.

Traditionally Logs are display on

girded papers shown in figure.

Now a days the log may be taken as

films, images, and in digital format.


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History

Key Events in history:

1912Conrad Schlumberger give the idea of using electrical measurem

map sub-surface rock bodies.

1919ConradSchlumberger and his brother Marcel begin work on we

1927First electrical resistivity well log was taken.

1930Dip Meter log were developed.

1936Photographic-film recorder was developed.

1941Gamma Ray and Neutron Log were used for first time.


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Why Are Well Log So Important?

They Help us to:

To Identify Reservoir Rocks

To identify the productive zones of hydrocarbon.

To define the petro-physical parameters like porosity, permeability, hyd

To measure hydrocarbon mobility.

To identify fluid saturation in reservoir.

To determine depth, thickness, formation temperature and pressure of a

To analyze various other geological parameters like formation dip.


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Open Hole Logging

Open-Hole logging refers to logging operations that are performed on a

the wellbore has been cased and cemented. In other words, the logging

through the bare rock sides of the formation.

This is the most common type of logging method because the measuremobstructed and it's done during or after the well has been drilled.


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Cased Hole Drilling

Cased-Hole logging involves retrieving logging measurements through th

or the metal piping that is inserted into the well during completion operatiohole logging is performed more rarely but still provides valuable informati

well.

Cased-hole logging is used to help operators obtain additional information

reservoir that has already been completed.

Cased-hole logging can be used to evaluate the formation and completion o

well as determine the state of the cement, corrosion and perforation


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Production Logging

Production logging denotes that area of well logging concerned with two g

problem well diagnosis, and reservoir surveillance.

Production logs are for analyzing wells already in production, with knownin place, or for looking for accessibility to inject to create drive mechanism

Logging in exploration uses the same concept, but those logs are looking aformation to see if it is conducive to hydrocarbon production.

The purpose of logging is to track fluid movement within or behind pipe othe movement of reservoir fluid contacts.


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Characterization of Well-Log

Logs are recorded to measure different physical parameter of the well.

also known as the electronic eye of the well.

Depending upon need many different parameters are considered, howe

a very few basic parameters, which are broadly classified as:

Resistivity log.

Porosity/ Radioactive log.

Sonic/ Acoustic log.

Sampling and coring.

Cement/ Mud evaluation log.


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Open Hole Logging

There are various logging tools available to evaluate the sub-surface conditions in

namely they are:

Porosity logs.To determine porosity of sub-surface rock of

interest.

Permeable zone logs.

Evaluate the permeable zone.

Resistivity logs.

Electric resistivity in the formation.

Spectral logs.

Content of special radioacti

Dipmeter and related logs.

High resolution resistivity gbedding and cracks

Caliper logs.

Borehole diameter and its s


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Gamma Ray Log

The Gamma Ray log is a continuous measurement of thenatural radioactivity emanating from the formations.

It works on the principle that clay particles containsmore concentration of high radioactive materials andhence shales show high radioactivity due to presence ofisotopes emitting radiation are Potassium-40, Uranium,and Thorium (K40, U, Th).

Sensitive detectors count the number of gamma rays perunit of time

Recorded in API Units which is 1/200th of thecalibrated, standard response.

This log can be used in all open hole cased hole andproduction logging.


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Self-Potential Log

The spontaneous potential tool records the naturally

occurring electrical potential produced.

The SP curve reflects a difference in the electrical

potential between a movable electrode in the borehole

and a fixed reference electrode at the surface

Though the SP is used primarily as a lithology indicator

and as a correlation tool, it has other uses as well.

permeability indicators.

shale volume indicator

porosity indicator, and

measurement of Rw.


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Caliper Log

Used to measure the variation of borehole diameter with depth.

Give the bore hole cross-sectional variation.

It is one of most simple tools.

Application:

High-resolution Lithology discrimination

Depth calibration of different log suites

Fracture identification Measurement of borehole rigidity.

Estimation of mud cake thickness.

The evaluation of temperature and CBL logs in combination with caliper data

help to diagnose quality of cementation


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Resistivity Log

Working Principle: The resistivity of a substance is its ability to impede the

electric current through the substance.

Formation resistivity general range 0.2 to 1000 ohm meter.

For a formation with oil or gas, both are which electrical insulators resistiv

function of formation factor, brine resistivity and water saturation.

Types (depending on environment):

Latero Log.

Induction Log.


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Resistivity Logs (contd.)

Application of resistivity Log:

True formation resistivity and flushed zone resistivity

Mud filtrate invasion profile

Quick look hydrocarbon detection

Indication of producible hydrocarbon

Correlation of different formations


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Neutron Log

Working principle: Gamma ray spectrum analysis

emitted on collision of neutrons to nucleus of atoms inthe formation.

Americium-Beryllium/Neutron bulb emits neutrons ascontinuous source of energy

Neutrons collide with nucleus of atoms in formation

and looses energy. When come back to normal state,emits Gamma ray.

Analysis of Gamma ray spectrum identifiescomposition of elements into the formation viz. C, H,Cl, O, etc.

Source: R


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Neutron Log (Contd.)

Advantages of Neutron Log:

Determination of Porosity

Lithology identification

Water saturation

Gas detection

Location and monitoring of gas/oil and water/oil contacts.

Correlation with open hole resistivity logs

Shale indicator


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Sonic/Acoustic Log

Working principle: time difference measurement to travel

an acoustic wave through on foot formation.

It is ensured the wave travels along a parallel path to the

borehole

The time difference measured is reciprocal of the

velocity of compression sound wave.

Wyllie proposed the following empirical relation fordetermination of porosity form the sonic log.

Source: Referen


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Sonic/Acoustic Log (Contd.)

Advantages:

Effects of cement coverage can be

easily measured by comparing both

open and case hole dia.

Detection of hydrocarbon in high

porosity sand.

Lithology can be identified.

Integrated travel time useful in

seismic interpretation.

Limitations:

In unconsolidated forma

formation fractures.

Provides less working e

presence of Gas saturati

aerated mud.


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Density Log

Principle: Measurement of formation bulk density and photo

electric absorption index of the lithological column.

The density depends on fluid density and matrix density in porousformation.

The detectors measure the gamma rays flux resulting from

scattering and absorption effect of the formation.

The higher the formation density, the lower the gamma rayintensity at the detectors.


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Cased Hole Logging

There are various tools available like:

Casing Collar Locator Log Locates the casing collar.

Cement Bond Logging Tool. Evaluate cement bonding.

Perforation Tool. For controlled explosion.

Bridge Plug Setting Tool.To plug the casing to isolate it.

Tubing Puncture.

To puncture the tube.

Casing cutting/ Tubing C

Sub-surface cutting of cas

String Shot.

Acid Job.


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Casing collar locator Tool

It is a magnetic device that detects changes in metal mass, such as

those induced by the relatively high mass of casing collar vis--visthe casing.

The disturbance to the magnetic field is detected as a voltagedifference

The CCL detects changes in metal volume a it moves through thetubing or casing.

Purpose: to determine the location of casing collars

Application: Depth correlation

Source: Refere


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Cement Bond Tool

It evaluates cement bond integrity.

It has single Omni-directional acoustic transmitter and two receivers. O3ft and other at 5ft.

It works based upon the principle of sonic wave-train attenuation, detec

the amplitude of a sonic signal passing along the casing as an analog

waveform.

Signal is reduced where the casing is bonded to the cement. Clearlyidentifying cement bond.

Purpose: Cement bond integrity is requisite to hydraulic isolation

Application: Cement bond evaluation

Source:


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Perforation Tool To establish fluid communication between well bore and formation for

injection.

Uses high explosives with shaped charges.

Perforators uses

Initiator/ Detonator

Detonating chord

Shaped Charges

Types:

Overbalanced method (+ve head)

Underbalanced method (- ve head)

Source: Refere


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Bridge plug setting by wire line

Bridge plug are mainly used for isolation of zones in casing

This prevent the movement of fluid from either direction.

Back off services Some times the drill string or tubing gets stuck in bore hole

A shock at a joint just above free point is given

When detonating chord is fired it releases string

Puncture Job

It is a perforation operation with specially design small change so as to have big h

depth of penetration.


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Production Logging

Various types of tools used in production logging are basically:

Radioactive fluid density tool

Production gamma ray tool

Capacitance temperature flow meter

Caliper Log

Temperature Tool Log.


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Radioactive Fluid Density Tool

Working principle: The density tool responds to electron density of the fluid in

Used to differentiate the various types of fluid in the bore-hole depending on t Tool measures borehole fluid density by radioactive techniques.

Part of the fluid flow passes through the tool between low activity Cs 137 gam

a Scintillation gamma ray detector.

An increase in the average fluid density in the sample volume causes a reducti

counts.

Purpose: Is to measure fluid density of a sample as it flows through the tool

Applications:

Multiphase production drilling

Fluid identification

Horizontal/ Highly deviated wells

High fluid flow rates.


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Production Gamma Ray Tool

It comprise a sodium iodide scintillation crystal and

photomultiplier to measure incident gamma radiations. Single conductor passing through the tool carries telemetry and

power.

The detector is unshielded and will thus accept radiation from

any direction.

Purpose:

Lithology identification and depth correlation

Gravel pack density monitoring

Evaluation of shale volume.

Delineation of nonradioactive mineral including coal beds.


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Capacitance Temperature Flow meter

Purpose: to provide a continuous log of fluid capacitance (water hold up

temperature, flow-rate and flow direction

Application:

Fluid composition form average dielectric constant

Fluid ID from temperature response

Location of leaks and cross-flow by temperature response

Production and injection log interpretation

Cement top determination


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Temperature Logging

Oldest type of production log to measure temperature.

Early thermometers have mercury as the sensing element whose expansi

contraction positioned a floating piston.

Later the sensors were replaced by vapor pressure type detectors.

This type of thermometers comprises of a bulb filled with volatile liquid

vapor pressure changes with temperature.

This is still in use mainly for bottom-hole temperature measurements.


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Reservoir Simulation

It is a practice for preparing a model of the reservoir existing below t

subsurface and defining parameters such as porosity and permeabilityetc. for every point in the reservoir.

Done by combining physical, mathematical, geological data by comp

programming

Needed to obtain performance predictions for a hydrocarbon reservoi

different operating conditions.


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Modeling Methods

Divide the reservoir into small cubes.


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Reservoir Structure

Each small cube is analyzed by different techniques.

The techniques are dependent on the scale of the cube size.

Different scales are as follows:

1. Giga Scale

2. Mega Scale

3. Macro Scale

4. Micro Scale


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Scaling

Giga Scale: Includes information associated with geophysical techni

reservoir architecture. Theories of regional characterization such as ptectonics provide an intellectual framework.

Mega Scale: It is the scale of reservoir characterization and include wwell testing and 3D seismic analysis

Macro Scale: It focuses on data sampling at the level of core analysiproperty analysis

Micro Scale: Includes pore scale data obtained from techniques suchsection analysis and measurements of grain-size distribution


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Well logging and its implication in Res

Simulation

It is a technique that comes undermega scale.

The mega scale is the scale at which we begin to inte

well log and well test data into a working model of r

Well logging gives us following important data for r

simulation:

Rock type

Fluid type

Water and hydrocarbon saturation


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Logging derived parameters aiding in

characterization

LOG TYPE USED FOR

Gamma ray Rock type

Resistivity Fluid type

Density Porosity

Acoustic (Sonic) Porosity

Neutron Hydrogen Conten

Spontaneous Potential Permeable Beds


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Resistivity Logs Used for determining Rock type

Detects shale from in situ radioactivityHigh GR => Shales

Low GR => Clean sands or carbonates

Gamma Ray Logs

Used for Fluid type Measures resistivity for formation water

High resistivity => Hydrocarbons

Low resistivity => Brine


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Density Log Used for finding porosity

Measures electron density by detecting Compton scattered gamma rays. Edensity is related to formation density.

Good for detecting HC gas with low density compared to rock or liquid.Low response => Low HC gas contentLarge response => High HC gas content

Neutron log: Used to determine Hydrogen content

Fast neutrons are slowed by collisions to thermal energies. Thermal neutrcaptured by nuclei, which then emit detectable gamma rays.

Note: Hydrogen has a large capture cross-section for thermal neutrons.

Good for detecting gas.Low response => high H content

Small response => low H content


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Acoustic (sonic) log Used to measure porosity of the rocks.

Measures speed of sound in medium.

Speed of sound is faster in rock than in fluidLong travel time => slow speed => large pore space

Short travel time => high speed => small pore space

Spontaneous Potential

Used for determining permeability of beds. Measures electrical potential (voltage) associated with the movement of ions.

Low response => impermeable shales

Large response => permeable beds.


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Pressure logs (400C)To estimate flow irrigate of the bedrock which is governe

permeability of the rock, the viscosity of the liquid and

distribution of pressure.

Down hole Video Camera (80C)

Motion pictures can be taken down to 600 m depth if thetemperature is not higher than 80C. This equipment is u

studies of fractures, scaling, and casing damage hence us

geological description.


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Televiewer Detects the surroundings, detect shape, formation, fract

casing damage, and other irregularities in the well and i

surroundingsso useful in geological description.

Fluid FlowThe continuous flow-meter spinner is logged to obtain an

picture of inflow zones within the borehole hence useful

characterization.


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References

1. Principles of Applied Reservoir Simulation, John R. Franchi

2. Basic applied Reservoir Simulation by T. Ertekin, Jamal H. Abou-Kassem, and G. R. King

3. https://www.slb.com/news/inside_news/2013/~/media/Files/resources/oilfield_review/ors11

ogging.ashx

4. http://www.geo.wvu.edu/~jtoro/petroleum/15_logs.pdf

5. http://www.Usgs.gov.in

6. http://www.spec2000.net

7. http://www.Worldoil.com

8. http://www.Vniigis.bashnet.ru 9. http://www.petrolog.net

10. http://www.bittooth.blogspot.com
https://www.slb.com/news/inside_news/2013/~/media/Files/resources/oilfield_review/ors11/spr11/defining_logging.ashxhttps://www.slb.com/news/inside_news/2013/~/media/Files/resources/oilfield_review/ors11/spr11/defining_logging.ashxhttp://www.geo.wvu.edu/~jtoro/petroleum/15_logs.pdfhttp://www.usgs.gov.in/http://www.spec2000.net/http://www.worldoil.com/http://www.vniigis.bashnet.ru/http://www.petrolog.net/http://www.bittooth.blogspot.com/http://www.bittooth.blogspot.com/http://www.petrolog.net/http://www.vniigis.bashnet.ru/http://www.worldoil.com/http://www.spec2000.net/http://www.usgs.gov.in/http://www.geo.wvu.edu/~jtoro/petroleum/15_logs.pdfhttps://www.slb.com/news/inside_news/2013/~/media/Files/resources/oilfield_review/ors11/spr11/defining_logging.ashxhttps://www.slb.com/news/inside_news/2013/~/media/Files/resources/oilfield_review/ors11/spr11/defining_logging.ashx

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