well logging geophysics

By Ir. Djoko Wintolo, DEABy Ir. Djoko Wintolo, DEADepartment of Geological EngineeringDepartment of Geological EngineeringFaculty of EngineeringFaculty of EngineeringGadjah Mada UniversityGadjah Mada University

Lecture slides for Exploration Geophysics Lecture slides for Exploration Geophysics

Djoko Djoko WintoloWintolo

LOGGING

An activity to record the rock characteristics as a function of the

depth.Recording during drilling activities while there are a

mud and water materials is called as MUD LOGGING (lithological logging).

The recorded data: Rocks type, Hardness/ compaction, Fluid content.

Recording after drilling activities by using a wire line tool (instrument) named as WIRELINE LOGGING.

The recorded data: Rock Resistivity, Rock density. Mud cake thickness, Radioactivity of rocks, Acoustic properties, Formation temperatur, etc.


WIRELINE LOGGINGWIRELINE LOGGING

OPENHOLE LOGGINGOPENHOLE LOGGINGLogging in a well before completing phase Logging in a well before completing phase (before casing/ pipe construction).(before casing/ pipe construction).All of logging instruments can be worked.All of logging instruments can be worked.

CASEDHOLE LOGGINGCASEDHOLE LOGGINGLogging after well completing (casing Logging after well completing (casing construction) :construction) :Only for special instruments: Only for special instruments: - Gammaray-log- Gammaray-log- Caliper-log- Caliper-log- NMR- NMR- CBL- CBL


Data Analysis from Wireline LogData Analysis from Wireline Log

Objective / goal: Objective / goal:

Made an quantitative and Made an quantitative and qualitative interpretations from qualitative interpretations from logging data for identify the logging data for identify the productive / prospective layers. productive / prospective layers.


QUALITATIVE INTERPRETATIONQUALITATIVE INTERPRETATION

It is based on deflection pattern in the logging It is based on deflection pattern in the logging recorded paper which the curves are influenced by recorded paper which the curves are influenced by lithology and formation fluid content.lithology and formation fluid content.

To justified the lithology or rock layer formationTo justified the lithology or rock layer formation.. To detect the porous / permeable layers and To detect the porous / permeable layers and

estimate the rocks fluid contentestimate the rocks fluid content .. - - Estimate the oil, gas and water layer / Estimate the oil, gas and water layer /

formation.formation. - - Estimate the position of Estimate the position of GOC GOC // WOCWOC As a base data for qualitative interpretations.As a base data for qualitative interpretations.


QUANTITATIVE QUANTITATIVE INTERPRETATION INTERPRETATION

By using the equations or charts to By using the equations or charts to calculate the reservoir parameters calculate the reservoir parameters from log data from log data (Rw, Rt, (Rw, Rt, ΦΦb, b, ΦΦf, f, ΦΦm , dll)m , dll)

Porosity (Φ)

Water Saturation (Sw)

Saturation of Hydrocarbon remains (Shr)

Saturation of Hydrocarbon mobile (Shm)

Initial hydrocarbon reserve in volumetric form – Original/ Initial Oil In Place (OOIP/IOIP)


Types of LOGTypes of LOG

1.1. LITHOLOGIC LOGLITHOLOGIC LOG

2.2. RESISTIVITY LOGRESISTIVITY LOG

3.3. POROSITY LOGPOROSITY LOG


LITHOLOGIC LOGLITHOLOGIC LOG

Type of Log (instrument) which used Type of Log (instrument) which used to measure the lithology that are to measure the lithology that are drilled in well operation.drilled in well operation.

- SP - log- SP - log

- Gamma Ray - log- Gamma Ray - log

- Caliper - log- Caliper - log


RESISTIVITY LOGRESISTIVITY LOG Type of log (instrument) which used to Type of log (instrument) which used to

measure the resistivity value of rock.measure the resistivity value of rock.- Log SP- Log SP- Log Normal- Log Normal- Microlog- Microlog- Microlaterolog- Microlaterolog- Laterolog- Laterolog- Induction Log- Induction Log- MSF- MSF


POROSITY LOGPOROSITY LOG

Type of log (instrument) that Type of log (instrument) that measure or detect the porosity of measure or detect the porosity of rocks.rocks.

- Density - log- Density - log

- Neutron - log- Neutron - log

- Sonic - log- Sonic - log


The Lithologic description (mud-loggig) by a wellsite The Lithologic description (mud-loggig) by a wellsite geologist as a part of drilling reportgeologist as a part of drilling report


Some type of wireline logging ( records)Some type of wireline logging ( records)


Image Image scanner scanner logginglogging


UGIS-11 housing, made by RusiaUGIS-11 housing, made by RusiaDjoko Djoko WintoloWintolo

Logging for Logging for groundwategroundwater studyr study


Geochemical loggingGeochemical loggingDjoko Djoko WintoloWintolo

Process of Interpretation

• Identify potential reservoir intervals; distinguish non-permeable, non-reservoir intervals from porous potential intervals.

• Estimate thickness of the potential reservoirs. • Determine lithology (rock type) of the potential

reservoirs. • Calculate porosity (Φ). • Determine resistivity of formation water (Rw). • Calculate water saturations (Sw, Sxo) using

resistivity (Rt, Rxo). • Estimate in-place and movable hydrocarbons.


Resistivity logs do not always measure resistivity directly. Some resistivity logs (actually induction logs) measures conductivity instead which is thereciprocal of resistivity. 1 x 1000resistivity (ohms /m) = ------------ (millimhos/m) conductivity

Induction logs are used in wells drilled with a relatively fresh-water mud (low salinity) to obtain more accurate value of true resistivity.


Spontaneous Potential (SP log)

The SP log is a measurement of the natural potential difference or self potential between an electrode in the borehole and a reference electrode at the surface (problem with offshore wells, no ground). No artificial currents are applied.

Three factors are necessary to produce an SP current: 1. a conductive fluid in the borehole, 2. a porous and permeable bed surrounded by an impermeable formation, and 3. a difference in salinity (or pressure) between the borehole fluid and the formation fluid.


Nuclear logsNuclear logs

3 Principles:3 Principles:

1.1. Detection of Detection of γγ – radiation resulting from – radiation resulting from natural radioactivitynatural radioactivity

2.2. Measure absorption of Measure absorption of γγ -radiation emitted -radiation emitted by controlled by controlled γγ –source –source

3.3. Measure penetration of Measure penetration of γγ -radiation emitted -radiation emitted by controlled neutron sourceby controlled neutron source

Only Only γγ -r adiation and neutrons have -r adiation and neutrons have appreciable penetrating powerappreciable penetrating power


Thermal loggingThermal logging

1.1.To determine heat flow To determine heat flow (geothermal)(geothermal)

2.2.To locate thermal anomalies To locate thermal anomalies caused by fluid flowcaused by fluid flow

3.3.Abnormal radioactivityAbnormal radioactivity4.4.Oxidation regionsOxidation regions


Well-logging in coal explorationWell-logging in coal exploration


Thanks YouThanks You


ReferensiReferensi1. Asquith, George B, 1. Asquith, George B, Log Evaluation of Shaly Sandstone: Log Evaluation of Shaly Sandstone:

A Practical GuideA Practical Guide, The American Association of Petroleum , The American Association of Petroleum Geologists, Tulsa Oklahoma. Geologists, Tulsa Oklahoma.

2. Desbrandes, R, 2. Desbrandes, R, Encyclopedia of Well LoggingEncyclopedia of Well Logging, Gulf , Gulf Publishing Company Book Division, Houston, Texas, 1985.Publishing Company Book Division, Houston, Texas, 1985.

3. Dewan, John T, 3. Dewan, John T, Essential of Modern Open-Hole Log Essential of Modern Open-Hole Log InterpretationInterpretation, Penn Well Publishing Company, Tulsa , Penn Well Publishing Company, Tulsa Oklahoma, 1983.Oklahoma, 1983.

4. Harsono Adi, 4. Harsono Adi, Evaluasi Formasi dan Aplikasi Log.Evaluasi Formasi dan Aplikasi Log.5. Helander, Donald P, 5. Helander, Donald P, Fundamental of Formation Fundamental of Formation

EvaluationEvaluation, OGCI Publications, Oil and Gas Consultants , OGCI Publications, Oil and Gas Consultants International Inc, Tulsa, 1983.International Inc, Tulsa, 1983.

6. Pirson, Sylvain J, 6. Pirson, Sylvain J, Well Log Analysis for Oil and Gas Well Log Analysis for Oil and Gas Formation EvaluationFormation Evaluation, Prentice Hall, Inc Englewood Cliffs, , Prentice Hall, Inc Englewood Cliffs, New Jork, 1963. New Jork, 1963.

7. Wyllie M.R.J, 7. Wyllie M.R.J, The Fundamental of Well Log The Fundamental of Well Log InterpretationInterpretation, 3th Edition Academic Press, Inc 1963., 3th Edition Academic Press, Inc 1963.


well logging geophysics

Documents

sp log

density log

neutron log

log data rw

log sp log normal microlog

logging data

gamma ray log

lithology rock type