Oleh:

Dr. Ir. Eko Widianto, MT

Jurusan Teknik GeologiFakultas Teknologi Kebumian dan Energi Universitas TRISAKTI

2012

LECTURE MATERIALS

1. INTRODUCTION (1X) a. Definitionb. Geophysical Methods and their main applicationsc. Level of Petroleum Investigation

2. REFLECTION SEISMIC (5X) a. Fundamental of Seismic Reflection Methodb. Acquisitionc. Processingd. Interpretatione. Exercise

1. GRAVITY (3X) a. Introduction and general application of gravity datab. Paradigm Shift in Gravity data utilizationc. Gravity and Petroleum Systemd. Time-Lapse Microgravity Technology for Reservoir Monitoring

2. MAGNETIC (1X) a. General Application of Magnetic Data

LECTURE MATERIALS

1. INTRODUCTION (1X) a. Definitionb. Geophysical Methods and their main applicationsc. Level of Petroleum Investigation

2. REFLECTION SEISMIC (5X) a. Fundamental of Seismic Reflection Methodb. Acquisitionc. Processingd. Interpretatione. Exercise

1. GRAVITY (3X) a. Introduction and general application of gravity datab. Gravity data analysis for Oil and Gas Explorationc. Paradigm Shift in Gravity data utilizationd. Gravity data analysis for Oil and Gas Reservoir Monitoring (Time lapse)

2. MAGNETIC (1X) a. General Application of Magnetic Data

EXPLORATION PHASE

DEVELOPMENT & PRODUCTION

PHASE

Frequently used Frequently used of of geophysical methods geophysical methods for surface recording and typical applicationfor surface recording and typical applicationGeophysical method

Physical property measured

Typical applications Comment on applicability

Seismology Seismic wave velocity, seismic impedance contrast, attenuation, anisotropy

Delineation of stratigraphy and structures in petroleum exploration

Exploration seismology is the most widely used geophysical method in petroleum exploration.

Gravity Surveys Rock density contrast Reconnaissance of large-scale density anomalies in petroleum and mineral exploration

Gravity survey are generally less expensive but have less resolving power than seismic exploration.

Magnetic Surveys Magnetic susceptibility or the rock’s intrinsic magnetization

Reconnaissance of the crustal magnetic properties, especially for determination of basement features

Aeromagnetic surveys are widely used in both petroleum and mining application for determining large, deep structure.

Electrical and electromagnetic surveys

Rock resistivity, capacitance, and inductance properties

Mineral exploration These methods are used most frequently in mining exploration and well logging (resistivity, SP, and induction log)

(Lines and Newrick, 2004)

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GRAVITY AND MAGNETIC ANALYSIS CAN ADDRESS VARIOUS PETROLEUM ISSUES (1)

ISSUE GRAVITY & MAGNETIC TASK INTEGRATED WITH

Source Rock Deposition Where were the source rocks deposited? How deep are the source rocks?

Depth to magnetic basementRegional basin enhancements

Seismic dataRegional geology

Source Maturation Where are the “cooking pots” and fetch

areas? What is the present-day heat influx into

the basin and how much dose it vary? What is the thickness of the crust? What is the overburden?

Depth to magnetic basementIsostatic residualSediment thicknessDepth versus density modelingRegional structural modelingCurie point (regional heat flow)Delineation of volcanic

Seismic dataWell dataDensity and Velocity dataHeat-flow data

Hydrocarbon Migration How much relief is there on the

basement? What are the “shape” of the “cooking

pots”? Are major vertical conduits near surface

areas? Are major lineations present and how do

they relate with more recent geologic features?

Magnetic inversionDepth to magnetic basementVertical fault identificationGradient analysisRegional depocenter and sediment path enhancement

Well and outcrop dataTopographyRemote sensingSeismic dataSequence stratigraphic analysisSeismicity

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GRAVITY AND MAGNETIC ANALYSIS CAN ADDRESS VARIOUS PETROLEUM ISSUES (2)

ISSUE GRAVITY & MAGNETIC TASK INTEGRATED WITH

Reservoir PredictionWhere are the thickest sediment?Where are the highest sand probability?Where was the sources of sedimentation?What is the influence of tectonic on deposition?Have the sediment depocenters shifted over time?What is the compaction history of the sediments?Do the sands have lateral continuity and connectivity?

Depocenter and sediment path enhancement.Integrated basin modelingDensity inversionProvenance (magnetic lithology) determinationSedimentary magnetic analysisPaleomagnetic analysisIntegrated velocity analysis (2-D and 3-D)

Seismic data

Lithology data (outcrop and well)Sequence stratigraphic analysisBiostratigraphic data

TrapWhere are the major structures?What is the structural grain?Are faults in the sedimentary section?Are lateral porosity changes present?

Residuals and enhancements2-D/3-D structural/stratigraphic modelingFault identification – gradient analysisStructural inversionDensity inversion

Seismic dataOutcrop informationTopographyRemote sensingSeismicity

Development and Production Phases:Problem statement

1. How we can build reservoir model accurately?

2. How we can monitor and image the dynamic properties of reservoir until field termination?

3. How we can optimize production?4. How we can improve the Recovery

Factor?

What reservoir properties do we want to predict?

The critical reservoir characteristicThe critical reservoir characteristic

Static properties:1. Fluid phase (oil and gas

percent)2. Areal extent of the trap3. Depth4. Thickness5. Compartmentalization6. Reservoir net to gross7. Porosity

Dynamic properties:

1. Well deliverability2. Reservoir

connectivity3. Permeability4. Pressure change5. Phase change6. Reservoir

compaction

GeologicalModel

GeophysicalModel

GeochemicalModel

Petrophysical

Model

GeomechanicalModel

FluidModel

ProductionLoggingModel

TracerModel

Well testModel

RESERVOIRMODEL

RESERVOIRMODEL Tracer

Data

ProductionLogging

Data

FluidData

GeomechanicalData

PetrophysicalData

GeochemicalData

GeophysicalData

Well testData

Geological Data

Multi-diciplin approach for reservoir model

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Project Project phasephase

Critical subsurface Critical subsurface informationinformation

Technology Technology IInvolvementnvolvement

1) Exploration Proven Petroleum System and Play Resources information

Geophysics Geology Concept Drilling

2) Delineation Total hydrocarbon volume Areal limits of petroleum reservoir Deliverability

Geophysics Geology Concept Drilling Reservoir

3) Development

Compartmentalization Exact locations of development wells

Geophysics Development Geology Drilling Reservoir

4) Production Hydrocarbon saturation and pressure changes Flow restrictions and channeling

Production Reservoir Geophysics

Some aspects which drive gravity utilization

Improve Recovery FactorHardware / InstrumentationMulti Dicipline ApproachEfficient Time Lapse Technology for Reservoir MonitoringProblems in Geophysical Acquisition due to Geological conditionsSocial Problem

http://www.ldeo.columbia.edu/res/pi/4d4/what-is.html

http://www.ldeo.columbia.edu/res/pi/4d4/what-is.html

TACTICS Regional reconnaissance

Petroleum system analysis

Play analysis

Establishing exploration focus and G&G expenditure

Prospect identification and risk assessment

Lease and G&G acquisition

Tectono- stratigraphic framework

Basin Modeling

Prospect Risk reduction

Drill-site decision (less complex prospect)

Asset delineation and development

Drill-site decision ( complex imaging)

Reservoir performance monitoring

Enhance recovery

Gibson, R.I. & Millegan, P.S.; 1998

Gibson, R.I. & Millegan, P.S.; 1998

USE HIGHER RESOLUTION MAGNETIC DATA USE HIGHER RESOLUTION MAGNETIC DATA

MAGNETIC UTILIZATION

Regional depth to magnetic basementRegional tectonic analysisEuler deconvolutionCurie point analysis

Detailed basement interpretationDetailed fault and lineament analysisDelineation of volcanics, salt, and shale

Detailed, integrated 2D/3D modeling- faulting, basement structure, volcanic, salt edges, and sediment timing “Depth slicing” and lineament analysisSedimentary magnetic analysis

Detailed 2D / 3D modeling inversionIntegrated depth migration (pre- or postack) Magneto- startigraphy

None published

MAGNETICRESOLUTION REQUIRED *

20 km spacing5 – 8 km grid1 – 5 nTContinental grids, older surveys

2 – 5 km spacing1 - 2 km grid0.5 – 2 nTModern digital surveys, marine surveys, digitized older analog surveys

0.5 - 1 km spacing0.1 – 0.5 nTHigh-resolution, low- altitude surveys

0.25 – 0.5 km spacing0.1 – 0.5 nTHigh-resolution, low-altitude surveysBorehole magnetometer

* Typical required resolution; needs to be tailored to source depth and signal strength

20Modified from Gibson, R.I. & Millegan, P.S.; 1998

THE PARADIGM SHIFT IN GRAVITY DATA UTILIZATION THE PARADIGM SHIFT IN GRAVITY DATA UTILIZATION BY USING THEBY USING THE HIGHER RESOLUTION HIGHER RESOLUTION OF OF GRAVITY DATA GRAVITY DATA

GRAVITY UTILIZATION

Isostatic residual Regional tectonic analisisBasin and depocenter enhancementRegional modelingDigital data integration (with remote sensing, etc)

Semiregional structural / stratiigraphic modelingTarget-spesific enhancementsLayer stripping for improved delineation of exploration targetsSensitivity studies tied to density and lithology

Detailed, integrated 2D / 3D modeling (with seismic horizons, density, and velocity information)Porosity / pressure predictionSalt edge / base determinationEnhanced velocity analysis

Integrated 3D rock properties and velocity modelingIntegrated depth migration (pre-or poststack)Borehole gravity- remote porosity detectionDetection of shallow hazards

Integrated reservoir characterization

Borehole gravity

Time-lapse precision gravity , including for Carbon Storage Monitoring

GRAVITY RESOLUTION REQUIRED *

1 – 5 mGal2 – 20 km wavelengthContinental grids, satelite gravity, airborne gravity

0.2 – 1 mGal1 – 5 km wavelengthConventional marine and land surveys

0.1 – 0.5 mGal0.5 – 2 km wavelengthHigh-resolution land and marine surveys

0.1 – 0.5 mGal0.2 – 1 km wavelength0.01 – 0.005 mGal (borehole)High-resolution land, marine, and gradiometer surveys

0.02 – 0.1 mGal1 – 5 years

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