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INTEGRATED RESERVOIR CHARACTERIZATION

Overview

The ultimate goal of any exploration and production (EampP) e ort is to

increase hydrocarbon reserves while ensuring their e cient and economicalrecovery aining detailed nowledge of reservoir geometry roc propertiesand productive capacity is the $rst step toward reservoir optimiation

ntegrated reservoir characteriation combines all geological geophysicaland engineering data pertinent to understanding uid ow and reservoirbehavior and uses the data to produce a earth model that can be used inall phases of $eld development n this way it di ers from traditionalreservoir characteriation pro+ects which tend to focus on geologic andengineering analysis of proposed enhanced recovery pro+ects as well asdrilling production engineering and reservoir simulation

eologic data comes from well logs roc samples outcrops maps crosssections stratigraphic studies structural studies geochemical studies andpetrophysical studies

eophysical information may include gravity data magnetic data andseismic data as well as other types of data eismic data in particularencompasses a wide spectrum of information from - or surveysplus vertical seismic pro$le (P) studies crosswell information and seismicattribute analysis

Engineering data includes petrophysical well test production0in+ectionpressure and uid analysis information as well as any relevant stress $eldand fracture data

These data can be integrated to overcome the limitations inherent in anysingle data domain 1or example seismic data can sample a large arealextent of a particular reservoir but it provides only limited verticalresolution 2ore data on the other hand provides extremely $ne verticalresolution but samples only a minute portion of total reservoir volume3owever correlating speci$c seismic attributes to important coreproperties (porosity for example) combines the advantages and minimies

the disadvantages of both data types

ntegrated reservoir characteriation is generally an interdisciplinaryinteractive team e ort 4 team is usually divided into three main disciplines5eology eophysics and Engineering uccessful interaction among thesedisciplines generally involves two approaches5

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n the $rst approach team members from each discipline integrate allpertinent data and construct preliminary models The team members thencompare models with the others and re$ne then integrate with modelsproduced by the other disciplines

The second approach integrates all data from an early stage and continuallyupdates and re$nes the result as more analyses are performed and moreinformation is accumulated

These two approaches are each appropriate under di erent circumstances6here very little initial information exists it may be easier to construct anintegrated model early and then progressively update it as new data areac7uired 1or a $eld in which large amounts of data are available developingdisciplinespeci$c models as a $rst stage e ort may be the only practicalway to ensure that all relevant information is included

ntegrated reservoir characteriation results in a threedimensionaldescription of a complex heterogeneous volume of roc in the subsurface8o matter how concise and numerically constrained the $nal model may beit will always be an approximation of the reservior There are never enoughdata to fully represent the details of reservoir structure and internalarchitecture9 the precise lateral and vertical distribution of roc and uidproperties9 or the exact con$guration of uid pathways barriers andcontacts

Integrated reservoir characterization prod ces an integrated earthode soeties

caed a shared earthmodel $ that is designed todescribe the static anddynamic factors that a ectuid ow (eamer et al ltlt=) uch a model isproperly viewed as a worin progress open toimprovement at any stageof its development 4critical test of any model is

to drill new wells or launchnew (e g enhanced)recovery programs This inturn yields new data thatreveal weanesses in theexisting reservoirdescription The new datacan be then incorporated to re$ne the model

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4t an early stage the shared earth model should be accurate enough tosupport a preliminary $eld development and management plan reduce thenumber of appraisal wells needed optimie their locations and determine

speci$c data re7uirements The re$ned model incorporating these datashould then be su cient to guide the actual drilling or recompletion programduring the main phase of development ata from the development phase of activity will in turn be used to further re$ne the model so that duringsubse7uent stages of production decline the unswept portions of thereservoir can be identi$ed and the accuracy of reservoir simulation can beenhanced

4dvances in software technology have greatly aided the process of buildingand updating shared earth models uch advances mae it possible tointegrate geologic geophysical and engineering data in three dimensions at

individual worstations ( 1igure - 5 Complex

ig re amp

interdisciplinary modeling of reservoir intervals was able to show the three-dimensional distribution of sands having temperatures above a certainspeci ed limit re ecting the in uence of continued steam ooding 9 inger etal ltltgt) This development has helped to decrease the sie of reservoircharacteriation teams while greatly improving their e ciency 2ommercial

modeling software pacages commonly employ well log and seismicinformation as base data which various mapping algorithms and

8192019 Integrated Reservoir Characterization1

httpslidepdfcomreaderfullintegrated-reservoir-characterization1 25

n the $rst approach team members from each discipline integrate allpertinent data and construct preliminary models The team members thencompare models with the others and re$ne then integrate with modelsproduced by the other disciplines

The second approach integrates all data from an early stage and continuallyupdates and re$nes the result as more analyses are performed and moreinformation is accumulated

These two approaches are each appropriate under di erent circumstances6here very little initial information exists it may be easier to construct anintegrated model early and then progressively update it as new data areac7uired 1or a $eld in which large amounts of data are available developingdisciplinespeci$c models as a $rst stage e ort may be the only practicalway to ensure that all relevant information is included

ntegrated reservoir characteriation results in a threedimensionaldescription of a complex heterogeneous volume of roc in the subsurface8o matter how concise and numerically constrained the $nal model may beit will always be an approximation of the reservior There are never enoughdata to fully represent the details of reservoir structure and internalarchitecture9 the precise lateral and vertical distribution of roc and uidproperties9 or the exact con$guration of uid pathways barriers andcontacts

Integrated reservoir characterization prod ces an integrated earthode soeties

caed a shared earthmodel $ that is designed todescribe the static anddynamic factors that a ectuid ow (eamer et al ltlt=) uch a model isproperly viewed as a worin progress open toimprovement at any stageof its development 4critical test of any model is

to drill new wells or launchnew (e g enhanced)recovery programs This inturn yields new data thatreveal weanesses in theexisting reservoirdescription The new datacan be then incorporated to re$ne the model

8192019 Integrated Reservoir Characterization1

httpslidepdfcomreaderfullintegrated-reservoir-characterization1 35

4t an early stage the shared earth model should be accurate enough tosupport a preliminary $eld development and management plan reduce thenumber of appraisal wells needed optimie their locations and determine

speci$c data re7uirements The re$ned model incorporating these datashould then be su cient to guide the actual drilling or recompletion programduring the main phase of development ata from the development phase of activity will in turn be used to further re$ne the model so that duringsubse7uent stages of production decline the unswept portions of thereservoir can be identi$ed and the accuracy of reservoir simulation can beenhanced

4dvances in software technology have greatly aided the process of buildingand updating shared earth models uch advances mae it possible tointegrate geologic geophysical and engineering data in three dimensions at

individual worstations ( 1igure - 5 Complex

ig re amp

interdisciplinary modeling of reservoir intervals was able to show the three-dimensional distribution of sands having temperatures above a certainspeci ed limit re ecting the in uence of continued steam ooding 9 inger etal ltltgt) This development has helped to decrease the sie of reservoircharacteriation teams while greatly improving their e ciency 2ommercial

modeling software pacages commonly employ well log and seismicinformation as base data which various mapping algorithms and

8192019 Integrated Reservoir Characterization1

httpslidepdfcomreaderfullintegrated-reservoir-characterization1 35

4t an early stage the shared earth model should be accurate enough tosupport a preliminary $eld development and management plan reduce thenumber of appraisal wells needed optimie their locations and determine

speci$c data re7uirements The re$ned model incorporating these datashould then be su cient to guide the actual drilling or recompletion programduring the main phase of development ata from the development phase of activity will in turn be used to further re$ne the model so that duringsubse7uent stages of production decline the unswept portions of thereservoir can be identi$ed and the accuracy of reservoir simulation can beenhanced

4dvances in software technology have greatly aided the process of buildingand updating shared earth models uch advances mae it possible tointegrate geologic geophysical and engineering data in three dimensions at

individual worstations ( 1igure - 5 Complex

ig re amp

interdisciplinary modeling of reservoir intervals was able to show the three-dimensional distribution of sands having temperatures above a certainspeci ed limit re ecting the in uence of continued steam ooding 9 inger etal ltltgt) This development has helped to decrease the sie of reservoircharacteriation teams while greatly improving their e ciency 2ommercial

modeling software pacages commonly employ well log and seismicinformation as base data which various mapping algorithms and

8192019 Integrated Reservoir Characterization1

httpslidepdfcomreaderfullintegrated-reservoir-characterization1 45

geostatistical procedures render into representations of reservoir geometrystratigraphy structure and roc property distribution

eostatistics has come to play an increasingly important role in estimatingreservoir property values at unsampled locations ( 1igure 5 Geostatistical

porosity cross section through a carbonate mound reservoir based on a 15-layer model 9 data courtesy Tom 2hidsey r )

ig re

ore sophisticated capabilities for seismic data processing and A7uic looAreservoir simulation enable models to be built tested and re$ned on anongoing almost daily basis Besearch into these and other capabilities willinevitably open new improvements for onscreen digital reservoircharacteriation

mproved software modeling with the capability to rapidly synthesievast amounts of diverse data plays an important role in the future of integrated reservoir characteriation (Cland et al ltltD9 eardsell et al ltlt=) 4t the same time however digital modeling no matter howsophisticated cannot reproduce the subsurface exactly 4dvances incomputer technology have not eliminated the central role of the interpreterany uncertainties exist in every case of data visualiation because of

8192019 Integrated Reservoir Characterization1

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fre7uent instances involving limited seismic marers core data well logcoverage or well test information n the end integrated reservoircharacteriation means creating the most accurate useful earth model withthe data available at any particular stage of $eld development