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SPE 20138

Reservoir Management: A Synergistic Approach&C. Thakur, Chevron U.S.A. Inc.SPE Member

Copyright t9S0, Socfefy of Petroleum Engineers Inc.

Thie paper waa prepared for presentatkn at the 1990PermianBaaln011and Gas RecoveryConferenceheldIn Midland,Taxae,March S-9, 1800.

Thla paper was selected for presentation by an SPE Program Committee followlng review of information contained in an abstract submitted by the author(e), Contents of the paper,as presented, havenotbeenreviewedbythe Societyof PetroleumEngineersand are aubjactto correctionby the author(a).The material,as presented,doesnotnacwwrily raflactanypositionoftheSocietyofPetroleumEnglnwr8,Itaoftkere,ormembers.Paperspresentedat SPEmeetingearesubjecttopublkationreviewbyEditorialCommttfeeaoftheSwletyofPetroleumEnglnaere.PermleaiontoWY faraafrktadtoanabstractofnotrmxethan300wwde.Wafrafknsmaynotbe@pied.Theabstractshouldcentaincawpkww ecWwWgmantof whereand by whomthe paperISprewntad.WritePublkationaManager,SpE, p.O- *X S3WS, Richardson,n 7--3333. Telex, 7309S9 SpEDAL.

ABSTRACT

Becauee of the complexities and varied areas of A team building approach, involving in-houeeexpertise Involved in making a primary, secondary, reservoir management forumslworkshope, has alaoor enhanced recovery prodect successful~ it has been employed. The main objectiveof the workshopsbecome necessary to adopt a team approach for has been to facilitate cotmmnication amongreservoir management. Until the early 1970s, engineering, geology, geophysics, and operationareservoir engineeringwas considered the only iteto staff. Synergetic recommendations for projectof technical importance in the management of a improvementhave been a mutual outgrowth of thesereservoir, However, after understandingthe value forums.of geology, this no longer holds true. Theeynergism provided by the interaction betweengeology and reservoir engineering haa been quite INTRODUCTIONsuccessful, but the reservoir management hasgenerally failed to recognize the value of other The first task of this paper is to definediectplines, e.g. production operations, drilling, reservoir management. The Webster dictionaryand differentengineeringfunctions. defines management as the judicious use of meana

to accomplish an end. Thus, the management ofThfs paper provides informationon the treatmentof reservoirs can be interpretedas the judicious usereservoir management as a SYSTBM. The System of various means available to a businessman inconsists of: 1) reservoir characterization, 2) order to maximize his benefits (profits) from acreation and operation of wells, 3) surface reservoir.processing of the fluids, and 4) fluids and theirbehavior in the reaervofr. These must be Most people consider reservoir managementconsidered aa interrelated parts of a unified synonymouswith reservoirengineering. As recentlysystem. as the early 1970s, reservoir engineering was

consideredthe only item of technicalimportanceinA reservoir management model involving the management of reservoirs. However, afterinterdleciplinaryfunctions is discttesedin this understanding the value of geoloEY, synergismpaper. Also, the success of this model in between geology and reservoir engineering hasdesigning and implementingthe North Ward Estes COZ become very popular and has proved to be quiteproject, Ward/Winkler County, Texas, is diecuseed beneficial.in detail. TMs reeervolrmanagement approach hasyialded a better deeign and installation of this Reservoir management has advanced through varioueC02 project. h addition, it has resulted in stages in the last 30 years. The technique aresuccessful workovers~ identificationof waterflood better, background knowledge of reservoirimprovements, and better plans for future C02 conditions hae iatprovecl,and automation usingprojecte. mafn~rame computers and personal computere has

helped data processing and management. Thedevelopmentaletages of reservoir management couldbe describedas:

Referencesand illustrationsat and of paper.

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Stage 1 - Before 1970, reservoir engineering 10 Creationand operation of wells.was considered the only item of technicalimportance in the management of reservoirs. 2 Surface processingof the fluid8.Wyllie, in 1962, emphasized two key items:(A) clear thinking utilizing fundamen;;; 3. Fluids and their behavior within thereservoir mechanics concepts ~ and reservoir.automation ueing basic computers. In 1965,Essley summarized What ts reeervoir The first two depend on tha third because the typeengineering? and concluded that in spite of of fluide (oil, gas, and water) and their behavioradvancement in technical aspects of reservoir in the reservoir will dictate where and how manyengineering,vital engineering2considerations wells to drill, and how they should ba produced andare often neglectedor ignored. proceesedto maximize profits.

Stage 2 - This covers the time period of the The goal is to maximize profits and thus neglecting1970s and 1980s. Craig et al (1977), and or de-emphasizing any of the items above couldHarrts and Hewitt (1977) explained the value jeopardizeour objective. For example,we coulddoof synergism between engineering and geology. well in studying the fluide and their tnteracttonCraig emphasized the value of detailed with rock, i.e. reservoir engineering,but if thereservoir description, utilizing geological, proper well andlor eurface ey8tem design is notgeophyeic~l and reservoir simulation considered,the recoveryof oil andlor gas will notconcepts. He challenged explorationists, be optimized. Mo8t people can cite exemplea ofwith the knowledge of geophysical tools, to mietakes made in our buaineas where we thoroughlyprovide a more accurate reservoir deszriptton studfed various aepects of the reservoir and madeto be used in engineering calculations. decieiona resulting in too many wells drtlled,Harrie and Hewitt presented a geologic improperapplicationof well completiontechnology,perspective of the synergism in reservoir inadequate surface facilities available for futuremanagement. Thay explained the reeervoir expansions,etc.inhomogeneity due to complex variations ofreservoir continuity, thickness patterns, and In this paper, the suggeeted reaervolr managementpore-space properties, e.g., porosity, approach involvee interaction between variouspermeabilityand capillarypressure. function8, as deecribed in Figure 1. Although not

shown, the approach emphasizes interactionbetweenAlthough the synargiem provided by the interaction various functton8 and their interaction withbetween geology and reservoir engineeringhas been management, economic, proration, and legal groups.quite successful, the reeervo%r management has This reeerwoir management model, involvinggenerally fatled to recognize the value of other interdisciplinary functione has provided ueefuldisciplines,e.g. production operations, drilling, reeults for several projects. A caee study ue%ngand differentengineeringfunctions. the North Ward Estes Field wtll be descr%bed to

illustratethis approach.The objective of raservoir management ia tooptfmizeprofitableoil and gaa recovery,which can The followingquestionand answer section describesbe obtainedby the followingsteps: our philosophyof reeervoirmanage$uent:

1. Identify and define all individual A) When should reservoirmanagementetart?reservoirs in a given field and theirphysical properties. The ideal time to start managing a reservoir

fS at its discovery. It is never too early to2. Deduce past and predict reservoir start this program, becauee early initiation

performance. of a coordinatedraservoir management program

3.not only provides a better monitoring and

Minimize drilling of unnecessary wells. evaluation tool, but also coste less in thelong run. For example, a few early l.)STacould

4. Define and modify (if neceseary)wellbore help decida if and where to set pipe. some-and surface systems. times these data can also provide the same

type of information normally available by5. Initiateoperatingcontrols at the proper complex and expensive cased hole, multiple

time. zone testing, An extra log or an additionalhour~s tine on a DST may provide better

6. Coneider all pertinenteconomic and legal information than could $e obtainad from morafactors. expeneivecore analyais.

Thus, the purpoee of reservoir management ie to Sometimes it is possible to do acme testsprovide facts, information,and knowledgeneceesary early on that can indicate the sdze of ato control operations and obtain the maximum raservoir. If it is of limited size, drillingposeible economic recovery from a reservoir. of unnaceesarywelle can be prevented.

Extending Calhoun8 idea, one can draw anRESERVOIRMANAGEMENTAPPROACH

~nagement,~tween esenoir and healthanalogy

It ie not efficient for theIn 1963, Calhoun described the engineering system reeervofr management tean to determine theof concern to the- petroleum engfnyr ae bein6 state of l reservoire health and than attemptcompoeed of three principalsubeystame ; to improve it. To be most effective, the tean

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E 020138 G. C. Thakur ,

must maintain the reservoirs and its sister (vi) Are additional data necessary?subsystemshealth from the start.

(vii) Has there been an adequateMost often reservoirmanagement fs not started geologicalstudy?early enough and the reservoir, wella~ andsurface systems are ignored for a long time. (viii) Has the reservoirbeen adequatelyMany times we considerreservotrmanagementat deftned?the time of a tertiary recovery operation.However, it is criticaland a prerequisitefor D) Why a Team Effort and How to Enhance It?an economically successful tertiary recoveryoperation to have a good reservofrmanagement Successful reservoir management requires anprogram already in place. Integrated group effort. All developmentand

operatingIn the Permian

dectsions should be made by theBasin, C02 flooding is reservoirmanagement team which recognizesthe

receiving more and more attention. An dependence of the entire system upon theefficientreservoirmanagementprogram for COZ nature and behavior of the reservofr.flooding (with a $2 per barrel injectantcost)

It isnot necessary that all decisions be made by a

is even more critical compared to reservoirengineer;in fact, a team member whowaterflooding (with a 5 - 10 cents per barrel considers the entire system, rather than justcost for water). Thus, it is very important the reservoiraspect, will be a more effectivethat all injected COZ be properly utilized in decision maker. It will help tremendouslyIfdisplacingoil to the productionwells. the person has background knowledge of

reservoirengineering,geology,productionandB) What, how and when to collect data? drilling engineering, well completion and

performance,and surface factltties. Not manyTo answer this question, we must follow an people in an organization have knowledge inintegrated approach of data collection all areas. However, many persons develop aninvolving all functions from the beginning. intuitive feel for the entire system and knowBefore collectingany data, we should ask the when to ask for technical advice regardingfollowingquestions various elements of the system.

(i) Are the data necessary and what The team effort in reservoirmanagement cannotare we going to do with these be emphasized too much. It is even moredata? necessary now than it has ever been before

because the current trend of the oil industry(ii) What are the benefits of these is not one of expansion.

data and how do we devise a planHost companiea are

carryingon their productionactivitieswith ato obtain the necessary data at staff much smaller than that existed just fivethe minimum cost? years ago,

Note that the reservoir management team must Also, with the advent of technology and theprepare a coordinated reservoir evaluation complex nature of different aubsyatems,it hprogram to show the need of the data difficult for anyone to become an expert inrequirement, along with their coats and all areas. Therefore, it is obvious that thebenefits. &nyx et al provides a detailed reduction of talent and increasingly complexreview of ~ta evaluation for reservoir technologiesmust be offset by an increase incalculations. quality, productivity, and emphasis on the

team effort.It must be emphasized that early definitionand evaluation of the reservoir system i~,~ A team approach to reservoirmanagementcan beprerequisite to good reservoir management. enhancedby the following:The team members must convince the managementto obtain necessary data to evaluate the (i) Facilitate communicationreservoir syetam and should participate in

amongvarious engineering disciplines,

operating decisions. geology and operation staff by:(a) meeting

What kinds of questions should we ask if weperiodically, (b)

c) interdisciplinary cooperation inwant to ensure the right answer in the process teaching each others functionalof resarvoir management? Example questions objectives,and (c) building trustare describedbelow: and mutual respect. Also, each

member of the team should learn to(i) What does the anawer mean? be a good teacher.

(ii) Doea the answer fit all he (ii) The engineer, to some degree, mustfacts; why or why not? develop the geologists knowledge

of rock characteristics and(iii) Are there other possible depositional environment, and a

interpretations of the data? geologistmust cultivateknowledgein wall completion and

Were the assumptions reasonable?other

(iv) engineeringtasks.

(v) -Arethe data-reliable? -.

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SYNERGISTICAPPRO.ACH SPE 02013

(iii) Each member should subordinatetheir ambitions and egos to thegoals of the reservoir managementteam.

(iv) Each team member must maintain ahigh level of technicalcompetence.

(v) The team members must work as awell-coordinatedbasketballteamrather than a relay team.Reservoir engineers should notwait on geologists to completetheir work and then start thereservoir engineering work.Rather, a constant interactionbetween the functions should takeplace. For example, it ia betterto knew early on if the isopachand cumulative oil/gaa productionmapa do not agree rather thanfinalizeall isopachmaps and thenfind that the cumulativeproduction maps are indicatinganother interpretation of thereservoir.

In summary, the synergism of the team approachcan yield a whole ia greater than sum of itsparts effect.

NORTH WARD ESTES FIELD - A CASE STUDY

Introduction

The Notth Ward Estea (NWE) field, located in Wardand Winkler Counties, Texas (Figure 2), wasdiscovered in 1929. It is an 18 mile x 4 mileanticlinorium. Cumulative oil production fronprimary and secondary recovery has been in excessof 320 million barrels, or about 25% OOIP, frommore than 3,000 wells. The field haa beenwaterflooded since 1955. Geologically,the fieldresides on the western edge of the Central BasinPlatform. The ~i.eld is part of an UpperGuadalupfan productive trend which extendsuninterrupted for 90 miles on the edge of theplatform (Figure3).

The average reservofrdepth is 2,600 feet; porosityand permeability average 19% and 19 md,respectively. The reservoir temperature ia 83F.The flood patterns are generally 20 acre five apotsand line drives.

Field Informationand Geology

The field was initially developed on 20-acrespacing. Later, however, the moat productivepartaof the field were drilled on a 10-acre spacing.Until the 1950s, the wells were mostly completedopen-holeand shot with nitroglycerine. Perforatedlfners were then hung from the casing, which wasset above the productive formation in the gaasands.

After 1950, the wells were completed caaed-hole,hydraulicallyfracturedand acid stimulated. Abouthalf of the current producers and injectors arecased-hola. Table 1 provldae additional

information on the field history, structure, andstratigraphy.

The producing formationsare Yatea and Queen sands,but most of the productionhas been from the Yatessands (Figure 3). They consist of veryfine-grainedsandatonesto siltstones,separatedbydense dolomite beds. These sands, as shown inFigure 4, are: A, BC, D, E, F, stray sands, Jl,J2 and J .3

Most of the BC was in the original gas cap andconsists of siltstone~ to finegrained sandstonewith clay. The D and E sanda are similar to BC.The atrsy is composed of thin bedded, lenticular,s-iltatonesand fine-grained sandstones,with highclays. The JI and J2 sands are composedof coareersanda with much less clay content and, therefore,have higher porosities and permesbilities.Generally, the J3 ia not well developed and is wetin most areas.

The Queen formation, which lies below the Yatessands, iS composed of intervals of fine-grainedsandstonea to siltstones, composed of numerousthin, lenticular sanda with poor lateralcontinuity. Thus, the Queen sand has beendifficult to waterflood.

ReservoirManagementTeam

A team includingall functionalgroups, as shown inFigure i, was fmmed to investigate all pertinentoptione for optimizing recovery from the field.The resulte of the team effort are describedbelow:

1. GeologicalCharacterization

A correlation scheme was developed forthe field based upon laterallycontinuous

.key dolomites that bracket the productivesanda and segment the reservoir intodiscrete mappable units. A computerdatabase wae built by our geologists tofacilitateche processingand integrationof large volumes of data to aid in thegeological characterization study. Thedatabase componentswere:

A.

B.

c.

D.

E.

Wireline log data from 3,300wells, which included about 15million curve feet.

Core data consisting of 538cores, which totaled about30,000 feet of analysee andlithologydescription.

Marker data for more than60,000 correlation markers.

Fluid contact data, i.e.original gaa-oil and oil-water.

Production data, consisting ofhistorical and wellbore data,includingdiagrams.

Core analyseswere depth covrected. Logewere normalized using a 30-feet intervalof laterally continuous anhydriticdolomite. -Gore porosity data were

442

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fi. fi,.o c r. Thnkllv 5c! u4vJ.aO v.-. . . . . . . . .

cross-plotted versus bulk density log (A) No reduction in injectionrates

derivatio;of ~%Xcy!~ans$=cti%values was observed during or after

C02 injection.for hole rugostty, overburden pressure,and lithologiccomplicationswere ~~plied (B) The C02 injection rate wasto refine the porosity transform. The about 20Z higher than the waterfinaltransformsare shown in Figure 5. injectionrate.

As eeen in this figure, the correlation (C) No significant change inbetween porosity and permeability ia injection profile was observedpoor. However, when the correlation during or after C02 injection.baaed upon lithofacies was+ made, goo$correlation coefficientswere obtained. In addition to the above-mentionedStructure and porosity-feet maps were results, the co* injectivity testmerged with fluid contact and water implanted a valuable seed of team~aturationdata to calculatevolumetric. effort that led to fruitful resultsF>cies relationships and actual to during the design and implementationofapparent pay ratios were applied to the C02 project.determine effective hydrocarbon porevolume. Computer generated net ieopach 3. C02 Project Design and Implementationmaps of the sands display a north-southstrike. The sands pinch out into an The C02 flood design was based upon aevaporite facies updfp and a carbonate history match of the waterfloodfacies downdip. performance of the SIX section project

area, the selection of typical patternsReference 12 describesthe details of the including a detailedstudy.

reservoirAbout 11 man years and $1.6 characterization, a prediction for

million were spent to achieve the above continuation of the waterflood,results. Figure 6 summarizes predictions for C02 flooding, and thecomputer-aided characterization studysteps. Normalized log and core data, ::l:n::reofp,:yec::rya:l?re:;::;::to:markers, fluid contacts, and production were made for continuation of thedata were quality checked and corrected waterflood and for C02 floodfng.for any errors. The output includedmaps Additional reservoir simulation was(structure, isopach and conducted to determine the optimum C02porosity-thickness), porosity va. slug size.permeabilityplots, water saturationandvolumetric data, production plots, and The anticipated increase in oil recoverycross-sections, including wellbore from the six section, Stage 1 areadtagrams. (containing 165 producing wells and 192

injection wells) as a result of COZAn example of a sand trend cross-section flooding is 16.5 million bbl of oil.is shown iu Figure 7. It is based upon Stages 2 and 3, tentativelyecheduledforbasic geologic data and supported by 1993 and 1995, will depend upon theproductiondata. success of the firat stage and on oil

price.One of the outcomes of thecharacterization study has been Management approval of this project wasidentification of well workovers. In obtained in December 1987. In Januaryaddition, several waterflood projects 1988, a task force was formed, and thewere designed and implemented. A C02 injection was initiated in Marchwaterflood project that did not prove as 1989. Currently, about 55 MMCF/D of C02successful as others was later analyzed and hydrocarbon gas is being injected.in terms of the characterizationstudy. To date, project response has beenIf the project had been consideredafterthe study, it probably would not have

encouraging, with the actual production

been implementedand considerablesavingsmeeting or exceedingthe forecast.

could have been attaiaed. The C02 plant compressed, desulfurizea,and dehydrates all COa-rich gas produced

2. C02 InjectivityTest from the project. The plant is designedto process 65 MMCF/D of producedgas. In

A C02 injectivity test was conducted to addition to reinfection gas, the plant~ investigate any injectivity reductions

during COZ and water injection cyclee.will also produce four (4) tons per dayof marketable sulfur from moderate

An injector in good mechanical condition concentrations of H2S (2%) in theand with no hydraulic fracturing was hydrocarbongas.selected. Geological cross-sectionsthrough thie well showed well-developedsande. The injectivity test providedvalu8ble information,as describedbelow:

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R!7.CF!RVOTRMiiNfiCE!MF!tJT- A SYNERGISmrn nnnnnnu cm nml 2.= --------- . .- .....--..- .. _-.. ..-_aA J.- Cwr=mrak.h ..4 c. -...

Team Effort 2. Discuss typical reservoirmanagement schemes,strengthening efforts to

1. Why a Team Effort?increase

productionlreservesand minimize costs.

The North Ward Estes Field is one of the 3. Discuss management strategy forlargest fields for Chevron U.S.A. Inc. and it

specificfields,

has significant EOR potential.providing an opportunity for an

C02 flooding exchange of ideas between varioua work groups.was the only economic option available torecover significantreserves from this field. 4. Concentrateon problem araas for these ZIeldeFor about 1,300 producing wells, the+average and recommend an action plan, reeulting fromproduction rate is only 7 BOPD at 95 Z water the collective contribution of allcut. Out of the 1,300wells, about 700 make 5 participance.BOPD or less. Also, 300 wells are now capableof producing only at or below the presenteconomic limit, Thus, if COZ floodingwas not

(Note that SPE offered a forum in August 1989on Reservoir Management; however, our format

implemented right away, economics would have is much differentthan SPES.)dictated plugging and abandoningof uneconomicwells. BenefitsReceived

Keeping the above pointa in mind and As a result of the in-house forums, theconsidering the average age of wells in thefield of about 35 years~ a window of

participantsachieved the following:

opportunity became quite obvious. If the 1. Refocused the minds of the participants onwells were abandoned,it was unlikely that the reservoirmanagement.project would have been undertaken becauseeconomics would not have justified re-drills. 2. Shared knowledge, experiences, judgments andThus, it became an urgency to start an EOR ideas.project, i.e. either move quickly or risklosing the chance. To design and implementan 3,EOR project and to Improve the performanceof

Questioned and commented on new contributions

the existing waterfloods, a study team, asand extractedvaluable ideas.

shown in Figure 1 was formed. 4. Generated ideaa and prepared plans involving

2. What Did the Team Achieve?all team members.

5. Developed an understanding of the collectiveDuring the design phase, as many as 25 to 30 aim of the team and the way in which anmembers of varioas functional groups worked

comprehensive design of aindividual, along with the rest of the team,

together on a can contribute.six-sectionCOZ project, reviewad hundreda ofworkover candidates~ and evaluated several Design of In-house Forumswaterfloodmodificationprojects.

In addition to initiating many workovers andAbout 30 participant attend each forum. Theparticipance include 6-8 reservoir engineers, 6-8

waterflood modification projects~ within 15 production engineers, 6-8 geologiata andmonths C02 injection wae started in the geophysicists, 2-3 design andsix-section project Within a

constructionarea. engineers, 2-3 gaa and chemical engineers, 1-2

year-and-a-half,the gas processing plant was drilling engineers,built and started. The teams goal for every

and 3-5 field foremen andproductionauperintendents(ace Table 2).

aspect of the project, from well workovers,reservoir studies,C02 injectionand gathertng Typically, the forums are held for two (2) days andsystem construction to atart up was 2 to 3 field caae etudies ara diacuesed. Theaccomplished in a short time without studies are selected by the production divieionsacrificingquality. staff and are of critical importance to the

division. The division managers concurrence onIn eummary, the teamwork across the functionlines has resulted in successful design and

the caae studies is obtainedbeforehand.

implementationof many successful projects in The forum starta with a presentation by thethe North Ward Estes Field. Division Manager. He conveys hie philosophy of

reservoir management. We have observed this to be

ROLE OF RESERVOIRMANAGEMENTFORUM/WORKSHOPone of the most productivesession.ebecause:

Objective1. It provides an informal interaction between

the reservoir management teem members and

We have conductedmanagement.

several in-house reservoirmanagement workshope. The objectives of the 2. The participance obtain an tnatghtinto theworkshops have been to: workinge of the local management. They get a

feel of what may or may not be po.saible to1, Focus attentton on practical aepects of be approved. (Most participance indicated

reservoirmanagement. that it provided them with a real opportunityto understand the local management and

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PE 020138 G. C. Thakur

minimized any frustrationsthat might arise as INPROVINGSUCCESS IN IMPLEMENTATIONa result of disapprovalof a project.)

Table 6 describes a step-by-stepprocedure on howThe manager essentiallysets the tone of the forum. to improve success in implementing a reservoirHis convictionand commitmentgenerallyprovides an managementprogram.enthuefasm for all participants.

1. The first step involves starting with a planThe subsequent sessions are described in Table 3. of action, including all functions. It iSA general discussion on these topics is presented common for many reservoir management effortsby knowledgeable staffs. An outline of the to devise a plan, but this plan usually doeadiscussion on the role of geology in reservoir not involve all functionalgroups. Thus, notmanagement is described in Table 4. all groupa buy into these programs, and the

cooperationbetween var%ous functions is belowAfter completing the general discussion, case the desired level. If a plan is to bestudies are presented by the participants. These developed and implementedin the best way, itparticipants are directly involved with the cases must have commitment from all disciplines,in their daily work, and their pressntattons includingmanagement.include prepared written outlines of the varioustopics listed in Table 5. About 6-8 people mske 2. The plan must be flexible. Even if thepresentationson a caae study and cover all aspecte reservoir management team members prepareof a project, including economic, legal, and plana by involving all functional groups, itenvironmentalconcerns. does not guarantee success if it is not

adaptable to surroundingcircumstances (e.g.,After the presentationof the case bcudy, the large economic, legal, and environmental).group is broken into four (4) teams. Each teamconsists of about 2 raservoir engineers, 2 3. The plan must have management support. Noproduction engineers, 2 geologistelgeophysicists~ matter how good the plan Is in technicaland 2 design and construction engfneerslgaa and terms, it must have local and higher levelchemical engineersfdrillingengineerslfieldforemen management blessings. Without their support,(see Table 2). A balance in terms of familiarity it would not have a chance to get approved.with the case study between the team members fs Thus, it is necessary that we get themade. In addition, each team possesses a good managementinvolved from day one.technical background in various aspects ofreservoirmanagement. 4. No reservoir management plan can be

implemented properly without the support ofThe team members work in separate rooms and perform the field personnel. Time and time again wethe followingin a problem solving style: have seen reservoir management plans fail

because either they are imposed on field1. Define the probleme. personnel without much explanations or they

are preparadwihtout their involvement. Thus ,2. Discuss various solutions (including the field personnel do not have a commitment

alternatives)for each problem. to these plans.

3. List the pros and cons for each solution. 5. It ia critical to have periodic revfew

4* Prepare and recommend solutione, consideringmeetings, involving all team members. Most,

economic aspects.ff not all, of these meetings should be heldin the field offices. The success of these

Each teatiis guided by a coordinator/facilitatortomeeting will depend upon the abflity of each

member to teach hislher functionalensure that it ie making progress and steered in

team

the right direction.objectives.

Next, all teame gather in a large conference room CONCLUSIONSand make preaentatione on their findings one byone. When a team makes its preeentation,members 1.of the other teame are encouraged to ask questions

A model involving interdisciplinaryfunctions

and provida comments. Any new ideas generated are has been shown to be effective in designing

discussed and noted.and implementing a successful reservoirmanagementprogram.

At the conclusion of all presentations,ideas arerecorded and displayed. A general discussion

2. This model has resulted in a better design and

involvin8 teem members starts and concludee with ainstallation of a COZ project in the North

list of specific recommendatlona on the case study.Ward Estea field. In addition, it haa yieldedaucceaeful workovers, waterflood improvements,

The bottom line of the forums is to generata ideasand better planning for future COZ projacta.

and prepare plane (short-term and long-te~) ~,involving all team members.

In-house workshopa or forums proved successfulin the teem building aspect of reservoirmanagement. Theee forums facilitatedcommunication among engineering, geology andgeophy.e%cei, and operations staff, and resulted

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RFSERVOIRMANAGEMENT-

in combined recommendations for projectimprovement,

ACKNOWLEDGMENTS

The author expresses his appreciation to themanagementof Chevron U.S.A. Inc. for permission topublish this paper. The content of the paper isprfmarily derived from the in-house ReservoirManagement forums and workshops coordinatedby theauthor. The work performedby the participantsofthese forums (from geology and geophysics, allengineering functions, drilling, and productionoperations)ie highly appreciated.

REFERENCES

1. Wyllie, M.R.J.: Reservoir Mechanics -Stylized Myth or Potential Science?,J. Pet.Tech. (June 1962), pp. 583-588

2. Esaley, P.L.: What is ReservoirEngineering?,J. Pet. Tech. (January 1965),pp. 19-25

3. Craig, F.F. et al: Optimized RecoveryThrough Continuing InterdtaciplinaryCooperation, J. Pet. Tech. (July), PP.755-760

4, Harris, D.G. and Hewitt, C.H.: Synergism inReservoir Management - The GeologicPerspective, J. Pet. Tech. (July 1977) pp.761-770

5. Calhoun, J.C.: A Definition of PetroleumEngineering,J. Pet. Tech. (July 1963)

6.

7.

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13.

Amyx, Bass and Whiting: PetroleumReservoirEngineering, McGraw-Hill Book Company, NewYork (1960)

Goolsby, J.L.: The Relation of Geology toFluid Injection jn Permian CarbonateReservoirs in West Texas, S*W. Pet. ShortCourse - Lubbock, Tx, 1965

Jordan, J.K.: Reliable Interpretation ofWaterflood Production Data, J. Pet. Tech.(August 1955),PP. 18-24

Weber, K.J.: Influenceof Common SedimentaryStructureson Fluid Flow in ReservoirModels,J. pet. Tech. (March 1982), PP. 665-672

Havlena, D.: Interpretation,Averaging andUse of the Basic Geololgfcal - EngineeringData, J. Canadian Pet. Tech., part 1s V+ 5SNo. 4 (October- December 1966), pp. 153-164;part 2, V, 7, No. 3 (July - September 1968),pp. 128-144

Harris, D.G.: The Role of Geology inReservoir Simulation Studies, J. Pet. Tech.(May 1975),pp. 625-632

Stanley, R. G. et al: North Ward EstesGeological Characterization,to be publishedin 1990 AAPG Bulletin.

Winzinger, R.~ et al: Design of a Major C02Flood - North Ward Estes Field, Ward County,Te~asl,SPE paper t?o. 19654, presented at theSPE Annual TechnicalConference,October 8-11)1989, San Antonio, Texaa

TABLE 1

North Ward Estoo Mold

l 1929-NORTH WRD FIELD DISCOVERED9.W, OBRIEN #4 SECTION 19

l 19S6-E8TE8 FIELD DISCOVEREDE.W. ESTES #1 SECTION 98

. $944-FIELDS COMBINEDl 1956-WTER FLOOD BEQANl t12al- POLYMER PROJECTS BEGANl &CCO + WELLS DRILLEDl ACTIVE WELL8-1,901 PRODUCERS, 962 INJECTORS

(6/1/87) 10 ACRE SPAGINa

. LOW RELIEF ANTIFORMl CENTRAL BASIN PLATFORM HOMOCLINE

l About 90 pOOp@l 6-ORE*

6-OPE6-8 Q&Q2-s Qbc2 -aDac1-2 Drtlllng

TABLE 2In-houao Forums on Prac+tioal Aepocts

of Reservoir Management

9-6 Flold Poroonnel.

20 - 37

G8efoot 2- s Fhfda(Caoo studfes)

l Proswrtatlon by Dlvlsfon Mmmeer

l *rrorsl prosontstlon/(Outllno + handouts) /

l Break into 4 oroupe 2 RE, 2 Pi% 2 Q&Q2(QOC, DAC,Drllllno & Field)

l Small group dlccusalonsl LWO. group dioousslorrsl 8Poelf10 rooommwrdatlons

- short-form- Iwiff-torrrr(Co9t-borrofit wralyols)

I l PRIMARY PRODUCTION-YATES ,n= . la. ..... E.,..,,. Dc. D,,.,l,,,lm=.l.., !. nln . n.n,.. a famoh,lc.#NERAGE DEPTH-2600

..- ... . . . ,.. . . ... .... . . .... . - .-.....,, . ... .... . . .... . -. --- .-., - --- ...,..--,

,,. - - -. . ,.. --,-., c--, marine,D&O - DemlQn 8 @n.tru@lon Engtneerlrq.

I SECONDARY PRODUCTION-QUEEN= - .. . I!. rni..l =r!!!

AVERAQE DEPTH-S1OO. AQE-PERMIAN (LATE QUADALUPIAN). . .-. ..l L17HOLO@Y-VERY FINE QRAIN BAND AND SILT-

BTONEt3,DOLOMlTE/ANHYDRITE INTERBEDDEDl AVERAQE POROSITY-19%l AVERAaE PERMEABILITY-19 md,l ENVIRONMENT-TIDAL FLAT

l

l

l

l

l

a

TABLE 3

Forum DiscussionINTRODUCTION

DATA REQUIREMENTS

Outline

ROCK AND FLUID SAMPLING AND ANALYSIS

ROLE OF GEOLOGY

BACKGROUND MATERIALS ON PRACTICALASPECTS OF RESERVOIR MANAGEMENT

CASE STUDIES

TABLE 5

Case Study CWltne

l OVERVIEW OF FIELD QEOLOQY & PERFORMANCE

l RESERVOIR ENQINEERINQ WORK

l PRODUCTION 4 INJECTION WELLS

l SURFACE FACILITIES

l INJECTION WTER QUALITY

l CORROBION & SCALE

l PRODUCTION OPERATIONS

c DRILLIN@ OPERATIONS

l CASE 8TUDY REVIEW * DIBCUBBION IN- SMALL WtOLfPB- LAR@E WOtJP

l BPEGIFIO RE06MMEf4MT10NS

TABLE II

Role of tiO1ORY in RetIew.lr llan.gemenc

l DEPOSITIONAL ENVIRONMENT

l CROSS-SECTIONS & FENCE DIAGRAMS

l HCPV DETERMINATION

l RESERVOIR PETROLOQY

l ORGANIC GEOCHEMISTRY

l USE OF OLD WELL RECORDS & OABLE TOOLINFORMATION

l

s

l

l

l

9

l

441

DETERMINATION OF FLUID CONTACTS

FORMATIQN WTER

TABLE 6

HOW to Improve Success in Implementtns aResew.ir Management Program?

START WITH A PLAN OF ACTION,INVOLVINQ ALL FUNCTIONS

FLEXIBLE PLAN

MANAGEMENT SUPPORT

COMMITMENT OF FIELD PERSONNEL

PERIODIC REVIEW MEETINGS, INVOLVINQ ALLYEW idEMk3ERf3ONTERDlWIPLINARy000PERATfON IN TEAOf+lNG EAOH OTHERSFUNCTIONAL OBJECTIVES)

\\\

FIs, 1 - RcsorvolrMmcgeuwnt Approach

h \ w /w--Kl

u

,. sf% 20138

\\\ kA n.., .L..m...*..*.* ..........~ F. ----- . . . . . . .. . . .

L\\\\\U, vs[ v~ =---

F e$&aO#cs*nlwO ,,*. L----. .,**$*/4 %O, fc. wo ,,**,0*.*$~ **O**,Ems- *L,*.* l,,,,,. ,@.c**,,*$** A y----+\ IFig. 3 - North Ward Ester CeOlO@C HOrizOn*

GR RHO-B

G.W.O. + 1087 TANSILL

A SAND

PC SAND

D SAND

STRAY SANDS

J 1 SAND

TOP/SEVEN WE RS s Ao

s

Fig, 4 - Type LOS for North Ward Estee Field

SL

-4.000

-8.000

-12,000

.SPE 20138

. . .- -. :. :-,- --------+ +,.. .

F . .,.. ..

\ \l

%%-,, l;! l

.*.,

d \I------* . l1- 1. .. .--.l::. L-

!

.

Ammviwwd

.

I

Oilz!

450

IFIE. 6 - xorth wd EstwCawut=r-A~dedCharacteri2ati0nStudy

*.

TYPE LOGXLYw!

SPE 20138

==%

TISEVE

BI&+B

\ k===-JFig. 7 - SandTrends for North Hard Ewes Field

SPE Paper Numbers 20139Thru20147

No C~pies GWailmble

NO papers assigned to These Numbers