Reservoir Model Design: A Practitioner's Guide PDF
Preview Reservoir Model Design: A Practitioner's Guide
Philip Ringrose Mark Bentley Reservoir Model Design A Practitioner’s Guide Second Edition Reservoir Model Design (cid:129) Philip Ringrose Mark Bentley Reservoir Model Design ’ A Practitioner s Guide Second Edition PhilipRingrose MarkBentley EquinorASA TRACSInternationalLimited NorwegianUniversityofScience Heriot-WattUniversity andTechnology AberdeenandEdinburgh Trondheim,Norway Scotland,UK ISBN978-3-030-70162-8 ISBN978-3-030-70163-5 (eBook) https://doi.org/10.1007/978-3-030-70163-5 #SpringerNatureSwitzerlandAG2015,2021 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeor part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations,recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway, andtransmissionorinformationstorageandretrieval,electronicadaptation,computersoftware,or bysimilarordissimilarmethodologynowknownorhereafterdeveloped. Theuseofgeneraldescriptivenames,registerednames,trademarks,servicemarks,etc.inthis publication does not imply, even in the absence of a specific statement, that such names are exemptfromtherelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. Thepublisher,theauthors,andtheeditorsaresafetoassumethattheadviceandinformationin thisbookarebelievedtobetrueandaccurateatthedateofpublication.Neitherthepublishernor the authors or the editors give a warranty, expressed or implied, with respect to the material containedhereinorforanyerrorsoromissionsthatmayhavebeenmade.Thepublisherremains neutralwithregardtojurisdictionalclaimsinpublishedmapsandinstitutionalaffiliations. Cover figure: Multiscale geological bodies and associated erosion, Lower Antelope Canyon, Arizona, USA. Photograph by Jonas Bruneau. # EAGE reproduced with permission of the EuropeanAssociationofGeoscientistsandEngineers. ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSwitzerlandAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland Preface Thisbookisaboutthedesignandconstructionofsubsurfacereservoirmodels. Intheearlydaysoftheoilindustry,oilandgasproductionwasessentiallyan engineeringactivity,dominatedbydisciplinesrelatedtochemicalandmechan- ical engineering. Three-dimensional (3D) geological reservoir modelling was non-existent, and petroleum geologists were mostly concerned with the inter- pretation of wire-line well logs and with the correlation of geological units between wells. Two important technological developments – computing and seismicimaging–stimulatedthegrowthofreservoirmodelling,withcomputa- tionalmethodsbeingappliedtomapping,volumetricsandreservoirsimulation. Geological or ‘static’ reservoir modelling was given further impetus from the development of geostatistical techniques, allowing the reservoir modeller to estimate inter-well reservoir properties and hence make statistical predictions. 3Dreservoirmodellinghasnowbecomethenorm. Reservoirmodelsinthemselvesdonotgenerateprospectsordevelopment scenarios, increase productivity or reduce risk and uncertainty. They are simply tools which reflect our ability to achieve these goals. Advances in reservoir modelling cannot therefore be compared to technology breakthroughs such as 4D seismic imaging, horizontal drilling or EOR methods. Reservoir modeling tools are, however, invaluable tools for integratingknowledgeandformakingstrategicdecisions. Astheworldmovesintotheenergytransitionandoilandgasproductionis likely to decline, energy and transportation will be increasingly powered by renewable or low-emissions technologies. In this new era, CO disposal and 2 subsurfaceenergystoragewillbecomeincreasinglyimportantandwillmake new demands of subsurface modelling. The fluids used and stored in the subsurface may change but the value of porous rock reservoirs will remain. Wewillneverceasetoneedtoknowhowthesefluidsmoveinthesubsurface, and modelling of subsurface reservoirs will remain a tool for building this understandingandmakingusefulforecasts. *** The explosion of reservoir modelling software packages and associated geostatistical methods has created high expectations but also led to periodic disappointments.Thishasgivenbirthtoanoftquotedmantra“allmodelsare wrong.” v vi Preface This bookemerged from a series of industry andacademic coursesgiven bytheauthorsandaimedatguidingthereservoirmodellerthroughthepitfalls andbenefitsofreservoirmodelling,inthesearchforareservoirmodeldesign that is useful for forecasting. Reservoir modelling and simulation software packagesoftencomewithguidanceaboutwhichbuttonstopressandmenus touseforeachoperation,butlessadviceontheobjectivesandlimitationsof the model algorithms. The result is that whereas much time is devoted to modelbuilding,theoutcomesofthemodelsoftenfallshortoftheirobjectives. Ourcentralcontentioninthisbookisthatproblemswithreservoirmodelling tendnottostemfromhardwarelimitationsorlackofsoftwareskillsbutfromthe approach taken to the modelling – the model design. It is essential to think throughthedesignandtobuildfit-for-purposemodelsthatmeettherequirements oftheintendeduse.Allmodelsarenotwrong,butinmanycasesmodelsareused toanswerquestionswhichtheyweresimplynotdesignedtoanswer. Wecannothopetocoverallthepossiblemodeldesignsandapproaches,and wehaveavoidedasmuchaspossiblereferencetospecificsoftwaremodelling packages.Ouraimistoshareourexperienceandpresentagenericapproachto reservoir model design. Our design approach is geologically based – partly because ofour inherentbiasasgeoscientists – but mainlybecause subsurface reservoirsarecomposedofrocks.Theporespacewhichhousesthe‘blackgold’ ofthe oil age,the ‘goldenage’ ofgas orthefluidsdisposedandstoredinthe new‘ageofsustainability’,hasbeenconstructedbygeologicalprocesses–the depositionofsandstonegrainsandclaylayers,processesofcarbonatecemen- tation and dissolution, and the mechanics of fracturing and folding. Good reservoirmodeldesignisthereforefoundedongoodgeologicalinterpretation. Thereisalwaysabalancebetweenprobability(theoutcomesofstochastic processes)anddeterminism(outcomescontrolledbylimitingconditions).We developtheargumentthatdeterministiccontrolsrootedinanunderstandingof geologicalprocessesarethekeytogoodmodeldesign.Theuseofprobabilis- ticmethodsinreservoirmodellingwithoutthesegeologicalcontrolsisapoor basis for decisionmaking, whereas anintelligent balancebetweendetermin- ismandprobabilityoffersapromisingpath. We also discuss the decision-making process involved in reservoir modelling.Human beingsarenotoriously badatmakinggood judgements– athemewidelydiscussedinthesocialsciencesandbehaviouralpsychology. Thesameappliestoreservoir modelling–howdoyouknowyouhaveafit- for-purpose reservoir model? There are many possible responses, but most commonly there is a tendency to trust the outcome of a reservoir modelling processwithoutappreciatingtheinherentuncertainties. We hope this book will prove to be a useful guide to practitioners and students of subsurface reservoir modelling in the fields of petroleum geosci- ence, environmental geoscience, CO and energy storage and reservoir 2 engineering – an introduction to the complex, fascinating, rapidly-evolving andmulti-disciplinaryfieldofsubsurfacereservoirmodelling. Trondheim,Norway PhilipRingrose Edinburgh,UK MarkBentley Tenby,UK Prologue: Model Design Successful Reservoir Modelling This book offers practical advice and ready-to-use tips on the design and construction of reservoir models. This subject is variously referred to as ‘geological reservoir modelling,’ ‘static reservoir modelling’, ‘3D reservoir modelling’ or ‘geomodelling’, and our starting point is very much the geol- ogy.However,theendpointisfundamentallytheengineeringrepresentation of the subsurface and in this sense these notes will deal with the important interfacewiththeworldofdynamic,simulationmodelling,withwhichstatic modellingisintrinsicallyintegrated. Our central argument is that whether models succeed in their goals is generally determined in the higher level issue of model design – building modelswhicharefitforthepurposeathand. Basedonourownexperiencesandthoseofcolleaguesandgroupswehave workedwithoncoursesandinreviews,wedistinguishfiverootcauseswhich commonlydeterminemodellingsuccessorfailure: 1. Establishingthemodelpurpose Whyareweloggedoninthefirstplaceandwhatdowemeanby‘fit-for- purpose’? 2. Buildinga3Darchitecturewithappropriatemodellingelements Thefluid-dependentchoiceonthelevelofdetailrequiredinamodel 3. Understandingdeterminismandprobability Ourexpectationsofgeostatisticalalgorithms 4. Modelscaling Reconcilingthejumpbetweenthescaleofdataandcellularresolutionof our models, and how to represent pore-scale fluid flow reasonably at a reservoirscale 5. Uncertainty-handling Movingfromsingletomulti-modelsandwherethedesignbecomessubject tobias Strategies for addressing these underlying issues will be dealt with in the following chapters under the thematic headings of model purpose, the rock model, the property model, upscaling flow properties and uncertainty- handling. vii viii Prologue:ModelDesign In the later chapters we focus on specific reservoir types, as there are generic issues which predictably arise when dealing with certain reservoirs. We look specifically at how our experiences from modelling hydrocarbon reservoirscanbeappliedtomodellingreservoirs(andtheiroverburdens)for disposal and storage of CO or hydrogen. We share our experience, gained 2 frompersonalinvolvementinoverahundredmodellingstudies,significantly augmented by the experiences of others shared in reviews and reservoir modellingclassesoverthepast30years. Beforeweengageintechnicalissues,however,areflectiononthecentral themeofdesign. Reservoirmodellersinfrontofrocks,discussingdesign(PhotographbyPhilipRingrose) Design in General Designisanessentialpartofeverydaylife,compellingexamplesofwhichare to be found in architecture. We are aware of famous, elegant and successful designs, such as the Gherkin – a striking feature of the London skyline designed for the Swiss Re company by Norman Foster and Partners – but we are more likely to live and work in less glamorous but hopefully fit-for- purpose buildings. The Gherkin, or more correctly the 30 St. Mary Axe building,useshalftheenergytypicallyrequiredbyanofficeblock,optimises the use of daylight and natural ventilation (Price 2009) and embodies both innovativeandsuccessfuldesign,althoughwithsignificantcomplexity. Prologue:ModelDesign ix There are many more examples, however, of office block and accommo- dation units that are unattractive and plagued by design faults and inefficiencies–thecarbunclesthatshouldneverhavebeenbuilt. This architectural analogy gives us a useful setting for considering the moreexclusiveartofconstructingmodelsofthesubsurface. NormanFosterbuilding,30St.MaryAxe(PhotographfromFosterandBlaser(1993)– reproducedwithkindpermissionfromSpringerScience+BusinessMediaB.V.) Whatconstitutesgooddesign?Inourcontextwesuggesttheessenceofa good design is simply that it fulfils a specific purpose and is therefore fit for thatpurpose. The Petter Daas museum in the small rural community of Alstahaug in northernNorwayoffersanotherarchitecturalstatementondesign.Thisfairly smallmuseum,celebratingalocalpoetanddesignedbythearchitecturalfirm Snøhetta,fitssnuglyandconsistentlyintothelocallandscape.Itiselegantand practical giving both light, shelter and warmth in a fairly extreme environ- ment.AlthoughlackingthecomplexityandscaleoftheGherkin,itisequally fit-for-purpose.Significantly,inthecontextofthisbook,itrisesoutfromand x Prologue:ModelDesign fitsintotheNorwegianbedrock.Itisanengineeringdesignclearlyfoundedin thegeology–theessenceofgoodreservoirmodeldesign. Whenwebuildmodelsoffluidresourcesinthesubsurfaceweshouldnever ignore the fact that those resources are contained within rock formations. Geologicalsystemspossesstheirownnaturalformsofdesignasdepositional, diagenetic and tectonic processes generate intricate reservoir architectures. Werelyonafirmreservoirarchitecturalfoundation,basedonanunderstand- ing of geological processes, which can then be quantified in terms of rock propertiesandconvertedintoaformusefultopredictfluidflowbehaviour. ThePetterDassMuseum,Alstahaug,Norway(ThePetterDass-museum,#PetterDass-museum, reproducedwithpermission) Good reservoir model design therefore involves the digital representation ofthenaturalgeologicalarchitectureanditstranslationintousefulmodelsof subsurface fluid resources. Sometimes the representations are complex – sometimestheycanbeverysimpleindeed. References FosterN,BlaserW(1993)Normanfostersketchbook.Birkhauser,Basel Price B (2009) Great modern architecture: the world’s most spectacular buildings.CanaryPress,NewYork
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