ENHANCED OIL RECOVERY IN SHALE AND TIGHT RESERVOIRS JAMES J. SHENG GulfProfessionalPublishingisanimprintofElsevier 50HampshireStreet,5thFloor,Cambridge,MA02139,UnitedStates TheBoulevard,LangfordLane,Kidlington,Oxford,OX51GB,UnitedKingdom ©2020JamesSheng.PublishedbyElsevierInc.Allrightsreserved. Nopartofthispublicationmaybereproducedortransmittedinanyformorbyanymeans, electronicormechanical,includingphotocopying,recording,oranyinformationstorageand retrievalsystem,withoutpermissioninwritingfromthepublisher.Detailsonhowtoseek permission,furtherinformationaboutthePublisher’spermissionspoliciesandourarrangements withorganizationssuchastheCopyrightClearanceCenterandtheCopyrightLicensingAgency, canbefoundatourwebsite:www.elsevier.com/permissions. Thisbookandtheindividualcontributionscontainedinitareprotectedundercopyrightbythe Publisher(otherthanasmaybenotedherein). Notices Knowledgeandbestpracticeinthisfieldareconstantlychanging.Asnewresearchand experiencebroadenourunderstanding,changesinresearchmethods,professionalpractices,or medicaltreatmentmaybecomenecessary. Practitionersandresearchersmustalwaysrelyontheirownexperienceandknowledgein evaluatingandusinganyinformation,methods,compounds,orexperimentsdescribedherein.In usingsuchinformationormethodstheyshouldbemindfuloftheirownsafetyandthesafetyof others,includingpartiesforwhomtheyhaveaprofessionalresponsibility. Tothefullestextentofthelaw,neitherthePublishernortheauthors,contributors,oreditors, assumeanyliabilityforanyinjuryand/ordamagetopersonsorpropertyasamatterofproducts liability,negligenceorotherwise,orfromanyuseoroperationofanymethods,products, instructions,orideascontainedinthematerialherein. LibraryofCongressCataloging-in-PublicationData AcatalogrecordforthisbookisavailablefromtheLibraryofCongress BritishLibraryCataloguing-in-PublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary ISBN:978-0-12-815905-7 ForinformationonallGulfProfessionalPublishingpublications visitourwebsiteathttps://www.elsevier.com/books-and-journals Publisher:JoeHayton SeniorAcquisitionEditor:KatieHammon EditorialProjectManager:AleksandraPackowska ProductionProjectManager:SelvarajRaviraj CoverDesigner:MarkRogers TypesetbyTNQTechnologies Contents Acknowledgments ix 1. Introduction to shaleand tight reservoirs 1 1.1 Introduction 1 1.2 Definitionsofshaleandtightreservoirs 2 1.3 Shaleandtightresources 6 1.4 Currentproductiontechnologies 6 2. Huff-n-puff gas injection in oilreservoirs 7 2.1 Introduction 7 2.2 Initialsimulationstudiesofhuff-n-puffgasinjection 8 2.3 Experimentalmethods 9 2.4 Effectofcoresize 18 2.5 Effectsofpressureandpressuredepletionrate 20 2.6 Effectofsoakingtime 25 2.7 EORperformancewithnumberofcycles 29 2.8 Effectofinjectedgascomposition 31 2.9 Minimummisciblepressure 37 2.10 Effectofdiffusion 41 2.11 Effectofwatersaturation 43 2.12 Effectofstress-dependentpermeability 45 2.13 Huff-n-puffmechanisms 46 2.14 Gaspenetrationdepth 51 2.15 Fieldprojects 54 3. Asphalteneprecipitationanddepositioninahuff-n-puffprocess 61 3.1 Introduction 61 3.2 Experimentsofasphalteneprecipitationandpermeabilityreduction 61 3.3 Depositionmechanisms 69 3.4 Numericalanalysis 71 3.5 Effectofasphaltenedepositiononhuff-n-puffoptimization 75 4. Huff-n-puff injection in shale gas condensate reservoirs 81 4.1 Introduction 81 4.2 Experimentalsetup 83 4.3 Huff-n-puffgasinjection 84 j v vi Contents 4.4 Huff-n-puffversusgasflooding 86 4.5 Core-scalemodelingofgasandsolventperformance 91 4.6 Reservoir-scalemodelingofgasandsolventperformance 98 4.7 Afieldcaseofmethanolinjection 101 4.8 Surfactanttreatment 102 4.9 Factorsthataffecthuff-n-puffgasinjectionperformance 105 4.10 Optimizationofhuff-n-puffinjection 109 4.11 Mechanismsofhuff-n-puffinjection 110 5. Optimization ofhuff-n-puff gas injection in shale and tight oilreservoirs 117 5.1 Introduction 117 5.2 Setupofabasesimulationmodel 118 5.3 Optimizationprinciples 121 5.4 Optimizationcriteria 122 6. Gasflooding compared with huff-n-puffgas injection 133 6.1 Introduction 133 6.2 Researchresultsongasflooding 133 6.3 Gasfloodingversushuff-n-puffgasinjection 137 6.4 Fieldapplicationsofgasflooding 145 6.5 Feasibilityofgasflooding 149 7. Water injection 151 7.1 Introduction 151 7.2 Waterflooding 151 7.3 Waterhuff-n-puffinjection 156 7.4 Waterfloodingversushuff-n-puffwaterinjection 162 7.5 Waterinjectionversusgasinjection 162 7.6 Water-alternating-gas(WAG) 166 7.7 Huff-n-puffwaterandsurfactantinjection 166 7.8 WaterinjectioninChina 167 8. Fluid-rock interactions 173 8.1 Introduction 173 8.2 Evidencesofmicrofracturesgeneratedorexistingnatural fracturesreopened 173 8.3 Effectofconfiningstress 179 8.4 Effectofbedding 186 8.5 Effectofexistingnaturalfractures 186 8.6 Permeabilitychangesfromwater-rockinteractions 187 Contents vii 8.7 Effectonrockmechanicalproperties 191 8.8 Furtherdiscussionsandsummaryofviewsandhypotheses 194 8.9 Effectoflow-pHandcarbonatedwater 197 8.10 Effectofhigh-pHwater 202 8.11 Coolingeffectofinjectedwater 204 8.12 Reaction-inducedfractures 205 8.13 Surfactanteffects 212 9. EOR mechanismsof wettability alteration and its comparison with IFT 213 9.1 Introduction 213 9.2 Mechanismsofinterfacialtension(IFT)reduction 214 9.3 Mechanismsofwettabilityalterationonoilrecovery 217 9.4 MathematicaltreatmentsofwettabilityalterationandIFTeffect 220 9.5 IFTreductionversuswettabilityalteration 226 9.6 SpecificsurfactantEORmechanismsrelatedtoshaleand tightformations 236 9.7 Surfactantselectionforwettabilityalteration 242 9.8 Determinationofwettability 253 9.9 Conversionofwettingangles 276 9.10 Moreonwettabilityofshaleandtightformations 277 10. Spontaneous imbibition 279 10.1 Introduction 279 10.2 Discussionofsometheoreticalequationsonspontaneousimbibition 279 10.3 Effectofpermeabilityandporosity 285 10.4 Effectofinitialwettabilityandwettabilityalteration 290 10.5 Effectofinterfacialtension(IFT) 293 10.6 Effectofdiffusion 296 10.7 Effectofgravity 297 10.8 Effectofviscosityratio 301 10.9 Effectofinitialwatercontent 301 10.10 Countercurrentflowversuscocurrentflow 301 10.11 Behaviorsofdifferentsurfactants 303 11. Forced imbibition 309 11.1 Introduction 309 11.2 Descriptionofabaseshalemodel 310 11.3 Shalerockversussandrock 315 11.4 Relativepermeabilitychangeversuscapillarypressurechange 321 11.5 Effectofcapillarypressure 322 viii Contents 11.6 Effectofpressuregradient(injectionrate) 326 11.7 Experimentalstudyofforcedimbibition 331 11.8 FieldtestsofsurfactantEOR 336 12. Fracturing fluidflow back 339 12.1 Introduction 339 12.2 Fieldobservationsandexperimentalresultsonflowback 341 12.3 Proposedmechanismsoflowflowback 345 12.4 Effectofshut-intimeonflowback 359 12.5 Shut-intimeeffectonfractureconductivity 375 12.6 Effectofinitialwettabilityonflowback 379 12.7 Effectofinvasiondepthonflowbackefficiencyandlatetimeoilrate 385 12.8 Effectofsurfactantsonflowback 390 12.9 Solutionstodealwithflowback 395 13. Air injection 401 13.1 Introduction 401 13.2 Laboratoryexperimentalfacilities 402 13.3 Kineticparameters 407 13.4 Oxidationreactions 427 13.5 Spontaneousignition 435 13.6 Oxygenconsumptionrateinlow-temperatureoxidation 452 13.7 Minimumoilcontentforcombustion 453 13.8 Airrequirementincombustion 453 13.9 EORmechanismsandEORpotentialinshaleandtightreservoirs 454 14. Other enhancedoil recoverymethods 457 14.1 Introduction 457 14.2 Sequentialmethodofhuff-n-puffCO injectionand 2 surfactant-assistedspontaneousimbibition 457 14.3 Chemicalblends 458 14.4 Airfoamdrive 460 14.5 Branchedfractures 461 14.6 Zipperfracture 462 14.7 Refracturing 463 14.8 Diversiontechnologyinfracturing 463 14.9 Energizedfluids 464 14.10 Thermalrecovery 464 14.11 MicrobialEOR 467 Nomenclature 469 References 475 Index 513 Acknowledgments This book summarizes some of my research results about shale EOR technologies in the past decade. Some of the dissertation or research work from my ex-PhD students, ex-postdoctoral students, and current PhD studentsisusedandcitedtosupport myviewsinthisbook.Theyare Yang Yu, Lei Li, Ziqi Shen, Siyuan Huang, Yao Zhang, Sharanya Sharma, Xingbang Meng, Nur Wijaya, Srikanth Tangirala, Tao Wan, Samiha Morsy,ShifengZhang,HuJia,JunrongLiu,TalalDaouGamadi,andJiawei Tu. Some of the work published by other authors is cited. Their work is sincerely acknowledged. Ihavedevotedmuchofmytimetomycareerdevelopment.Iowemuch tomywifeYingZhang,mydaughtersEmilyandSelena,andmyparentsJifa Sheng and Shouying Liu. If my life could be rechosen, I would have reallocated my time to them. Some of the research work was supported by the US department of Energy under Award Number DE-FE0024311, Apache Corporation, and ConocoPhillips. j ix