微生物采油技术在中国胜利油田罗801区块的试验A英文译文2.docx

微生物采油技术在中国胜利油田罗801区块的试验A英文译文2.docx

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微生物采油技术在中国胜利油田罗801区块的试验A英文译文2

微生物采油技术在中国胜利油田罗801区块的试验A-英文译文2

MEORFieldtestatBlockLuo801ofShengliOilFieldinChina

Abstract

AMicrobialEnhancedOilRecovery（MEOR）fieldtesthasbeenimplementedfor10consecutiveyearsatthe75℃-80℃BlockLuo801inShengliOilFieldinChina,wheremicrobialformulationandnutrient,producingbiosurfactant,wereinjectedintooilwells.AftertheimplementationofMEOR,theproducedfluidsamplesfromtheoilwellswereanalyzedandfoundanincreaseofbacteriaandarchaeainwaterphasestabilizingat103-4cell/mlandasoarofacetateinconcentrationfrom70mg/Lto523.0mg/Lwithoutfindingthetypeofinjectedmicrobialtypes,suggestingthenutrientinjectedhasactivatedtheindigenousbacteriainthereservoir,whoseactivitieswereenhancedtopreventthewatercutfromrisingupintheblocksoastoincreasetheoiloutput.UptoDecember2010,thecumulativeincreasedproductionofoilhasbeen9.75×104twiththetotaloutputsurpassingthatofWaterFloodingOilRecovery（WFOR）by3.35%.Consideringthecostofinjectedmicrobialfluidandnutrient,oilincreasedpertonnecostsaboutRMB339.56.

Keywords:

MicrobialEnhancedOilRecovery（MEOR）,FieldTest,WaterFlooding

1.Introduction

FaultblockoilreservoirsoccupyanimportantproportioninShengliOilFieldofChina,whosedevelopedgeologicalreserveshavereached9.22×108tbutwiththecomprehensivewatercut91.5%.Thushowtostoptheproductiondeclineandenhancethecrudeoilrecoverybecomesamajorchallengetodevelopfaultblockoilreservoirswithhighwatercut.Duetothesmallerareabearingoilandtheincompleteproductionwellgrid,itisnotsuitabletocarryoutchemicalenhancedoilrecoverytechnologyforfaultblockoilreservoirsandalternativeoilrecoverytechnologyisexpectedtobedevelopedforthem.MicrobialEnhancedOilRecovery（MEOR）technologyisconsideredpromisingforfaultblockoilreservoirs,whoserelatedresearchwasnotlauncheduntil1990sinShengliOilFieldbyaspecializedteamengagedinresearchandtestinMEOR.Oncetheirpurposewastoselectthebacteriatype,suitableforthereservoirenvironmentandcapabletoenhancetheoildisplacementefficiently,whichwasfirstgroundculturedtheninjectedintothereservoirs.Atthebeginningofthiscentury,researchrevealedindigenousbacteriainreservoirsareveryactive,sotheresearchfocusshiftedtoindigenousbacteriaenhancedoilrecovery.Currently,oilreservoirshavebeenconsideredasanecosystemintowhichmaterialsuchasspecificmicrobialformulation,inorganicororganicnutrientandairhavebeeninjectedtoregulatethem:

themicrobialcommunitystructureandfunctioninsidemightchange,increasingthebacteriadensity,producingbiosurfactantandimprovingtheoil-washefficiencythrough"insitubreeding".Basedonresearchinthelaboratory,aMEORfieldtesthasbeencarriedoutinBlockLuo801inShengliOilFieldsince1999.Thetestmethodhasbeenadjustedtwiceinthe10yearperiodinthehopeofexploringthepotentialofMEORtechnologytoimproveoilrecoveryinfaultblockoilreservoirs.

2.TestAreaReservoirGeology

BlockLuo801isasmallblockinShengliOilField,alithologic-structuralreservoirwithatemperaturerangingfrom75℃to80℃.Itisopeninthenorthandthesouthernpartisclosedbyaneast-westarcfault,wherethetestareaislocatedonthehangingwall.Theareabearingoilis​​1.95km2withthecrudeoilreserves291×104t.Thereservoirdepthisfrom1680mto1800mandtheoriginalformationpressureis17.5MPa.

TheoilpoolofthetestareaislocatedontheWestWingofthenose-likestructure,whosestrataarehighinthesouthandlowinthenorthwithananglerangingfrom5ºto6º.ItpassesthroughPermianstrataincludingShahejieFm.,DongyingFm.,GuantaoFm.andPingyuanFm.asalakephasemesoporousandmeso-permeablereservoir,whoseoilbearingunitsareS1,S3,S4ofsandsection.withanaverageporosity23.5%,anaveragepermeability211.6⨯10-3μm2,andthegroundoilviscosity221.7mPa.s,formationwatertypeNaHCO3andTDS7795mg/L.TestareareservoirparametersareshowninTable1andthewells’positionisshowninFigure1.

Table1MEORtestareareservoirparametersofLuo801

Item

Data

Item

Data

Oilbearingarea（km2）

1.25

FormationwaterTDSmg/L

9794

Reserves（104t）

291

Formationwatertype

NaHCO3

Reservoirtype

lithologic-structural

Originaloilandgasratio

30

Reservoirdepth（m）

1680-1800

Originalformationpressure（MPa）

17.5

Porosity（%）

23.4

Saturationpressure（MPa）

9.24

Airpermeability（10-3um2）

218

Formationsaturationpressuredifference（MPa）

8.26

Oilsaturation（%）

60

Currentformationpressure

10

Groundcrudeoilviscosity（MPa.S）

353

Formationpressure℃

75-80

Figure1TectonicpositionofMEORtestareainLuo801

3.TestAreaDevelopmentProcess

Lou801hasbeenformallydevelopedsinceMay1994,inJune1998floodingoilrecoverybeganhere,inJuly1999thefirstMEORfieldtestlaunchedandin2003airaidedMEORbegantodevelop.Accordingtothetestareaproductioncurve,thedevelopmentcanbedividedintofourstages,namelycapacitybuildingstage,naturalenergydevelopmentstage,floodingdevelopmentstageandMEORteststage.

3.1CapacityBuildingStage,1994

WellsLuo801and805havebeenfinisheddrillinginBlockLuo801inAprilandMay1994respectively.SinceindustrialoilflowobtainedinS3andS4,theblockwasunderrollingdevelopmentasinthesameyear,anoilbearingareaof1.25km2wentintooperationinvolvingoilreserves291×104twithanewproductioncapability6×104t.InDecember1994,16wellswereopenedandproduced446toffluidand417tofoilperdaywiththewatercut6.5%,oilproductionrate5.23%,recoverypercentage3.16%,outputting9.2097×104tofoilannually.

3.2NaturalEnergyDevelopmentStage,1995–May1998

Thisstagefeaturesrelyingonnaturalenergywhenthereservoirwasdevelopedatahighspeed.Withtheformationpressuredroppingrapidly,theproductiondeclinedfastwhenitfellfrom17.34MPato6.47MPawithapressuredropupto10.87MPa,lessthan30%ofthesaturationpressure9.24MPa.Theelasticyieldis3.81⨯104t/MPa.Theannualoutputofoildecreasedfromthehighest11.9×104tto6.3×104t,withtheannualdeclining12%.Lateinthisstage,16wellswereopen,producing328.3tofliquidand195.3tofoilperdaywiththewatercut40.5%,whoseworkingfluidlevelwas958m.Inthisstage,theoiloutputreached30.3114×104tattherecoverypercentage10.4%.Cumulativeoilproductionwas39.5211×104tcovering13.58%ofthereserves.

3.3FloodingDevelopmentStage,June1998-June1999

BlockLuo801wasdevelopedbyfloodinginJune1998,firstwithWellsL801-7,L801-15,L801-17.Attheendofthisstage,13wellswereopen,producing259.6tofliquidand96.7tofoilperdaywiththewatercut62.8%.Theworkingfluidlevelwas1399m.Atthisstage,2.3612×104tofoil,0.81%ofthereserves,wasobtained.Thecumulativeoilproductionreached41.8823×104t,14.39%ofthereserves.

3.4MEORTestStage,July1999-December2010

MEORwaslaunchedinLuo801inJuly1999.Intheinitialphase,micro-organismswasinjectedintothreeinjectionwells（L801-7,L801-15,L801-17）,inSeptember2002therecoverypatternwasadjustedtohavethemiddletwoinjectionwells（L801-3,L801-18）injectedwiththeaidofaircompressorsinjectingair.

AsofDecember2010,14oilwellsinLuo801wereputintooperation,12wereopenedandproducing448.2tofliquidand60.3tofoilperday.Thecumulativeoilrecoverywas85.6572×104twiththewatercut86.5%,covering28.17%ofthereserves.Theoilproducingratewas0.77%.Atotaloffiveinjectionwellswereopened,injecting316.2m3perdaywithacumulativeinjection110.023×104m3.Themonthlyinjection-productionratiowas0.71andthecumulativeinjection-productionratiowas0.40.TwoMEORtestwellswereinjectedwith145m3ofwaterperday.

4.OverviewofMEORFieldTestImplementation

TheimplementationofMEORfieldtestofBlockLuo801canbedividedintotwophases.July1999toSeptember2002istheroutineMEORphase,whenmicrobialliquidandnutrientwereinjectedfromthethreesideinjectionwells.Theliquidcontains4typesofbacteria,producingsimilarsubstanceasbiosurfactant;mainingredientsofthenutrientsolutionweresugarandasmallamountofinorganicsalt.11wellswereaffectedinthetest.Byperiodicinjectiontechnique,thebacterialliquidandnutrientsolutionwereinjectedintotheformationonceevery20dayswithwater.September2002toDecember2010istheairaidedMEORphase.Airinjectionequipmentwasadopted.Microbialliquidandnutrientsolutionwereinjectedintotwomiddlewells（L801-3,L801-18）oftheblock,affecting14wells.Inadditiontowaterinjectionnormally,airwasinjected12hoursaday.

AstoDecember2010,3235tofbacterialiquid,3475tofsolidnutrientand36.41×104Nm3ofairwereinjected.

5.AnalysisofTestResults

AftertheimplementationofMEOR,theoverallcomprehensivewatercutincreasingisinhibitedinthetestarea,thenaturaldeclineofproductionissloweddownandthedailyoilproductionrisessteadily.Especiallyaftertheimplementationofair-aidedMEOR,theproductionisbetterthanMEORstageandapparentlybetterthantheproductionstatusbeforethetest.

5.1AffectofMEORonComprehensiveWaterCutofOilWellsinTestArea

Afterchangingintothewaterinjectionrecovery,thewatercutincreasingreachedashighasupto8.43%.DuringtheimplementationofMEOR,thewatercutincreasingsignificantlysloweddown.Thewatercutincreasingratehasbeenlessthan1%