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1、氣水兩相煤層氣井井底流壓預(yù)測方法第31卷第6期2010年11月石油ACTAPETR0LEISINICAVol_31NO.6NOV.2O1O文章編號:0253—2697(2010)06—0998—06氣水兩相煤層氣井井底流壓預(yù)測方法劉新福綦耀光劉春花李延祥趙培華.(1.中國石油大學(xué)機電工程學(xué)院山東東營257061;2中國石油煤層氣有限責任公司北京100011)摘要:基于井筒流體穩(wěn)定流動能量方程,建立了煤層氣柱段壓差和兩相液柱壓差的數(shù)學(xué)模型,給出了氣水兩相煤層氣井底流壓的預(yù)測方法,并分析了各排采參數(shù)間的相互關(guān)系及其對產(chǎn)能的影響.研究結(jié)果表明,該算法
2、較為準確地預(yù)測了煤層氣井進入穩(wěn)定排采后的井底流壓;井底流壓是井口套壓,氣柱和液柱壓力綜合作用的結(jié)果,能充分反映產(chǎn)氣量的滲流壓力特征;該模型充分考慮了井筒中壓力增量隨井深增量的變化關(guān)系,在兩相液柱段每等份長度不超過25m時,井底流壓預(yù)測結(jié)果的相對誤差可控制在5%以內(nèi);調(diào)整井底壓力,可有效增大生產(chǎn)壓差,控制排液量,利于煤層氣體的解吸,從而提高產(chǎn)氣量;產(chǎn)水量較大,動液面較高時,宜加大排液量,降低井底壓力,而動液面較低時,宜放開套壓.關(guān)鍵詞:煤層氣井;井底流壓;煤層氣柱壓力;兩相液柱壓力;產(chǎn)能中圖分類號:TE349文獻標識碼:APredictionof
3、flowingbottomholepressuresfortwo—phasecoalbedmethanewellsLIUXinfuQIYaoguang'LIUChunhuaLIYanxiangZHAOPeihua(1.CollegeofMechanicalandElectronicEngineering,ChinaUniversityofPetroleum,Dongying257061,China;2.PetroChinaCoalbedMethaneCompanyLimited,Beijing1()0OI1,China)Abstract:Flo
4、wingbottomholepressure(FBHP)inthecoalbedmethane(CBM)wellsisthekeyparameterofdeterminingthedeliver—abilityofcoalfields.Periodiccalculationandsupervisionofbottomholepressures(BHP)canpredictfuturereservoirbehaviorandhelptOadjusttheworkingsystem.Themathematicalmodelsofgascolumnp
5、ressureandtwo—phaseliquidcolumnpressurewerede—velopedbasedontheCBMwellliquidflowequation.ThepredictionofFBHPwasgivenoutfortwo—phaseCBMwells.Andtherelationshipamongoperationalparametersandtheireffectsondeliverabilitywereanalyzedonthebasisofresults.Theresultsshowthatthepropose
6、dalgorithmprovidesaccuratepredictionforFBHPinCBMwells.BHPresultsfromthecombinedactionofwellheadpres—sure,gascolumnpressureandtwophasefluidcolumnpressure.AndBHPcanfullyreflectpercolationcharacteristicsofCBMproduc—tion.BHPisafunctionofdepthofeachcolumnsegment,andthesmallerrors
7、oflessthan5%areachievedwhileeachsegmentiswithin25m.AdjustingBHPduringtheproductioncaneffectivelyincreaseproducingpressuredropandcontrolwaterflowrate,whichisbeneficialtOgasdesorptionandenhanceCBMproduction.BHPcanbedecreasedduetoincreasingwaterdisplacementwhiledynam—icfluidlev
8、elishighanddecreasingwellheadpressurewhileitisrelativelylow.Keywords:coalbe
