氣水兩相煤層氣井井底流壓預(yù)測(cè)方法

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1、氣水兩相煤層氣井井底流壓預(yù)測(cè)方法第31卷第6期2010年11月石油ACTAPETR0LEISINICAVol_31NO.6NOV.2O1O文章編號(hào):0253—2697(2010)06—0998—06氣水兩相煤層氣井井底流壓預(yù)測(cè)方法劉新福綦耀光劉春花李延祥趙培華.(1.中國(guó)石油大學(xué)機(jī)電工程學(xué)院山東東營(yíng)257061;2中國(guó)石油煤層氣有限責(zé)任公司北京100011)摘要:基于井筒流體穩(wěn)定流動(dòng)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(cè)方法,并分析了各排采參數(shù)間的相互關(guān)系及其對(duì)產(chǎn)能的影響.研究結(jié)果表明,該算法較為準(zhǔn)確地預(yù)測(cè)了煤層氣井進(jìn)入穩(wěn)定排

2、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(zhǎng)度不超過(guò)25m時(shí),井底流壓預(yù)測(cè)結(jié)果的相對(duì)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(dòng)液面較高時(shí),宜加大排液量,降低井底壓力,而動(dòng)液面較低時(shí),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(hào):TE349文獻(xiàn)標(biāo)識(shí)碼:APredictionofflowingbottomholepressuresfortwo—p

3、hasecoalbedmethanewellsLIUXinfuQIYaoguang'LIUChunhuaLIYanxiangZHAOPeihua(1.CollegeofMechanicalandElectronicEngineering,ChinaUniversityofPetroleum,Dongying257061,China;2.PetroChinaCoalbedMethaneCompanyLimited,Beijing1()0OI1,China)Abstract:Flowingbottomholepressure(FBHP)inthecoalbedmethane(CBM

4、)wellsisthekeyparameterofdeterminingthedeliver—abilityofcoalfields.Periodiccalculationandsupervisionofbottomholepressures(BHP)canpredictfuturereservoirbehaviorandhelptOadjusttheworkingsystem.Themathematicalmodelsofgascolumnpressureandtwo—phaseliquidcolumnpressurewerede—velopedbasedontheCBMwe

5、llliquidflowequation.ThepredictionofFBHPwasgivenoutfortwo—phaseCBMwells.Andtherelationshipamongoperationalparametersandtheireffectsondeliverabilitywereanalyzedonthebasisofresults.TheresultsshowthattheproposedalgorithmprovidesaccuratepredictionforFBHPinCBMwells.BHPresultsfromthecombinedaction

6、ofwellheadpres—sure,gascolumnpressureandtwophasefluidcolumnpressure.AndBHPcanfullyreflectpercolationcharacteristicsofCBMproduc—tion.BHPisafunctionofdepthofeachcolumnsegment,andthesmallerrorsoflessthan5%areachievedwhileeachsegmentiswithin25m.AdjustingBHPduringtheproductioncaneffectivelyincrea

7、seproducingpressuredropandcontrolwaterflowrate,whichisbeneficialtOgasdesorptionandenhanceCBMproduction.BHPcanbedecreasedduetoincreasingwaterdisplacementwhiledynam—icfluidlevelishighanddecreasingwellheadpressurewhileitisrelativelylow.Keywords:coalbe