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1、第42卷第6期煤田地质与勘探Vol.42No.62014年12月COALGEOLOGY&EXPLORATIONDec.2014文章编号:1001-1986(2014)06-0044-06煤层气钻井过程中钻井液对煤岩储层损害评价1,2113陈德飞，康毅力，李相臣，陈飞(1.西南石油大学油气藏地质及开发工程国家重点实验室，四川成都610500；2.中国石油塔里木油田分公司油气工程研究院，新疆库尔勒；3.川庆钻探长庆井下技术作业公司，陕西西安710000)摘要:针对煤层气钻井过程中钻井液的侵入可能给煤岩储层造成的损害，选用宁武盆地9号
2、煤和现场用钻井液为研究对象，开展了煤样钻井液动–静态损害评价、毛细管自吸、应力敏感性评价等实验。钻井液动–静态损害评价表明，钻井液滤液损害是造成煤层渗透率下降的主要原因；与地层水相比，煤样对钻井液的自吸能力强且吸附滞留严重，导致液相返排率偏低；钻井液作用后弱化煤样力学性质强化了煤样应力敏感性。结合水敏、碱敏、润湿性评价和扫描电镜分析结果，指出钻井液作用后煤岩裂隙堵塞、润湿性差异和钻井液吸附是钻井液造成煤层损害的主要因素。关键词：煤层气；钻井液；储层损害；应力敏感；岩石力学中图分类号：P618.13文献标识码：ADOI:10.39
3、69/j.issn.1001-1986.2014.06.009Evaluationofreservoirdamagecausedbydrillingfluid1,2113CHENDefei,KANGYili,LIXiangchen,CHENFei(1.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitationinSouthwestPetroleumUniversity,Chengdu610500,China;2.ResearchInstituteofOilandGas
4、Engineering,TarimOilfieldCompany,PetroChina,Korla841000,China;3.ChangqingDownholeTechnicalServiceCompany,Xi′an710000,China)Abstract:AimingatreservoirdamagecausedbydrillingfluidinvasionduringCBMdrilling,thepaper,byselectingseamNo.9inNingwubasinanddrillingfluidusedinsi
5、teasresearchobject,conductedevaluationofdynamic-staticdamageofcoalsamplescausedbydrillingfluid,capillaryimbibitionandstresssensitivity.Dynamic-staticdamageevaluationshowsthatfiltratedamageofdrillingfluidisthemaincauseforreductionofpermeabilityincoalseam,coalimbibitio
6、nsabilityisstrongandadsorptionretentionisseriousfordrillingfluidwhencomparedwithformationwater,whichleadtothelowliquidphaseflow-back,afterbeingreactedwiththedrillingfluid,coalsampleshasweakenedmechanicalpropertiesandstrengthenedstresssensitivity.Incombinationwiththea
7、nalysisresultsofwatersensitivity,alkalisensitivity,wettabilityevaluationandscanningelectronmicroscopy(SEM),itispointedoutthatfractureblocking,wettabilitydifferenceanddrillingfluidadsorptionofcoalarethemainfactorsofseamdamagecausedbydrillingfluid.Keywords:CBM;drilling
8、fluid;reservoirdamage;stresssensitivity;mechanicalproperties[6]煤层一般经历的构造运动较多，导致内生裂隙严重。在低压储层选用不适当钻井液会减少煤层[7]破坏程度较大，煤层厚度较小，与常规储层相比，气的
