低渗油藏注水诱发微细缝扩展模型研究

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1、中图分类号：TE345单位代码：11414学号：2014212178题目低渗油藏注水诱发微细缝扩展模型研究学科专业油气田开发工程研究方向油气田开发理论与系统工程硕士生周禹指导教师于海洋（副教授）二○一七年五月摘要摘要长庆低渗透油藏实际生产动态资料表明，注水井储层附近诱发了微细缝，目前对于注水诱发微细缝影响因素、开启扩展机理和规律的研究较少，因此，弄清注水诱发微细缝开启扩展机理及注水井附近微细缝分布规律，对于提高低渗油藏开发效果具有重要的理论和现实意义。本文首先利用动态资料分析存在诱发缝油水井的动态特征，然后研究注水诱发微细缝开启扩展机理，得出了注水过程温度和压力控制储

2、层应力变化。长期注水使地层孔隙压力升高、地层温度降低，在压力和温度变化双重作用下使地应力重新分布且地层最小主应力降低，基于有裂缝注水井应力场模型，裂缝水平方向应力降低值大于垂直方向应力降低值，则注水过程中裂缝起裂阻力减小。最后建立考虑应力变化的注水诱发微细缝数学模型，通过数值模拟，研究了注水井井筒附近温度变化，在注水过程中裂缝延伸压力逐渐减小，井底压力产生波动，裂缝半长和缝宽随着注水时间增加而增大。关键词：低渗油藏；注水诱发微细缝；温度；裂缝扩展；数值模拟-II-ABSTRACTStudyonthemicro-fracturepropagationmodelbywat

3、er-injectioninducedinlowpermeabilityreservoirsABSTRACTThefieldproductiondynamicdatashowthatthereareinducedmicro-fracturesneartheinjectionwellinChangqinglowpermeabilityreservoir.Atpresent,therearefewstudiesonthefactorsaffectingthemicro-fracture,mechanismandtheregularityoffractureinitiati

4、onandpropagationinducedbywaterinjection.Therefore,makingcleartheinitiationandpropagationmechanismoftheinducedmicro-fractureandthedistributionregularityneartheinjectionwellsareveryimportant,whichhassignificanttheoreticalandpracticalsignificanceforimprovingtherecoveryoflowpermeabilityrese

5、rvoir.Firstweusethedynamicdatatoanalyzethedynamiccharacteristicsofoilandwaterwells,whichexisttheinducedfractures.Thenweresearchthemechanismofthefractureinitiationandpropagationinducedbywater-injection,itisconcludedthatpressureandtemperaturecontrolthestresschangesduringwaterinjection.The

6、long-termwater-injectionincreasestheporepressureandreducesthetemperature,duetodualeffectsofpressureandtemperaturechanges,thein-situstressisredistributedandthemini-principalstressisreduced.Basedonthestressfieldmodeloffracturedwaterinjectionwells,thestressreductioninthehorizontaldirection

7、ofthefractureisgreaterthanthestressreductionintheverticaldirection,andthefractureinitiationresistancedecreasesduringthewater-injection.Finallyweestablishthemathematicalmodelofmicro-fractureinducedbywater-injectionconsideringthestresschange,throughnumericalsimulationweanalyzethe