深层页岩气井压裂加砂工艺优化的微地震评价

Microseismic event evaluation for sand fracturing optimization in deep shale-gas wells

水力压裂是对页岩气致密储层进行改造的重要方法,但是埋深大于3500m的深层与浅层页岩气井压裂裂缝形态不同,二者压裂加砂工艺也有所差异。为了更有效开发深层页岩气,在压裂中优化加砂工艺,并利用压裂中微地震事件的展布特征评价加砂工艺的优化效果。四川盆地东南部深层页岩气井压裂加砂工艺研究结果表明:添加100目陶粒的压裂段微地震事件分布均匀且加砂量达到设计标准,微地震事件密度及储层改造体积较大;进行二次添加100目石英砂作业压裂段压裂裂缝长度、宽度、高度皆较大,远端事件数较多,储层改造体积有明显增加;五峰组微地震事件呈狭长分布,宽度及高度方向长度皆较小,压裂缝网内部微地震事件分布较均匀。通过微地震监测、评价深层页岩气井加砂工艺优化效果,可以更好地指导加砂作业和深层页岩气的开发。

Hydraulic fracturing is an important method for reforming tight reservoirs such as shale gas,but fracturing fractures morphology of deep shale-gas wells with buried depth greater than 3500 meters is quite different from that of shallow shale-gas wells,and the fracturing proppant filling process is also different from shallow shale-gas wells.This paper presents an example of proppant filling process optimization in a deep shale-gas well fracturing,and evaluates the optimization with distribution characteristics of microseismic events in fracturing.The monitoring results show that the distribution of microseismic events in the fractured section with 100 mesh ceramsite is uniform and the amount of proppant filling reaches the design standard,and the density of microseismic events and the stimulated reservoir volume are larger.With the second 100 mesh quartz proppant filling,the length,width and height of fracture in fracturing are larger,the number of distal events is larger,and the stimulated reservoir volume is also larger.Microseismic events in Wufeng Formation fracturing distribute in narrow and long shape.Our practice shows that microseismic event evaluation can achieve proppant filling process optimization in deep shale-gas wells in the deep shale gas development.