微地震监测技术是水力压裂中监测裂缝发育情况的有效地震方法,但在实际应用中仍存在诸多问题.为此,开展了地面微地震震源机制反演及裂缝解释技术在四川盆地页岩气藏勘探中的应用研究.根据地面观测的微地震数据,采用矩张量反演获得微地震事件的震源机制;基于震源机制结果计算微地震事件震级以及裂缝的地质参数;在统计的裂缝地质参数上解释裂缝发育情况,为油藏描述提供有效的信息.四川盆地页岩气实际资料的应用结果表明,研究区水平井的压裂设计合理,发育裂缝为高角度缝;根据统计的裂缝方位角度和实际的地下应力状况,建立了走滑型剪切裂缝模型;在裂缝模型上了解局部最大、最小水平应力方向,建议井布置方位在现有方位上调整为北偏西约10°.%Microseismic monitoring technology is an effective approach for in-situ monitoring of fracture growth during hydraulic fracture stimulations.However,there are still many problems in practical application.We evaluate the progression of focal inversion and fracture interpretation from surface microseismic monitoring with emphasis on the application in shale exploration of Sichuan Basin.According to the receiver data on surface survey,the focal mechanism of microseismic events is obtained with the moment tensor inversion.The grade of microseismic events and fracture geological parameters are accessed from focal mechanism.The fracture interpretation based on the statistics of geology parameters could provide detailed information for reservoir characterization.The result of actual data from some basin in Sichuan processing proves that the fracturing design of horizontal well in this study area is reasonable.The grown fracture is steeply dipping.The strike-slip shear fracture mode is built from the statistics of fracture azimuths and geological stress condition.Base on the interpreted fracture model,the directions of local maximum and minimum horizontal stresses are derived and the orientation adjustment of existing well location is suggested to the north west of about 10°.
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