水力压裂微地震实验研究

微地震震源机制解包含储层及裂缝特征信息,对于地质力学建模和水力压裂储层评价都有十分重要意义.然而,目前微地震震源机制类型仍存在争议,该方面的基础实验仍需要进一步的研究.本文针对花岗岩和页岩两类岩石,开展了水力压裂微地震实验研究.在实验进行前,分析了实验条件和数据采集方式.根据实验室测定的岩石物性参数和各级检波器微震事件的P波初动信息等,利用射线追踪进行微震事件的反演定位.定位的结果同岩石CT扫描观测到的裂缝有较高吻合度.利用微震事件在各级检波器处的P波初动极性及检波器在岩石表面的位置信息,进行微地震事件的震源机制反演,得出了水力压裂实验下微地震震源机制以剪切型占优的结论.结合微地震事件定位结果,震源机制反演结果和岩石CT扫描裂缝结果等,进行对比和分析,得出了一些新的结论和认识,为今后的实际微地震监测裂缝解释提供指导意见.

Hydraulic fracturing micro-seismic experiment study

The micro-seismic focal mechanism contains important information about reservoir and fracture,which makes it great significance for geomechanical modeling and hydraulic fracturing reservoir evaluation.However,the focal mechanism types of microseismic are still controversial,and more research is needed on related basic experiments.In this paper,granite and shale are tested for this hydraulic fracturing micro-seismic experiment.We analyzed the experimental conditions and methods of data collection before the experimental.Based on the physical properties of rock and the first arrival information of P wave,the ray tracing inversion is used to locate the micro-seismic events.The location results are in good agreements with rock CT scanning.Then,the first arrival polarity of P wave together with position of each detector are used for focal mechanism inversion,and conclusion that shear-tensile tapy is the main part of the source mechanism of micro-seismic event under the hydraulic fracturing experiment.Analysis of micro-seimic location,focal mechanism and CT scanning gives us some new conclusions,which could be applied to practical micro-seismic monitoring fracture interpretation.