资源环境科技发展态势分析平台

In the southern Sichuan Basin, China, the recent increase in the seismic activity has been suspected to be related to hydraulic fracturing stimulation for producing the shale gas. In this study, we used the monitoring data from a local seismic network within the shale gas blocks to study the earthquakes near the shale gas production wells that have detailed injection data. Comparison of the timing of earthquakes and stimulation schedule of the studied well pads indicates an apparent correlation between the seismic activity and hydraulic fracturing. The results of seismic velocity tomography reveal that the reactivation of preexisting faults due to fluid diffusion is the primary cause of the observed earthquakes. Focal mechanism analysis combined with geomechanical modeling indicates that the increased pore pressures resulted from hydraulic fracturing are sufficient to trigger seismic slip on the faults.

Plain Language Summary Starting in 2014, felt earthquakes have increased significantly in the southern Sichuan Basin, China. The hydraulic fracturing stimulation used for producing the shale gas in this area is suspected to be responsible for the increase of the seismic rate. This study analyzed the seismic monitoring and well injection data to investigate the relationship between the recorded earthquakes and hydraulic fracturing at the shale gas well pads. The results presented in this study indicate that fluid diffusion from hydraulic fracturing triggers the slip of preexisting faults and causes the occurrence of small earthquakes.