Fracture Microseismic Detection and Characteristics of Changyang Shale Gas Test Well

Based on the data of the seismic swarm occurred in Changyang area recorded by the Three Gorges Reservoir seismic network from July 2017 to August 2017, the high-resolution seismic catalog of the fracturing seismic swarm of the Changyang shale gas test well was constructed through the relocation processes of PhaseNet for seismic phase identification, REAL for earthquake association, HypoInverse for absolute relocation, and HypoDD for relative relocation. The relocation results of the swarm showed that the seismic sequence as a whole was spread in a band along the ground surface from south to north. The seismic activity in the Changyang area was very low before and after the hydraulic fracturing of the Changyang test wells. However, during the start of fracturing of the test well, the overall seismic activity increased dramatically with a maximum magnitude of M_L3.4, but the swarm activity had little impact on the seismic activity in the surrounding area. This swarm may be generated by the activation of the Tianyangping fracture due to the hydraulic fracturing of the shale gas extraction test well.