The influence of fracturing process on microseismic propagation

In the hydraulic fracturing process, the velocity model for microseismic location is usually constructed by well logs, seismic data or calibration shots which ignore the influence of the fracturing process. In this work, we examine its influence by simulating microseismic events and pore pressure variation in the fracturing process. Besides the microseismicity produced by hydraulic fracture extension, we also simulate the microseismicity caused by fluid leakage by means of the critical pore pressure criterion. The Coates-Schoenberg method and fracture compliances are then applied to calculate the real-time velocity in the fracturing process, and 3D ray tracing method is applied to compare the microseismic propagation variation in the different stages of the fracturing process. The results of the simulation show that the deviation caused by the fracturing process varies considerably between different receiver locations, and the overall deviation increases with the fracturing process. Finally, a new method is constructed to evaluate the travel time deviation in real data.