Experimental study on the synchronous propagation law of multiple fractures with interference between joints in deep coal measure reservoir

In order to study the synchronous propagation law of multiple fractures with interference between joints in deep coal measure reservoir,the self-developed “TCHFSM-I” large-size true triaxial fracturing seepage simulation device was used to carry out experiments on the effects of different fracturing hole spacing and different fluid injection rates on the synchronous propagation law of multiple fractures. The fracture growth pattern,evolution law of fluid injection pressure,dynamic response characteristics of acoustic emission and evolution characteristics of fluid injection flow during fracturing process were observed and analyzed. The results show that: when the fracturing hole spacing is small,the fracture extension length on both sides is larger than that of the middle fracture, and the three fractures expand evenly with the increase of fracturing hole spacing. Increasing the injection rate can increase the fracture initiation pressure, increase the length of multiple fractures, and effectively increase the reservoir reconstruction volume. Increasing the fracturing hole spacing and injection rate can make the proportion of liquid injection in the left, middle and right fracturing holes more balanced.