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 investigate the effects of the fracturing hole spacing and 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.The three fractures expand evenly with the increase of fracturing hole spacing.A increased injection rate enhances the fracture initiation pressure and therefore promotes the length of multiple fractures and the volume of reservoir reconstruction.Large fracturing hole spacing and injection rate could achieve a more balanced injection rate in the left, middle and right fracturing holes.