关键词: 川南地区, 深层页岩气, 压裂窜扰, 天然裂缝, 地应力, 裂缝扩展

Abstract: The development practice of deep shale gas in southern Sichuan Basin indicates that fracture-driven interactions (FDIs) dominated by negative impact severely affect the high-efficiency and beneficial development, which poses a great challenge to the long-term beneficial development of deep shale gas. By taking Luzhou block in southern Sichuan Basin as an example, the reservoir stress field inversion and natural fracture identification have been conducted to determine the combination characteristics of in-situ stress and natural fractures, as well as their influence on hydraulic fracture propagation, so as to avoid the occurrence of FDIs between deep shale gas horizontal wells. On this basis, the micro-seismic monitoring results in fracturing process of wells with FDI have been compared for verification, and the distribution characteristics of volume fracture network pattern have been analyzed to identify the intrinsic mechanism of FDIs between horizontal wells. Furthermore, based on the UFM model, a multi-well fracture propagation model has been established, focusing on the analysis of competing propagation law of multi-cluster fractures, so as to provide theoretical basis for avoiding FDIs between horizontal wells. The study results show that in the bulge area, the strata have dual characteristics of relatively low horizontal in-situ stress and well-developed stripe shaped natural fractures, and the induced hydraulic fractures are prone to propagation in this area, which are the key geological factors for FDIs between horizontal wells in the southern Sichuan Basin; In addition, due to the competing propagation of multi-cluster fractures, large-scale stripe shaped natural fractures have significant induction and capture effects on hydraulic fractures, which will cause excessive propagation of a certain cluster or side fractures, leading to fracture connection and FDIs between horizontal wells.