To evaluate the risk of induced seismicity due to hydraulic fracturing, a detailed stress analysis in a seismically active region, i.e., the Changning shale-gas field in the southern Sichuan Basin, was conducted utilizing sonic wave velocity logs and high-resolution electrical resistivity image logs of shale gas wells. Wells with relatively higher magnitudes of horizontal stresses are spatially located in the vicinity of thrust faults, in agreement with the stress concentration at the upper tip of the basement-involved thrust fault. The prevailing orientation of maximum horizontal principal stress (S_Hmax) is N110°–120°E on the southwestern Changning anticline, which aligns with the motion of the Sichuan Basin, as driven by the continuous eastward extrusion of the Tibet plateau, which initiated at approximately 50 Ma. However, the S_Hmax orientation is N30°–70°E along the northern Changning anticline, implying an inheritance of the N–S geodynamic compression during the Jurassic to Late Cretaceous. Drilling-induced tensile fractures primarily appear in compliant layers that are rich in clay or organic matter in wells located adjacent to thrust faults, suggesting that stiff layers can efficiently inhibit the hydrofracture growth height owing to more intense tectonic stress near thrust faults. A natural fault with a strike of approximately 30° to the S_Hmax orientation can be more easily activated by extreme pumping pressure in wells that are weakly affected by the stress concentration along the thrust fault. Nevertheless, a cyclic injection of fracturing fluid with a gradually increasing target pressure may effectively reduce the magnitude of induced seismicity.

为了评估水力压裂诱发地震活动的风险，利用声波速度测井和高分辨率电阻率图像对地震活动区，即四川盆地南部的长宁页岩气田进行了详细的应力分析。页岩气井的日志。水平应力相对较高的井在空间上位于逆冲断层附近，与基底卷入逆冲断层上端的应力集中一致。最大水平主应力 (S _Hmax) 是长宁西南部背斜的 N110°–120°E，与四川盆地的运动一致，这是在青藏高原持续向东挤压的驱动下，在大约 50 Ma 开始。然而，沿长宁背斜北部的 S _Hmax方向为 N30°–70°E，暗示继承了侏罗纪至晚白垩世 N-S 地球动力学压缩。钻井引起的拉伸裂缝主要出现在位于逆冲断层附近的井中富含粘土或有机物的柔顺层中，这表明由于逆冲断层附近更强烈的构造应力，刚性层可以有效地抑制水力压裂的生长高度。走向与 S _Hmax成大约 30° 的自然断层在受逆冲断层应力集中影响较弱的井中，通过极端泵送压力可以更容易地激活定向。尽管如此，循环注入压裂液并逐渐增加目标压力可以有效地降低诱发地震的震级。