Abstract Pressure depletion of hydrocarbon reservoirs can cause re-activation along fault planes of weakness, resulting in geomechanical hazards such as seismicity. The article presents analytical solutions of conditions leading to mechanical fault reactivation. The developed methodology starts by defining various fault categories present in the Dutch subsurface based on reservoir setting and fault properties, such as throw, dip, strike and transmissibility. For all fault categories initiation criteria for fault re-activation have been developed based on a new Coulomb stability relationship. The depletion-induced poro-elastic stress changes depend on the reservoir geometry and the fault transmissibility while the induced shear stresses are determined from differential vertical displacement profiles. The induced shear stress is either caused by the fault throw or by the pressure difference caused by the (partly) sealing fault or at the boundary fault. Analysis of the Coulomb stability function allows determination of the relative importance of poro-elastic stressing relative to differential compaction. The critical reservoir pressure depletion for fault re-activation to occur has been determined for open, intra-reservoir faults with or without a throw, (partly) sealing intra-reservoir faults and boundary faults. Satisfying this Coulomb criterion is the first necessary mechanical condition for seismicity to occur. These results can be used to determine the initiation pressures for seismicity to occur in depleting gas reservoirs in The Netherlands and can in addition explain why the observed seismicity has been attributed to steeply dipping fault planes.

中文翻译：

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枯竭油藏断层再活化机理分析

摘要 油气藏的压力枯竭会导致沿薄弱断层面的重新激活，从而导致地震活动等地质力学灾害。本文介绍了导致机械故障重新激活的条件的分析解决方案。开发的方法首先根据储层环境和断层特性（例如断层、倾角、走向和传输率）定义荷兰地下存在的各种断层类别。对于所有故障类别，故障重新激活的启动标准已根据新的库仑稳定性关系制定。耗尽引起的孔隙弹性应力变化取决于储层几何形状和断层传导率，而引起的剪切应力由不同的垂直位移剖面确定。诱发剪应力要么由断层引发，要么由（部分）封闭断层或边界断层引起的压力差引起。库仑稳定性函数的分析允许确定多孔弹性应力相对于压实的相对重要性。对于断层重新激活发生的临界储层压力消耗已经确定为有或没有断层的开放、储层内断层、（部分）封闭储层内断层和边界断层。满足该库仑准则是发生地震活动的第一个必要力学条件。