The effective stress coefficient is an essential geomechanical parameter required for estimation of the effective stress acting upon the subsurface reservoir porous rock formations and affecting their petrophysical properties. The values of the effective stress coefficient for various rock properties depend on the complex phenomena involving various types of rock deformation and alteration processes. This paper presents a discussion of the relevant factors and an effective method for accurate correlation of the Biot–Willis effective stress coefficient by means of a kinetics-based phenomenological model. This is accomplished by developing a modified power-law equation which describes the variation of the effective stress coefficient by various rock deformation and alteration processes at a macroscopic scale. This equation has five parameters which can be determined using the experimental data obtained by rock testing. The modified power-law equation is derived in a manner to satisfy the low- and high-end limit conditions of the effective stress coefficient exactly, which are the zero and unity values, respectively, for the Biot–Willis effective stress coefficient associated with the bulk volumetric strain. However, many empirical correlations presented in the literature cannot satisfy the low- and high-end limit values of the effective stress coefficient. The modified power-law equation is applied for correlation of the Biot–Willis effective stress coefficient associated with the bulk volumetric strain as functions of porosity, permeability, permeability/porosity ratio, and stress using the experimental data of various porous subsurface rock formations and artificial porous materials. The quality of the correlations is determined by means of the coefficient of regression or correlation and the root mean-square of the difference of the correlation values relative to the measured data. The correlation of the Biot–Willis coefficient with porosity yields the best results compared to the correlations obtained with permeability and permeability/porosity ratio. The stress dependence of the Biot–Willis effective stress coefficient of heterogeneous rock formations involving the slope change and hysteresis effects is correlated to describe the slope discontinuity caused by the deformation process transition and the hysteresis caused by the inertial and delay effects, fully elastic pre-damage, and/or irreversible rock damage during loading/unloading.

有效应力系数是估算作用在地下储层多孔岩层上并影响其岩石物理性质的有效应力所需的基本地质力学参数。各种岩石特性的有效应力系数值取决于涉及各种类型的岩石变形和蚀变过程的复杂现象。本文讨论了有关因素，并通过基于动力学的现象学模型对比奥-威利斯有效应力系数进行精确关联的有效方法进行了讨论。这是通过开发改进的幂律方程来实现的，该方程描述了宏观尺度下各种岩石变形和蚀变过程引起的有效应力系数的变化。该方程具有五个参数，可以使用通过岩石测试获得的实验数据来确定。修改后的幂律方程的推导方式可以精确地满足有效应力系数的低端和高端限制条件，分别对应于与应力相关的毕奥特-威利斯有效应力系数的零值和单位值。体积体积应变。但是，文献中提出的许多经验相关性都不能满足有效应力系数的低端和高端极限值。修改后的幂律方程用于将与大体积应变相关的毕奥–威利斯有效应力系数与孔隙率，渗透率，渗透率/孔隙率的函数相关，利用各种多孔地下岩层和人工多孔材料的实验数据来分析应力和应力。相关性的质量取决于回归系数或相关系数以及相关值相对于测量数据之差的均方根。与通过渗透率和渗透率/孔隙率比获得的相关性相比，比奥-威利斯系数与孔隙率的相关性产生了最好的结果。涉及坡度变化和滞后效应的非均质岩层的毕奥–威利斯有效应力系数的应力相关性，用于描述变形过程过渡引起的边坡不连续性以及惯性和延迟效应，全弹性预应力引起的滞后。损害，