New experimental tests on a suite of tight gas sandstone samples show a strong dependence of both P- and S-wave velocities, V_p and V_s, on hydrostatic confining stress in the range from almost zero to 50 MPa. The Klinkenberg-corrected absolute gas permeability of these samples also exhibited a dramatic stress dependence. It decreased by one to two orders of magnitude as the stress increased. A new approach is used to consolidate the 18-sample dataset at each confining stress and arrive at the effective permeability and elastic moduli. For the former, we utilize a randomly generated permeability matrix with its elements drawn from the 18 datapoints. For the latter, we use the elastic bounds. As a result, we obtain permeability-stress, porosity-stress, and velocity-stress relations characteristic of the class of rock under examination. Theoretical simulations based on the inclusion-based differential effective medium theory mimic the experimental velocity-stress results. We also derive a permeability versus acoustic impedance and versus stress relation to be used for inferring permeability variations as a function of the measured impedance versus stress changes. This relation can serve to estimate the permeability from the elastic property variations during time-lapse monitoring, as well as during fracking of this rock.

在一组致密气砂岩样品上进行的新实验测试表明，P波和S波速度，V _p和V _s都具有很强的依赖性，在静水压应力范围从零到50兆帕。这些样品经克林肯伯格校正后的绝对气体渗透率也表现出显着的应力依赖性。随着应力的增加，它减少了1-2个数量级。一种新方法用于在每个约束应力下合并18个样本的数据集，并得出有效的渗透率和弹性模量。对于前者，我们利用随机生成的渗透率矩阵，其元素来自18个数据点。对于后者，我们使用弹性边界。结果，我们获得了所检查岩石类别的渗透率应力，孔隙率应力和速度应力关系特性。基于包含物的微分有效介质理论的理论模拟模拟了实验速度-应力结果。我们还推导了磁导率与声阻抗以及应力关系的关系，用于推断磁导率变化与所测阻抗与应力变化的关系。这种关系可以用来在时滞监测以及岩石压裂过程中根据弹性特性的变化来估算渗透率。