Permeability anisotropy of shale and tight gas reservoirs is critical for applications in unconventional gas recovery, but laboratory measurements are still limited. This paper presents an experimental method for determining permeability anisotropy of shale and tight reservoirs. The method uses gas production data from a canister and an analytical solution of continuity equation in anisotropic core sample. Axial permeability and transverse permeability of the core are estimated by matching experimental data with analytical solution. The proposed method is verified by comparing with true values and calculated values through numerical simulations that cover variations in rock permeability. The method is applied to real data measured in canister degassing tests (CDT) involving two different directional shale core samples. Then, the experimental results are compared with the results from pulse pressure decay (PPD) method. Both the verification from numerically calculated results and the comparison between PPD results and CDT results exhibit the practicality of the proposed method. At last, the effects of permeability anisotropy, porosity, initial gas pressure, rock dimensions, and adsorption on the profiles of gas production are investigated.

中文翻译：

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罐脱气试验同时确定致密油藏岩心轴向渗透率和横向渗透率的方法

页岩和致密气藏的渗透率各向异性对于非常规天然气采收中的应用至关重要，但是实验室测量仍然受到限制。本文提出了一种确定页岩和致密油藏渗透率各向异性的实验方法。该方法使用了来自碳罐的产气数据和各向异性岩心样品中的连续性方程的解析解。岩心的轴向渗透率和横向渗透率是通过将实验数据与解析解进行匹配来估算的。通过覆盖岩石渗透率变化的数值模拟，通过与真实值和计算值进行比较来验证所提出的方法。该方法适用于在罐脱气测试（CDT）中测量的真实数据，该测试涉及两个不同方向的页岩岩心样品。然后，将实验结果与脉冲压力衰减（PPD）方法的结果进行了比较。数值计算结果的验证以及PPD结果与CDT结果的比较都表明了该方法的实用性。最后，研究了渗透率各向异性，孔隙率，初始气压，岩石尺寸和吸附对产气剖面的影响。