Fast and accurate characterization of unconventional gas reservoirs is of great significance for estimation of gas-in-place and enhancement of gas recovery; however, it remains a big challenge to efficiently and effectively determine the permeability of tight-structure reservoirs in the nano-Darcy scale, especially for those reservoirs with strong gas sorption potential. A novel pressure transient technique is proposed to replicate the in-situ gas flow behavior, and thus to reduce the permeability errors from gas compressive storage, gas sorption, and gas compressibility, which are the three primary error sources widely existing in various permeability measurement techniques. The feasibility of the technique is firstly verified via numerical solutions of a partial differential equation (PDE) model established to closely represent the proposed technique. The results of the numerical study showed that the effects of the error sources on the measured permeability can be minimized and meanwhile, high accuracy and efficiency can be achieved in comparison with the conventional method. A specially designed apparatus for experimental tests via the proposed technique is then used to investigate the stress-dependent permeability of gas shales. The consistency of the experimental results with the findings from the numerical study further validates the applicability of the technique. Considering the complexity of the analytical solution of the PDE model for experimental data interpretation, shale permeability is computed via a new data interpretation approach which is developed by combining the curve-matching and the finite difference method. The experimental results showed that shale permeability is strongly dependent upon the applied stresses and easily affected by gas sorption, gas compressibility and stress inhomogeneity. Without consideration of these factors, the permeability error can reach up to 28.1 % at low stresses. The proposed technique provides a great tool to get insights into the in-situ gas flow behavior and characterize tight-structure gas reservoirs.

快速准确地表征非常规气藏对于评价天然气储量和提高采收率具有重要意义；然而，在纳米达西尺度上有效地确定致密结构储层的渗透率仍然是一个很大的挑战，特别是对于那些具有强气体吸附潜力的储层。提出了一种新的压力瞬变技术来复制原位气体流动行为，从而减少气体压缩存储、气体吸附和气体压缩性的渗透率误差，这是各种渗透率测量技术中广泛存在的三个主要误差源。该技术的可行性首先通过建立的偏微分方程 (PDE) 模型的数值解来验证，该模型密切代表所提出的技术。数值研究结果表明，与常规方法相比，可以最大限度地减少误差源对渗透率测量的影响，同时具有较高的精度和效率。然后使用专门设计的通过所提出的技术进行实验测试的设备来研究气页岩的应力相关渗透率。实验结果与数值研究结果的一致性进一步验证了该技术的适用性。考虑到实验数据解释PDE模型解析解的复杂性，采用曲线匹配法与有限差分法相结合的新数据解释方法计算页岩渗透率。实验结果表明，页岩渗透率强烈依赖于施加的应力，容易受到气体吸附、气体压缩性和应力不均匀性的影响。如果不考虑这些因素，低应力下的渗透率误差可达 28.1%。所提出的技术提供了一个很好的工具来深入了解 考虑到实验数据解释PDE模型解析解的复杂性，采用曲线匹配法和有限差分法相结合的新数据解释方法计算页岩渗透率。实验结果表明，页岩渗透率强烈依赖于施加的应力，容易受到气体吸附、气体压缩性和应力不均匀性的影响。如果不考虑这些因素，低应力下的渗透率误差可达 28.1%。所提出的技术提供了一个很好的工具来深入了解 考虑到实验数据解释PDE模型解析解的复杂性，采用曲线匹配法与有限差分法相结合的新数据解释方法计算页岩渗透率。实验结果表明，页岩渗透率强烈依赖于施加的应力，容易受到气体吸附、气体压缩性和应力不均匀性的影响。如果不考虑这些因素，低应力下的渗透率误差可达 28.1%。所提出的技术提供了一个很好的工具来深入了解 页岩渗透率是通过一种新的数据解释方法计算的，该方法是结合曲线匹配和有限差分方法开发的。实验结果表明，页岩渗透率强烈依赖于施加的应力，容易受到气体吸附、气体压缩性和应力不均匀性的影响。如果不考虑这些因素，低应力下的渗透率误差可达 28.1%。所提出的技术提供了一个很好的工具来深入了解 页岩渗透率是通过一种新的数据解释方法计算的，该方法结合了曲线匹配和有限差分方法。实验结果表明，页岩渗透率强烈依赖于施加的应力，容易受到气体吸附、气体压缩性和应力不均匀性的影响。如果不考虑这些因素，低应力下的渗透率误差可达 28.1%。所提出的技术提供了一个很好的工具来深入了解原位气体流动行为和表征致密结构气藏。