Abstract Relative permeability is one of the most important parameters in reservoir modeling. However, measurements of relative permeability in unconventional reservoir rocks are rare, and the influence of relative permeability hysteresis on reservoir studies has not previously been addressed. This paper presents a systematic investigation of gas-water relative permeability and hysteresis based on a laboratory technique developed through our previous work. Gas relative permeability was measured using the modified gas expansion method under the scenario of drainage and subsequent imbibition. Water relative permeability was estimated based on Brooks-Corey (1956) equations. Results of gas-water relative permeability that cover a broader range of saturation than that in our previous work were obtained. Causes of relative permeability hysteresis are discussed in detail. The laboratory-based gas-water relative permeability of one of the samples is compared to history-matched results from the literature, and upscaling of the laboratory result is discussed on the basis of this comparison. Finally, the potential influence of relative permeability hysteresis on water and gas production after hydraulic fracturing and shut-in is illustrated through a conceptual model and quantitative analysis. Gas production rates can be overestimated after hydraulic fracturing when hysteresis is ignored. Shut-in can enhance gas production rates significantly. Enhancement of production rate is greater at the initial phase, but it diminishes later, after continuous expansion of the imbibition zone. This work presents the first known study of gas-water relative permeability hysteresis in unconventional reservoir rocks.

中文翻译：

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非常规储层岩体气水相对渗透率：关井后滞后及对产量的影响

摘要 相对渗透率是储层建模中最重要的参数之一。然而，非常规储层岩石中相对渗透率的测量很少，而且相对渗透率滞后对储层研究的影响以前没有得到解决。本文基于通过我们之前的工作开发的实验室技术，对气水相对渗透率和滞后进行了系统研究。气体相对渗透率采用改进的气体膨胀法在排水和后续渗吸的情况下进行测量。根据 Brooks-Corey (1956) 方程估计水的相对渗透率。气水相对渗透率的结果覆盖了比我们以前工作更宽的饱和度范围。详细讨论了相对渗透率滞后的原因。将其中一个样品的基于实验室的气水相对渗透率与文献中的历史匹配结果进行比较，并在此比较的基础上讨论了实验室结果的升级。最后，通过概念模型和定量分析说明了相对渗透率滞后对水力压裂关井后产水产气的潜在影响。如果忽略滞后现象，水力压裂后的天然气产量可能会被高估。关井可以显着提高产气率。初期增产幅度较大，但随着渗吸带不断扩大，后期增产幅度逐渐减弱。