Abstract Analyzing gas flow behavior is important for production prediction in heterogeneous fractured shale reservoirs, which is complex due to the presences of nanopores and high-degree heterogeneity in these complex flow network. First, we applied the discrete fracture model to simulate gas pulse-decay experiments in core plugs with different configurations. The effective permeability ratio was proposed to evaluate the effects of heterogeneity, fracture, and vug on the flow behavior. Second, we performed pulse-decay experiments on one intact fractured shale core to examine the effects of pore pressure and effective stress on permeability variations. The measured pressure profiles were history matched by numerical methods to obtain the porosity and permeability of matrix and fracture. The matching degree is evaluated by the Global Matching Error (GME). Our results highlight the positive impact of dense fracture network to improve flow capacities in the tight reservoir: effective permeability of the fractured core with 8 pairs of 1.3-cm connected fractures increases 4.07 times that of the un-fractured core. Vugs might be important as well if they connect adjacent fracture networks, but their own contribution to flow capacity is negligible: effective permeability increases only 1.00 to 1.02 times when the number of vugs increase from 3 to 35. The GME ranges from 0.04% to 0.2% for history matching of the fractured core. Core heterogeneity is exhibited more obviously when gas flows through under low pressure than under high pressure, which can be used to guide the design of pulse-decay experiment properly depending on the purpose. The main contributions of this study are that we constructed the finite-element based numerical model to simulate the pulse-decay experiment, proposed a methodology to upscale core permeability when fractures and vugs are present, and measured porosity and permeability for the matrix and fracture simultaneously in one fractured core over a wide range of pressure and effective stress.

中文翻译：

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非均质裂缝性致密多孔介质渗透率的实验和数值研究

摘要 分析气体流动行为对于非均质裂缝性页岩储层的生产预测很重要，由于这些复杂流动网络中纳米孔的存在和高度非均质性，该储层很复杂。首先，我们应用离散裂缝模型来模拟具有不同配置的岩心塞中的气体脉冲衰减实验。提出有效渗透率比来评估非均质性、裂缝和孔洞对流动行为的影响。其次，我们对一个完整的裂隙页岩岩心进行了脉冲衰减实验，以检查孔隙压力和有效应力对渗透率变化的影响。测得的压力剖面通过数值方法进行历史匹配，以获得基质和裂缝的孔隙度和渗透率。匹配度由全局匹配误差（GME）评估。我们的结果突出了致密裂缝网络对提高致密储层流动能力的积极影响：具有 8 对 1.3 厘米连接裂缝的裂缝岩心的有效渗透率是未裂缝岩心的 4.07 倍。如果它们连接相邻的裂缝网络，孔洞可能也很重要，但它们对流动能力的贡献可以忽略不计：当孔洞数量从 3 增加到 35 时，有效渗透率仅增加 1.00 到 1.02 倍。 GME 范围从 0.04% 到 0.2 % 用于断裂岩心的历史匹配。气体在低压下流过时岩心的非均质性比高压下表现得更明显，可以根据目的适当指导脉冲衰减实验的设计。