Abstract Shale generally contains water that has a significant effect on the adsorption of methane in shale. Since methane in shale is mostly stored in an adsorbed state, understanding the effect of moisture on shale adsorption behavior will play a vital role in shale gas development. In this paper, an adsorption model has been proposed to consider the effects of moisture to describe the methane adsorption behavior in wet shale. The model modified the actual methane gas pressure in reservoirs, which to evaluate accurately the methane adsorption levels in the reservoir. Moreover, the model also quantitatively described the degree of influence that moisture in shale had on the amount of shale methane adsorbed. Published data have been used to further verify the applicability of the model. Results have shown that, during a change in gas pressure, the methane adsorption amount in shale revealed a typical “three-stage” change law. With an increase in moisture, the methane adsorption level decreased linearly owing to the inhibitory effect of water molecules on methane adsorption. In terms of test data matching, the calculated results of the model were in approximate agreement with the measured values, indicating that the model could better describe the adsorption behavior in aquifers. Additionally, the classic Langmuir model, the Langmuir-Freundlich model, and the D-A model have been used as comparison with the proposed model in this paper. The comparison results showed that the model proposed in this paper could better quantify the effects of moisture on methane adsorption. And it possessed advantages over models, such as the Langmuir one, under high pressure conditions. In addition, because of the hydrophilic nature of shale, methane could only be adsorbed at a lower energy adsorption site, which indicated that the adsorption heat on wet shale was significantly lower than that in dry shale.

中文翻译：

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不同压力和水分条件下评估页岩甲烷吸附能力的吸附模型

摘要 页岩中普遍含有水分，对页岩中甲烷的吸附作用显着。由于页岩中的甲烷大多以吸附状态储存，了解水分对页岩吸附行为的影响将在页岩气开发中发挥至关重要的作用。在本文中，已经提出了一个吸附模型来考虑水分的影响来描述湿页岩中的甲烷吸附行为。该模型修正了储层中的实际甲烷气体压力，以准确评估储层中的甲烷吸附水平。此外，该模型还定量描述了页岩中水分对页岩甲烷吸附量的影响程度。已发布的数据已被用于进一步验证模型的适用性。结果表明，在气体压力变化期间，页岩甲烷吸附量呈现典型的“三级”变化规律。随着水分的增加，由于水分子对甲烷吸附的抑制作用，甲烷吸附水平线性下降。在试验数据匹配方面，模型计算结果与实测值基本吻合，表明该模型能较好地描述含水层中的吸附行为。此外，经典的 Langmuir 模型、Langmuir-Freundlich 模型和 DA 模型已被用于与本文提出的模型进行比较。对比结果表明，本文提出的模型可以更好地量化水分对甲烷吸附的影响。在高压条件下，它比 Langmuir one 等模型更具优势。此外，