Abstract The existing moisture in shale samples makes the evaluation for shale gas reservoirs more difficult due to its impact on the methane adsorption capacity and pore structure measurements. This paper compares the pore structure characteristics and methane adsorption capacity between dry and wet shale samples from Perth Basin, Western Australia. Pores with size between 0.4 nm and 100 nm were quantified by low-pressure N2 and CO2 adsorption. The comparative results demonstrate that moisture could alter the pore size distribution for big pores (>16 nm) and small pores (0.4–16 nm) in different ways. For each sample, the moisture effect on methane adsorption in shales changes with pressure: moisture effect on methane adsorption is more pronounced at lower pressure than higher pressure. For all samples, the effect of moisture on methane adsorption is related to the total organic carbon (TOC) content. Moisture could reduce methane adsorption by blocking clay- hosted small pores directly and organic matter-hosted small pores indirectly in high TOC samples. This phenomenon can effectively lead to a reduced Langmuir volume (VL) and increased Langmuir pressure (PL) when moisture exists.

中文翻译：

---

水分对页岩样品甲烷吸附能力的影响研究

摘要 页岩样品中存在的水分对甲烷吸附能力和孔隙结构测量产生影响，使得对页岩气藏的评价更加困难。本文比较了西澳大利亚珀斯盆地干湿页岩样品的孔隙结构特征和甲烷吸附能力。大小在 0.4 nm 和 100 nm 之间的孔隙通过低压 N2 和 CO2 吸附进行量化。比较结果表明，水分可以以不同的方式改变大孔（> 16 nm）和小孔（0.4-16 nm）的孔径分布。对于每个样品，水分对页岩中甲烷吸附的影响随压力而变化：水分对甲烷吸附的影响在低压下比高压下更明显。对于所有样本，水分对甲烷吸附的影响与总有机碳 (TOC) 含量有关。在高 TOC 样品中，水分可以通过直接阻塞粘土承载的小孔隙和间接阻塞有机质承载的小孔隙来减少甲烷吸附。当水分存在时，这种现象可以有效地导致朗缪尔体积 (VL) 减小和朗缪尔压力 (PL) 增加。