Experimental study and modelling of methane adsorption and diffusion in shale
Experimental study and modelling of methane adsorption and diffusion in shale
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DOI：
10.1016/j.fuel.2013.09.046
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发表时间：
2014-01
期刊：
影响因子：
7.4
通讯作者：
Weina Yuan;Z. Pan;Xiao Li;Yunxia Yang;Chun-xia Zhao;L. Connell;Shouding Li;Jianming He
中科院分区：
文献类型：
--
作者：
Weina Yuan;Z. Pan;Xiao Li;Yunxia Yang;Chun-xia Zhao;L. Connell;Shouding Li;Jianming He
了解页岩中天然气的储运机制对储层评价和天然气产量预测具有重要意义。页岩基质具有复杂的孔隙结构，大小从纳米到微米不等。尽管扩散在页岩气在储集层中的运移中起着重要作用，但对页岩中天然气扩散的系统研究还很少。研究了基于孔隙结构的页岩甲烷扩散行为，以及样品粒度和含水率对天然气吸附扩散的影响。结合N2吸附和扫描电子显微镜实验结果表明，页岩样品具有双峰孔径分布。双分散模型能较好地描述扩散数据，其参数与N2吸附和扫描电子显微镜的孔径分布结果一致。研究发现，Fickian扩散和Knudsen扩散在页岩气扩散中都起着重要的作用，它们表现出不同的气体压力依赖关系。吸附等温线和计算的扩散系数与颗粒大小关系不大。然而，在潮湿的样品中，天然气的吸附和扩散系数显著降低，表明水降低了页岩中的天然气存储能力和运移速度。
Understanding gas storage and transport mechanisms in shale is crucial for reservoir evaluation and gas production forecast. The shale matrix has a complex pore structure, with sizes ranging from nanometres to micrometres. Although diffusion plays a significant role in shale gas transport in the reservoir, systematic studies of gas diffusion in shale are rare. This paper studied the methane diffusion behaviour of shale based on pore structure, as well as the effects of sample particle size and water on gas adsorption and diffusion. The combined N2adsorption and SEM experimental results showed that the shale sample had a bimodal pore size distribution. The diffusion data were able to be described adequately by the bidisperse model, and the parameters were consistent with pore size distribution results obtained from the N2adsorption and SEM results. It was found that both Fickian diffusion and Knudsen diffusion play important roles in shale gas diffusion and they show different gas pressure dependence. Adsorption isotherm and calculated diffusivity showed little particle size dependence. However, gas adsorption and diffusivity were significantly reduced in moist samples, showing that water reduces gas storage capacity and transport rate in shale.