Hu Ke, Mischo Helmut
Institute of Mining and Special Civil Engineering, TU Freiberg, Freiberg, Sachsen 09599, Germany.
ACS Omega. 2020 Mar 2;5(10):5048-5060. doi: 10.1021/acsomega.9b03978. eCollection 2020 Mar 17.
Shale gas has attracted increasing attention as a potential alternative gas in recent years. Because a large fraction of gas in shale formation is in an adsorbed state, knowledge of the supercritical methane adsorption behavior on shales is fundamental for gas-in-place predictions and optimum gas recovery. A practical model with rigorous physical significance is necessary to describe the methane adsorption behavior at high pressures and high temperatures on shales. In this study, methane adsorption experiments were carried out on three Lower Silurian Longmaxi shale samples from the Sichuan Basin, South China, at pressures of up to 30 MPa and temperatures of 40, 60, 80, and 100 °C. The simplified local density/Elliott-Suresh-Donohue model was adopted to fit the experimental data in this study and the published methane adsorption data. The results demonstrate that this model is suitable to represent the adsorption data from the experiments and literature for a wide range of temperatures and pressures, and the average absolute deviation is within 10%. The methane adsorption capacity of the Longmaxi shale exhibited a strong linear positive correlation with the total organic carbon content and a linear negative correlation with increasing temperature. The rate of decrease in the methane adsorption capacity with swing temperature increased with the total organic carbon content, indicating that the organic matter is sensitive to temperature.
近年来，页岩气作为一种潜在的替代气体受到了越来越多的关注。由于页岩地层中的大部分气体处于吸附状态，了解超临界甲烷在页岩上的吸附行为对于原地气体预测和最佳气体采收率至关重要。需要一个具有严格物理意义的实用模型来描述高温高压下甲烷在页岩上的吸附行为。在本研究中，对来自中国南方四川盆地的三个下志留统龙马溪页岩样品进行了甲烷吸附实验，实验压力高达30MPa，温度为40、60、80和100℃。本研究采用简化的局部密度/埃利奥特-苏雷什-多诺休模型对实验数据以及已发表的甲烷吸附数据进行拟合。结果表明，该模型适用于表示广泛温度和压力范围内的实验和文献吸附数据，平均绝对偏差在10%以内。龙马溪页岩的甲烷吸附能力与总有机碳含量呈强线性正相关，与温度升高呈线性负相关。随温度变化甲烷吸附能力的下降速率随总有机碳含量的增加而增加，表明有机质对温度敏感。
