Investigations on the methane sorption capacity of marine shales from Sichuan Basin, China
Investigations on the methane sorption capacity of marine shales from Sichuan Basin, China
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四川盆地海相页岩甲烷吸附能力研究
DOI：
10.1016/j.coal.2015.05.009
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发表时间：
2015-07-01
影响因子：
5.6
通讯作者：
Krooss, Bernhard M.
中科院分区：
文献类型：
--
作者：
Yang, Feng;Ning, Zhengfu;Krooss, Bernhard M.
在中国四川盆地下志留统海相页岩上测量了 30,50 和 80 摄氏度以及高达 20 MPa 压力的高压甲烷吸附等温线。研究了总有机碳含量、温度、热成熟度、矿物组成和孔隙结构对甲烷吸附能力的影响。已经开发出一种线性组合方法，可以根据页岩的有机和无机组分的质量分数来预测页岩的朗缪尔吸附能力。该信息可用于估计页岩层的原位吸附能力，作为埋藏深度（地层压力和温度）和成分的函数。干燥页岩的甲烷吸附能力与 TOC 和比表面积呈正相关。朗缪尔压力随着成熟度的增加而降低，但过成熟页岩的 TOC 归一化朗缪尔吸附能力也随着热成熟度的增加而降低。这可能与高度过熟有机质的碳化有关。对于所研究的样品，大约 16.3%-46.7%（平均 28.6%）的甲烷吸附可归因于这些页岩中的粘土矿物，46.5%-81.5%（平均 67.6%）的有机质。采用线性组合方法，计算出的Langmuir吸附容量函数与测量值合理匹配。作为深度函数计算的甲烷吸附能力（平均静水压力梯度为 0.01 MPa/m，地温梯度为 0.03 °C/m）显示出快速增加，并在 900 至 1800 m 之间达到最大值，然后随着深度的增加缓慢下降。在浅埋藏深度（900-1800 m），吸附能力由地温梯度控制。较高的地温梯度导致吸附能力急剧下降。 (C) 2015 Elsevier B.V. 保留所有权利。
High-pressure methane sorption isotherms measured at 30,50 and 80 degrees C and pressure up to 20 MPa were measured on Lower Silurian marine shales from Sichuan Basin of China. The effect of total organic carbon content, temperature, thermal maturity, mineral composition, and pore structure on methane sorption capacity has been investigated. A linear combination approach has been developed to predict the Langmuir sorption capacity of shales based on the mass fractions of their organic and inorganic components. This information can be used to estimate the in situ sorption capacity of shale layers as a function of burial depth (formation pressure and temperature), and composition.Methane sorption capacity of the dry shales shows a positive relationship with TOC and specific surface area. The Langmuir pressure decreases with increasing maturity, but the TOC-normalized Langmuir sorption capacity of over-mature shales also decreases with increasing thermal maturity. This may be related to the carbonization of highly over-mature organic matter. For the samples investigated, approximately 16.3%-46.7% (average 28.6%) of the methane sorption can be attributed to clay minerals and 46.5%-81.5% to (average 67.6%) organic matter in these shales, respectively. Using the linear combination approach, the calculated Langmuir sorption capacity function matches the measured values reasonably. Methane sorption capacity computed as a function of depth (for a mean hydrostatic pressure gradient of 0.01 MPa/m and a geothermal gradient of 0.03 degrees C /m) shows a rapid increase and reaches a maximum between 900 and 1800 m followed by a slow decrease with increasing depth. At shallow burial depths (900-1800 m) sorption capacity is controlled by the geothermal gradient. Higher geothermal gradients result in a steeper decline of sorption capacity. (C) 2015 Elsevier B.V. All rights reserved.