Ao Xiang, Qi Zhilin, Xiang Zuping, Li Zhiqiang, Qu Hai, Wang Ziyi
Chongqing Key Laboratory of Complex Oil and Gas Field Exploration & Development, Chongqing University of Science and Techology, Chongqing 401331, China.
Chongqing Key Laboratory of Heavy Oil Exploitation, Chongqing University of Science and Techology, Chongqing 401331, China.
ACS Omega. 2020 Jul 30;5(31):19606-19614. doi: 10.1021/acsomega.0c02118. eCollection 2020 Aug 11.
Shale gas is a promising energy source offering additional energy security over concerns of fossil fuel depletion. Injecting CO into depleted shale gas reservoirs might provide a feasible solution for CO storage and enhanced gas recovery. However, shale strain caused by the CO injection as well as CO sequestration in the reservoir needs to be considered during shale gas production. For this purpose, this paper examines the adsorption capacities, CO-induced swelling, and He-induced strain of shales at 0-16 MPa and 35-75 °C. The maximum excess adsorption at different temperatures correlated with the bulk phase density: as the CO temperature increased, the maximum excess adsorption density decreased. The density of the adsorbed phase, obtained using the Dubinin-Radushkevich model, was used to fit the excess adsorption data. At low pressure, the CO-induced strain on shale was caused by the gas adsorption, whereas at high pressure, it was caused by gas pressure. The absolute adsorption linearly correlated with the adsorption-induced strain.
页岩气是一种很有前景的能源，在应对化石燃料枯竭问题上提供了额外的能源安全保障。向枯竭的页岩气储层注入二氧化碳可能为二氧化碳封存和提高气体采收率提供一个可行的解决方案。然而，在页岩气生产过程中需要考虑注入二氧化碳引起的页岩应变以及二氧化碳在储层中的封存情况。为此，本文研究了页岩在0-16兆帕和35-75℃条件下的吸附容量、二氧化碳引起的膨胀以及氦引起的应变。不同温度下的最大过量吸附与体相密度相关：随着二氧化碳温度升高，最大过量吸附密度降低。使用杜比宁-拉杜舍维奇模型获得的吸附相密度用于拟合过量吸附数据。在低压下，二氧化碳对页岩的应变是由气体吸附引起的，而在高压下，则是由气体压力引起的。绝对吸附与吸附引起的应变呈线性相关。
