Research progress on isotopic fractionation in the process of shale gas/coalbed methane migration

作者：Wenbiao Li, Shuangfang Lu, Junqian Li, Yongbo Wei, Shengxian Zhao, Pengfei Zhang, Ziyi Wang, Xiao Li, Jun Wang · 发表于：Petroleum Exploration and Development · 年份：2022 · DOI：10.1016/s1876-3804(22)60333-1 · 被引用次数：43 · 研究领域：Hydrocarbon exploration and reservoir analysis、Coal Properties and Utilization、Methane Hydrates and Related Phenomena

The research progress of isotopic fractionation in the process of shale gas/coalbed methane migration has been reviewed from three aspects: characteristics and influencing factors, mechanism and quantitative characterization model, and geological application. It is found that the isotopic fractionation during the complete production of shale gas/coalbed methane shows a four-stage characteristic of “stable-lighter-heavier-lighter again”, which is related to the complex gas migration modes in the pores of shale/coal. The gas migration mechanisms in shale/coal include seepage, diffusion, and adsorption/desorption. Among them, seepage driven by pressure difference does not induce isotopic fractionation, while diffusion and adsorption/desorption lead to significant isotope fractionation. The existing characterization models of isotopic fractionation include diffusion fractionation model, diffusion-adsorption/desorption coupled model, and multi-scale and multi-mechanism coupled model. Results of model calculations show that the isotopic fractionation during natural gas migration is mainly controlled by pore structure, adsorption capacity, and initial/boundary conditions of the reservoir rock. So far, the isotope fractionation model has been successfully used to evaluate critical parameters, such as gas-in-place content and ratio of adsorbed/free gas in shale/coal etc. Furthermore, it has shown promising application potential in production status identification and decline trend pre...