Effect of Pre-Adsorbed Water on Methane Adsorption Capacity in Shale-Gas Systems

Frontiers in Earth Science

Zhenxue Jiang¹  Lei Chen²  Jingqiang Tan³  Song Guo⁴  Shu Jiang⁷ 

[1] Geoscience Institute, University of Utah, Salt Lake City, UT, United States;;Energy &Energy Department of CNPC Greatwall Drilling Company, Beijing, China;Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, China University of Geosciences, Wuhan, China;School of Geosciences, China University of Petroleum (East China), Qingdao, China;Shandong Provincial Key Laboratory of Deep Oil and Gas, Qingdao, China;State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, China;

关键词: shale gas;    pre-adsorbed water;    methane adsorption;    relative humidity;    water saturation;   

DOI  :  10.3389/feart.2021.757705

来源: DOAJ

【 摘 要 】

The presence and content of water will certainly affect the gas adsorption capacity of shale and the evaluation of shale gas content. In order to reasonably evaluate the gas adsorption capacity of shale under actual reservoir conditions, the effect of water on methane adsorption capacity needs to be investigated. Taking the Da’anzhai Member of the Lower Jurassic Ziliujing Formation in the northeastern Sichuan Basin, China as an example, this study attempts to reveal the effect of pre-adsorbed water on methane adsorption capacity in shale-gas systems by conducting methane adsorption experiments in two sequences, firstly at different temperatures under dry condition and secondly at different relative humidity levels under the same temperature. The results show that temperature and relative humidity (i.e., water saturation) are the main factors affecting the methane adsorption capacity of shale for a single sample. The key findings of this study include: 1) Methane adsorption capacity of shale first increases then decreases with depth, reaching a peak at about 1,600–2,400 m. 2) Lower relative humidity correlates to greater maximum methane adsorption capacity and greater depth to reach the maximum methane adsorption capacity. 3) 20% increase of relative humidity results in roughly 10% reduction of maximum methane adsorption capacity. As a conclusion, methane adsorption capacity of shale is predominately affected by water saturation, pore type and pore size of shale. This study could provide a theoretical basis for the establishment of a reasonable evaluation method for shale adsorbed gas content.

【 授权许可】

Unknown