Performance of free gases during the recovery enhancement of shale gas by CO_(2) injection:a case study on the depleted Wufeng–Longmaxi shale in northeastern Sichuan Basin,China  

作　　者：Jun Liu Ling-Zhi Xie Bo He Peng Zhao Huai-Yu Ding 

机构地区：[1]State Key Laboratory of Hydraulics and Mountain River Engineering,Institute of New Energy and Low-Carbon Technology,Sichuan University,Chengdu,610065,China [2]College of Architecture and Environment,Sichuan University,Chengdu,610065,China [3]Liaohe Oilfield Company,PetroChina,Panjin,124010,China

出　　处：《Petroleum Science》2021年第2期530-545,共16页石油科学（英文版）

基　　金：This study was financially supported by the National Natural Science Foundation of China(Grant Nos.51704197 and 11872258)。

摘　　要：In this work, a novel thermal–hydraulic–mechanical (THM) coupling model is developed, where the real geological parameters of the reservoir properties are embedded. Accordingly, nine schemes of CO_(2) injection well (IW) and CH_(4) production well (PW) are established, aiming to explore the behavior of free gases after CO_(2) is injected into the depleted Wufeng–Longmaxi shale. The results indicate the free CH4 or CO2 content in the shale fractures/matrix is invariably heterogeneous. The CO_(2) involvement facilitates the ratio of free CH_(4)/CO_(2) in the matrix to that in the fractures declines and tends to be stable with time. Different combinations of IW–PWs induce a difference in the ratio of the free CH4 to the free CO_(2), in the ratio of the free CH_(4)/CO_(2) in the matrix to that in the fractures, in the content of the recovered free CH_(4), and in the content of the trapped free CO_(2). Basically, when the IW locates at the bottom Wufeng–Longmaxi shale, a farther IW–PWs distance allows more CO2 in the free phase to be trapped;furthermore, no matter where the IW is, a shorter IW–PWs distance benefits by getting more CH_(4) in the free phase recovered from the depleted Wufeng–Longmaxi shale. Hopefully, this work is helpful in gaining knowledge about the shale-based CO_(2) injection technique.

关 键 词：CO_(2)geological sequestration Enhanced shale gas recovery Free gas Wufeng-Longmaxi Formation THM coupled modeling 

分 类 号：TE377[石油与天然气工程—油气田开发工程]