Experimental Study on the Distribution Characteristics of CO 2 in Methane Hydrate-Bearing Sediment during CH 4 /CO 2 Replacement

CH 4 /CO 2 replacement is of great significance for the exploitation of natural gas hydrate resources and CO 2 storage. The feasibility of this method relies on our understanding of the CH 4 /CO 2 replacement efficiency and mechanism. In this study, CH 4 /CO 2 replacement experiments were carried ou...

Full description

Bibliographic Details
Published in:Energies
Main Authors: Jianye Sun, Xiluo Hao, Chengfeng Li, Nengyou Wu, Qiang Chen, Changling Liu, Yanlong Li, Qingguo Meng, Li Huang, Qingtao Bu
Format: Article in Journal/Newspaper
Language:English
Published: MDPI AG 2022
Subjects:
CH 4 /CO 2 replacement
gas hydrate
distribution characteristics
Technology
T
Methane hydrate
Online Access:https://doi.org/10.3390/en15155634
https://doaj.org/article/363d689a66f4435a97103b2c492bf1fc
Description
Summary:CH 4 /CO 2 replacement is of great significance for the exploitation of natural gas hydrate resources and CO 2 storage. The feasibility of this method relies on our understanding of the CH 4 /CO 2 replacement efficiency and mechanism. In this study, CH 4 /CO 2 replacement experiments were carried out to study the distribution characteristics of CH 4 and CO 2 in hydrate-bearing sediments during and after replacement. Similar to previously reported data, our experiments also implied that the CH 4 /CO 2 replacement process could be divided into two stages: fast reaction and slow reaction, representing CH 4 /CO 2 replacement in the hydrate-gas interface and bidirectional CH 4 /CO 2 diffusion caused replacement, respectively. After replacement, the CO 2 content gradually decreased, and the methane content gradually increased with the increase of sediment depth. Higher replacement percentage can be achieved with higher replacement temperature and lower initial saturation of methane hydrate. Based on the calculation of CO 2 consumption amounts, it was found that the replacement mainly took place in the fast reaction stage while the formation of CO 2 hydrate by gaseous CO 2 and water almost runs through the whole experimental process. Thus, the pore scale CH 4 /CO 2 replacement process in sediments can be summarized in the following steps: CO 2 injection, CO 2 diffusing into sedimentary layer, occurrence of CH 4 /CO 2 replacement and CO 2 hydrate formation, wrapping of methane hydrate by mixed CH 4 -CO 2 hydrate, continuous CO 2 hydrate formation, and almost stagnant CH 4 /CO 2 replacement.

Similar Items