Influence of CO 2 -brine-rock Interactions on the Physical Properties of Tight Sandstone Cores via Nuclear Magnetic Resonance

• Published in: IOP conference series. Earth and environmental science 2021-10, Vol.898 (1), p.12021
• Main Authors: Liu, Hanbin, Li, Chengzheng, Zhao, Zhenfeng, Wang, Guangtao, Li, Changheng, Zhao, Jinsheng
• Format: Article
• Language: English
• ISSN: 1755-1307; 1755-1315
• DOI: 10.1088/1755-1315/898/1/012021

For sandstone reservoirs with extra-low permeability, CO 2 injection is regarded as a valid method to enhance oil recovery. When CO 2 injection is implemented in such reservoirs, the physical properties of the formation could be altered owing to the interactions between CO 2 , water, and rock. In this study, the influence of CO 2 –brine–rock interactions on the physical properties of tight sandstone cores was analyzed by comparing the obtained T 2 spectrum before and after CO 2 injection. The results revealed that the T 2 spectrum after CO 2 injection was significantly different from the original T 2 spectrum. CO 2 injection changed the pore size distribution of the core samples. When the injection pressure was low, the pore volume decreased from micropores to macropores leading to a decrease in both permeability and porosity. As the injection pressure increasing, the dissolution of CO 2 in the micropores was enhanced thus improving the pore-throat connectivity; which ultimately improved the reservoir physical properties.