CO 2 –Brine–rock interaction and sequestration capacity in carbonate reservoirs of the Tahe Oilfield, Xinjiang, China

• Published in: Greenhouse Gases: Science and Technology
• Main Authors: Tan, Yongsheng, Li, Qi, Xu, Liang, Xu, Lifeng, Yu, Tao, Cao, Xiaomin
• Other Authors: National Natural Science Foundation of China
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: Carbonic acid
• Online Access: http://dx.doi.org/10.1002/ghg.2178; https://onlinelibrary.wiley.com/doi/pdf/10.1002/ghg.2178; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/ghg.2178

Abstract The characteristics of each carbonate reservoir are greatly different, and current databases are insufficient to support engineering scheme design and optimization of carbon dioxide (CO 2 ) sequestration and enhanced oil recovery. In this paper, the behavior of CO 2 ‐brine‐rock interactions was investigated under supercritical CO 2 (50°C and 8.5 MPa) conditions. Five experiments were carried out, including CO 2 solubility in brine, mass loss analysis by static reaction of CO 2 –brine–rock, mineralogical composition analysis by X‐ray diffraction (XRD), core surface morphology analysis by scanning electron microscopy (SEM), and wettability alteration by contact angle analysis. The experimental results showed that: (a) the CO 2 solubility in brine increases with increasing pressure, but it increases slowly and gradually reaches equilibrium; (b) the mass loss of carbonate increases with reaction time, but its increments decrease with reaction time; (c) the calcite content gradually decreases and the quartz content slightly increases with reaction time, as evidenced by XRD analysis; (d) based on SEM image analysis, calcite was dissolved into brine by carbonic acid to make the pores larger, and then subsequent precipitation made the pores smaller; and (e) the carbonate rock surface became more water‐wet after CO 2 –brine–rock interaction experiments due to surface corrosion and increased quartz content. Using the experimental results, a mathematical model was developed to predict CO 2 sequestration capacity under reservoir conditions. The results suggest that CO 2 solubility in brine was the main aspect compared with mineral trapping in carbonate reservoirs, and CO 2 sequestration capacity increased with increasing temperature and pressure. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.