Water–rock–CO 2 interactions and CO 2 storage of Honghe tight oil reservoirs: an experimental and simulation study

CO 2 flooding is essential for significantly enhancing oil recoveries and long‐term CO 2 storage. We performed CO 2 flooding experiments on target tight cores obtained from Honghe oilfield to investigate the water–rock interaction during CO 2 flooding. In addition, we investigate the impact of mineralization and CO 2 injection patterns on the sweep efficiency and CO 2 long‐term storage using numerical simulations. Results show target core samples are composed of calcite, quartz, Na‐feldspar, and K‐feldspar. In particular, the main water–rock interactions during CO 2 flooding are calcite and Na‐feldspar dissolution. The impact of water–rock interactions on the reformation of the matrix is not significant. However, such water–rock interactions will decrease the permeability of the natural fracture system near injection wells, which will lead to the enhancement of CO 2 flooding efficiency in fractured formations. In addition, results show that water alternating gas injection will enhance oil recovery and CO 2 primary storage. After CO 2 flooding, mineral‐trapped CO 2 is only 0.53wt.% of the total CO 2 storage. As the flooding time increases, the mineral‐trapped CO 2 increases. Results show that mineral‐trapped CO 2 is 31.08% of the total CO 2 storage at the simulation time of 500 years. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.