Simulation of Volcanic Minerals Dissolution in CO<sub>2</sub>-Aqueous Solutions under High Temperature and Pressure
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In order to study the effect of high-temperature and high-pressure CO2 on the physical properties of deep volcanic rock reservoirs in the southern Songliao Basin, a closed-system temperature and pressure co-controlled solution reaction simulation method was used to simulate formation temperatures (120°C, 130°C, 140°C) and formation pressures (20MPa, 40MPa, 60MPa) conditions, 12 groups of supercritical CO2-solution reaction experiments were carried out. The pore characteristics of the reservoir rock samples before and after the reaction were analyzed using QEMSCAN and scanning electron microscopy to determine the modification of reservoir properties and ionic changes in CO2-aqueous solutions due to the solution reaction after CO2 injection into deep volcanic reservoirs. The experimental results show that the solution reaction reaches equilibrium after 96 hours. Supercritical CO2 has different dissolution effects on rock samples at different temperatures and pressures, with a maximum dissolution rate of 0.2803g and a maximum increase in porosity of 5.18%. Supercritical CO2 dissolved in water forms an acidic environment that has a strong acid etching and remolding effect on rock samples, indicating that the high-temperature, high-pressure supercritical CO2-solution reaction is initially dominated by calcite dissolution, followed by dolomite and feldspar minerals dissolve slowly, and quartz minerals are not significantly altered. This experiment shows that selecting representative samples to carry out simulated solution reaction experiments under deep formation conditions is an effective and scientific reservoir modification method. In the current context of high cost, high risk, and high investment in deep oil and gas exploration, the results of the high temperature and high-pressure supercritical CO2-solution reaction experiment have essential reference value for the next step of deep reservoir exploration and development.