Mass Transfer Analysis of CO2-Water-Rock Geochemical Reactions in Reservoirs

It is difficult to exploit low-permeability reservoirs, and CO2 flooding an effective method improve oil recovery from low permeability reservoirs. However, in the process of flooding, acidic fluids dissolved formation water will react with rock cause dissolution precipitation, resulting pores precipitates, changing evolution law seepage channels, destroying integrity, affecting effect displacement. The change rock’s physical properties mass transfer between CO2-water-rock are unclear. This paper considers coupling effects seepage, mechanics, chemistry when injected into formation. model geochemical reaction established on this basis. reservoir after injection quantitatively studied based microscopic mechanism chemical reaction, migration solute during under multiple fields clarified. experimental results show that increase time, initial rocks be transformed a precipitation calcite, magnesite, clay minerals. porosity near well first then decrease. far end still dominated by reactions, average values upward trend. Although can certain extent, mutual transformation further exacerbates heterogeneity pore structure, leading instability migration, uneven displacement, destruction stability. research solve problem quantitative calculation parameters reservoirs predict changes properties, which provide theoretical basis for evaluating integrity adjusting condition flooding.