Determining the Influence of Supercritical CO2 on the Formation Sensitivity of Tight Sandstone

Abstract

To solve the problem of water-based fracture fluid is difficult to flow back in low-pressure gas reservoirs. Supercritical CO2 is facility to the fracturing flowback in low-pressure tight sandstone, and considered to be a new type of non-aqueous fracturing technology with broad application prospects. In order to study the feasibility of supercritical CO2 fracturing with low pressure tight sandstone. Studies at home and abroad have proved that supercritical CO2 fracturing is the key to the development of unconventional natural gas reservoirs, which has incomparable advantages over conventional hydraulic fracturing. To evaluation the influence of supercritical CO2 on the formation sensitivity of sandstone reservoir, the tight sandstone cores from jinqiu Gas field, Sichuan Basin were used, supercritical CO2 was used to interact with tight sandstone samples under formation condition, and then the changes of velocity sensitivity, water sensitivity, salinity sensitivity, alkaline sensitivity, acid sensitivity of tight sandstone were observed. After the interaction between tight sandstone and supercritical CO2, velocity sensitivity damage decrease 6.0%, water sensitivity damage decrease 11.5%, salinity sensitivity damage decrease 16.0%, alkaline sensitivity damage decrease 0.5%, acid sensitivity damage decrease 17.5%. This finding is quantitative evaluation of the impact of supercritical CO2 on formation sensitivity, and can provide scientific guidance for the development scheme of supercritical CO2 fracturing of low-pressure water sensitive tight sandstone.