Enhanced Wettability Modification and CO₂ Solubility Effect by Carbonated Low Salinity Water Injection in Carbonate Reservoirs

Abstract

Carbonated water injection (CWI) induces oil swelling and viscosity reduction. Another advantage of this technique is that CO 2 can be stored via solubility trapping. The CO 2 solubility of brine is a key factor that determines the extent of these effects. The solubility is sensitive to pressure, temperature, and salinity. The salting-out phenomenon makes low saline brine a favorable condition for solubilizing CO 2 into brine, thus enabling the brine to deliver more CO 2 into reservoirs. In addition, low saline water injection (LSWI) can modify wettability and enhance oil recovery in carbonate reservoirs. The high CO 2 solubility potential and wettability modification effect motivate the deployment of hybrid carbonated low salinity water injection (CLSWI). Reliable evaluation should consider geochemical reactions, which determine CO 2 solubility and wettability modification, in brine/oil/rock systems. In this study, CLSWI was modeled with geochemical reactions, and oil production and CO 2 storage were evaluated. In core and pilot systems, CLSWI increased oil recovery by up to 9% and 15%, respectively, and CO 2 storage until oil recovery by up to 24% and 45%, respectively, compared to CWI. The CLSWI also improved injectivity by up to 31% in a pilot system. This study demonstrates that CLSWI is a promising water-based hybrid EOR (enhanced oil recovery).

Carbonated Water Injection for Enhanced Oil Recovery and CO2 Geosequestration in Different CO2 Repositories: A Review of Physicochemical Processes and Recent Advances

“…19,111,145,146 A substantial increase in injectivity ranging from 35% to 170% was achieved from a simulation study. 145 Lee et al 146 also observed that carbonated low-salinity water flooding improved the relative injectivity of low-salinity water flooding (LSWF) from 0.83 to 0.86. In contrast, various permeability declines have been reported (Table 7).…”

“…Conversely, injectivity loss would engender insufficient CW injection pressure compared to reservoir pressure which could consequently lead to production decline or halt . A cluster of studies has underscored that CWI improves the injectivity of injection wells, which promotes oil recovery and efficient CO 2 storage in oil reservoirs. ,,, A substantial increase in injectivity ranging from 35% to 170% was achieved from a simulation study . Lee et al also observed that carbonated low-salinity water flooding improved the relative injectivity of low-salinity water flooding (LSWF) from 0.83 to 0.86.…”