Novel preformed gel particles with controllable density and its implications for EOR in fractured-vuggy carbonated reservoirs

Abstract

The pre-crosslinked gel particles has been perceived as an important alternative to improve oil recovery from fractured-vuggy carbonate reservoirs. However, it remains a great challenge for the applications in high temperature and high salinity reservoirs. In this context, we firstly developed novel preformed gel particles with controllable density (PGPCD) which can be used at high temperature (140 °C) and high salinity (250 g/L) fractured-vuggy carbonate reservoirs for in-depth profile control and displacement. Then, the swelling property, toughness, injectivity, EOR potential and EOR mechanisms of PGPCD were investigated. Experimental results show that PGPCD has favorable swelling ability, toughness, and controllable density due to the introduction of sodium montmorillonite and modified foamed acrylate rubber (ACM) powders. Moreover, PGPCD has favorable injectivity, and can mitigate water channeling in the form of “filling accumulation”, “bifurcation accumulation”, and “necked accumulation”. After the treatment, PGPCD achieves incremental oil recovery in a range of 16%–26% of original oil in place. Taken together, our findings suggest the role of PGPCD in promoting the incremental oil recovery at high temperature and high salinity reservoirs, especially in fractured-vuggy carbonate bottom water reservoirs.