Coupling of Low-Salinity Water Flooding and Steam Flooding for Sandstone Unconventional Oil Reservoirs

Abstract

In this study, we combined low-salinity (LS) water and steam as a novel enhanced oil recovery (EOR) method that can provide additional oil recovery up to 63% of original heavy oil in place, which is a very promising percentage. The LS water flooding and steam flooding are two novel combination flooding methods that were combined due to the significant effect of both methods in reducing residual oil saturation (especially heavy oil). The laboratory observations of LS water have been conducted by laboratory and pilot tests, which indicated that LS water could increase recovery to 41% of original oil in place. The thermal aspects provided by steam flooding enhanced heavy oil recovery in many field projects. Although the steam provided additional heavy oil recovery, the density difference between injected steam and in situ heavy oil raised badly behaved displacement issues. The problems could be steam channeling, gravity override, and early breakthrough. In view of that, we developed the low-salinity alternating steam flood (LSASF) to gather the benefits of LS water (altering sandstone wettability), reduce oil viscosity by steam, and prevent the steam problems mentioned earlier. Contact angle measurements showed that flooding the core using LSASF method resulted in more water wetness to the sandstone cores. Many scenarios were conducted experimentally, and the laboratory experiments showed that the optimum setup was reducing the injected LS steam cycles. The shorter the injected cycles are, the more the oil recovery is.