Critical review of field EOR projects in shale and tight reservoirs

Field tests of different methods are reviewed and analyzed. It is shown that water injection has been applied in large scale field projects in tight formations and proved successful in China. CO2 injection has been tested many times in small scales in China. Several gas injection and water injection have been tested in US and Canadian shale reservoirs. Detailed results of those projects have not been reported, with test benefits mixed. Although surfactants are added in fracturing fluids to improve oil recovery performance, the mechanisms are not well understood.