Improving Oil Recovery from Carbonate Rocks Using Compositionally Modified Water Injection

There is a potential to improve oil production from carbonate and sandstone reservoirs by modifying the salinity and ionic composition of the injection brine relative to resident brine. This process can increase oil production in both green and mature water flooded reservoirs in secondary and tertiary modes. Although the use of low salinity water as an enhanced oil recovery fluid has been verified in the lab and field scales, extensive research is still underway to fully understand the physiochemical mechanisms responsible for increased oil recovery for different oil composition, reservoir temperature, and rock mineralogy. While initial studies focused mainly on sandstones, the fact that carbonate formations host a major portion of the world’s known oil reserves has motivated researchers to examine the feasibility of low salinity water injection in carbonates.