Tailored injection water slug designs for enhanced oil recovery in carbonates

摘要

Provided are oil recovery compositions and processes for enhancing oil recovery from a carbonate reservoir. A process for enhancing oil recovery includes injecting a first slug of an aqueous solution having a salinity in the range of about 5,000 ppm TDS to about 7,000 ppm TDS and sulfate ions in the range of about 500 ppm to about 5000 ppm. After injection of the first slug, the process includes injecting a second slug of an aqueous solution having a salinity in the range of about 5,000 ppm TDS to about 7,000 ppm TDS, calcium ion concentrations in the range of about 100 ppm to about 1000 ppm, and magnesium ions in the range of about 200 ppm to about 2000 ppm. A third slug of seawater or produce water may then be injected as chase water.