Second Successful Wettability Altering Surfactant (WAS) EOR Pilot in a Middle-Eastern Offshore Carbonate Field

Historically, surfactant EOR has been associated with IFT reduction, this process requires continuous surfactant injection and is a reversible phenomenon. NOC undertook an extensive lab program to identify and evaluate surfactants that would permanently alter the formation wettability from oil to water wet, using low concentration and low pore volume injection. Lab studies de-risked the path for an injectivity test which paved the way for a first field pilot in 2019. Production data analysis from the first pilot has shown a sustained increase in oil rate. There was little to no impact in terms of injectivity or injected water volume. After the success of the first Pilot, a second pilot was proposed to de-risk the application of this EOR technique in a different sub-surface environment as a precursor to commercial deployment. During the second pilot, water injectivity and absolute water injection rates increased very quickly, by the end of 6 months of surfactant injection a 10–12% jump in injectivity index was seen in both injectors which translated to 800–1000 bbl/d of extra injected water. On production side, the central producer receiving two-sided surfactant impact has seen a 20% rise in oil rate above baseline with 6–9% reduction in water cut