The Bakken is one of the most prolific plays in North America, but, even with the deployment of horizontal wells and hydraulic fracturing, anticipated recovery factors under primary depletion are usually in the range of 10 to 20%. Waterflooding has been a commonly deployed technology in conventional reservoirs to enhance recovery beyond primary depletion. However, the Bakken’s ultratight, largely oil-wet nature limits the potential of waterflooding. As an alternative, an optimally spaced well-to-well surfactant-flooding technology is proposed.
Introduction
Recent studies focusing on wettability alteration by use of surfactant in the Bakken have shown strong potential. Spontaneous-imbibition tests in Bakken cores show recovery factors that can exceed 30% and sometimes achieve up to 60%. However, in an ultralow-permeability system, the rate of surfactant imbibition is perhaps more important than the ultimate recovery factor.
