Encouraging Chemical EOR Field Results: First Multi-Well ASP Flooding Pilot Project in a Carbonate Reservoir Worldwide

Abstract

Abstract Alkaline-Surfactant-Polymer Flooding (ASP) has the potential to unlock massive oil reserves in quest of production sustenance within the bounds of profitable economics. Field results from a successful ASP pilot targeting the massive Sabriyah Mauddud (SAMA) reservoir in Kuwait, using a regular five-spot with five acre-spacing are encouraging. Oil cut post softened water pre-flushing reached 0% and tracer data indicated pre-mature breakthrough at the central producer. This necessitated in-depth conformance gel treatment1-3 to induce flow under matrix conditions and softened water injection resumed thereafter for a period of ~3 months, during which oil cut ranged between 2 to 6%. Oil cut then decreased to 0% again, beyond which polymer pre-flushing was introduced for a period of ~2 months, during which oil cut was increased to up to ~4%. ASP flooding resulted in an unambiguous and sustainable increase in oil cut with an average of ~12% over a period of more than 6 months. Furthermore, daily oil production rate after ASP flooding more than doubled. Effective oil-water separation of produced emulsion has been established and maintained using fit-for-purpose pre-heating, chemical dosing and gravity segregation technologies, thus resulting in relatively low BS&W levels in separated oil (i.e., <5%). Potential in-situ scale risks were effectively managed by injection an innovative scale inhibition package composed of inhibited glacial acetic acid in conjunction with a phosphonate-polymeric scale inhibitor into the capillary tubing string of the central producer, during which 100% production uptime was achieved for several months3. Field data demonstrated that in-situ scale risks due to ASP injection were originally overstated because scale issues were limited even without injecting the adopted scale inhibition package. ASP reservoir simulation forecasts indicate that oil rates and oil cut should continue to increase. ASP flooding is ongoing to date and continues to generate important operational learnings and priceless field data to evaluate the techno-economic viability of phased ASP flooding commercial development.