Glenn Pool Surfactant Flood Pilot Test: Part 2—Field Operations

Abstract

Summary A surfactant flood pilot test was conducted in a 20-acre [8.1 -ha], four inverted five-spot pattern in the Glenn Pool field. The field had been waterflooded and the pay zone, the Upper sand, was at a depth of 1,500 ft [457 m]. The crude oil had a viscosity of 4.0 cp [4 mPa-s] at a reservoir temperature of 95°F [35°C]. The process consisted of sequential injection of 35% PV of preflush, 10% PV of sulfonate slug, and 35% PV of polymer solution, followed by drive water. Injection operation was smooth; no injection well plugging was observed during sulfonate and polymer solution injection. On the other hand, production operation was somewhat hampered by plugging of producers. Low-equivalent-weight sulfonate precipitated out around the producers and contributed to the plugging problem. Solvent treatment corrected this situation effectively. Although a large oil bank was observed in the two observation wells and all other observation-well behavior indicated a successful process performance, the total oil production was disappointing. About 63,000 bbl [104 m3] of incremental oil was produced. During the test, it was established through reinterpretation of existing data and a pulse test program that there was no clear separation between the Upper and Middle sands. The impermeable shale streaks separating these two zones were not continuous. The implication was that injected fluids were not confined in the Upper sand. This made the interpretation of field data very difficult.