Oil Recovery From Thin Heavy-Oil Reservoirs: The Case of the Combined-Thermal-Drive Pilot in the Morgan Field

The Morgan field in Canada produces from the Lloydminster and Sparky sands, which are thin heavy-oil reservoirs. Early development of the pool was with primary vertical wells in the late 1970s, with some enhanced-oil-recovery (EOR) projects [e.g., cyclic-steam stimulations (CSSs) and in-situ combustion (ISC)] attempted in the early 1980s. However, the area was essentially noncommercial after the 1986 oil-price collapse. In order to regain commerciality, the operators implemented progressing cavity pumps (PCPs) and horizontal drilling, which have proved to be a success. Even with these advances, though, recovery is estimated to be less than 10% of the original oil in place (OOIP). One of the EOR projects attempted was the combined-thermal-drive (CTD) pilot, which was carried out in one of the sections of the field for 10 years. After a brief primary-production period, the CTD pilot began in 1980 and consisted of three stages. In the first stage, CSSs were performed on individual wells during the first 2 years. In the next 4 years, air was added to the injection stream to perform cyclic air/steam stimulations on individual wells. In the last stage, pressure cycling in-situ combustion was performed for approximately 4 years. In this paper, historical production and injection records were gathered to perform a technical and economic analysis of the project. After approximately 20 years since the shutdown of the project, the data indicate that this pilot has outperformed all of the other operations carried out in other areas of the field. Not only has it produced the largest amount of incremental oil of all the sections of the field, but it also managed to sustain high production rates for 10 years, which is unparalleled in the area. On the economic side, the data indicate that the project was experiencing difficulty because of the 1986 oil-price collapse. However, an economic analysis under current oil prices and costs suggests that it would have been both a technical and an economic success. This air-injection case history represents a good opportunity for those operators facing the challenge to develop thin heavy-oil reservoirs.