Design, Implementation and Early Operating Results of Steam Injection Pilot in already CO₂ Flooded Deep-Heavy Oil Fractured Carbonate Reservoir of Bati Raman Field, Turkey

With initial heavy-oil in place of 1.85 billion barrels, the Bati Raman Field (Turkey's largest oil deposition) was discovered and put on stream in 1961. The field hardly attained a primary recovery of ~2% due to the poor quality of the rock and fluid properties, and a low energy drive mechanism. An immiscible carbondioxide (CO₂) flooding project commenced in 1986 and it has been successfully implemented for about a quarter of a century. Oil production, which was only 1,500 STB/D prior to this project, reached 14,000 STB/D within a few years, however, there has been a declining trend thereafter.

The project is still active and has added significant value to the field showing an increment of 3-4 times in the recovery factor. Nevertheless, the amount of CO₂ required for one extra barrel of oil has a tendency to increase and the fact that the CO₂ injection will soon complete its mission, remaining a considerably high amount of oil in the reservoir. Therefore, there is great incentive to implement another effective enhanced recovery process in the field to drain this remaining oil.

Currently, the field is under consideration for another marginal and unique application of enhanced oil recovery, of which no analogous application is yet known worldwide. A steam injection pilot in already CO₂ flooded deep-heavy oil fractured carbonate reservoir has been initiated. There are a few similar applications, but their depths are incomparably shallower than the Bati Raman Field. The steam injection pilot with two injectors, one observer, and eleven producers at the crest was commenced in September 2012. The purpose was to heat and pressurize the reservoir from the top and produce oil from the neighboring producers. This paper documents the design, implementation, and early operational results of this pilot project.