Publications

Since 1977, Elf Aquitaine has gathered a lot of experience on chemical oil recovery on the Chateaurenard field (France). The reservoir is composed of three horizontal sand layers with fresh water and rather thick oil.In 1977 a polymer flood has been initiated on a very large seven spot pattern. The polymer slug was composed of polyacrylamides supplied in emulsion form and dissolved in field water, it has already been injected and is now being displaced in the field by chase water. On three of the South wells a sharp increase of the oil production has been observed.At the beginning of 1978 we started a research surfactant pilot (the Method Pilot): 964 m3 of microemulsion were injected in a 100 m square inverted five spot which delineated a pore volume of 10,000 m 3.The microemulsion was displaced in the formation by a concentrated poly- acrylamide solution, followed by water. The arrival of an oil bank very well defined was observed shortly after microemulsion injection. At the end of the operation 73% of the original oil in place was recovered, compared to 43% expected after water flooding.Following the technical success of the Method Pilot, Elf Aquitaine has initiated a pilot test at an industrial scale on a four adjacent five spot configuration, at field spacing. The amount of chemicals injected has been reduced and fully automatized facilities have been put to operate.The operation is now half completed, oil production is proceeding according to the expectations.From an economic analysis of the operations, we deduced that, with the particular cost structure associated with the operation of this field, the cost of tertiary oil is about 16 dollars/bahel for polymer recovery and 40 dollars/ barrel for micellar recovery.