Abstract

The rantau waterflooding project has been operated in Pertamina's Rantau oil field, North Sumatra, based on the 'Service Contract for Secondary Recovery' between Pertamina and Japex of 1979. As the field is a very old field that was discovered in 1929 by Royal Dutch Shell, the objective reservoirs were almost depleted at the time of the commencement of this project. After prudent engineering studies, 76 new wells were drilled in the objective area and a water injection operation was commenced through 57 injection wells (63 strings) into 3 target zones in May 1984. The injection water is treated sea water which is transferred from the mouth of the Serang Jaya river through a 12" pipe line.

As of May 1987, a total quantity of 6.3 million m³ water had been injected into the objective zones.

According to a simulation study executed in the last year, this waterflooding operation is expected to improve the recovery factor of the zones by more than 8%.