ABSTRACT: The Geology of the Duri Field--Central Sumatra, Indonesia
HUNTER, WILLIAM A., and HARRY J. TAPIHEROE*, No Affiliation Given
The Duri Field, operated by PT Caltex Pacific Indonesia, under a production sharing contract with Pertamina, is located in Riau Province, Central Sumatra, about 120 km northwest of the city of Pekanbaru. It is the second largest oil field in Indonesia. The field is approximately 18 km long by 18 km wide. Due to the highly viscous nature of the hydrocarbon encountered at Duri, continuous stream injection is utilized to facilitate recovery. Duri is the largest project of its kind in the world.
Structurally, the Duri field is a faulted, asymmetric anticline with a north-south trend. It's bounded on the west by the right-lateral Sebanga fault which shows approximately 350 m of vertical displacement. Structural complexity is more pronounced in this part of the field due to the influence of this wrench system. The intensity of faulting diminishes to the east where the structure is more homoclinal and the dips average less than 3 degrees .
Depositionally, the type of sediments encountered in Duri field consist of tidal flat sands or reworked tidal estuarine channels with intertidal and/or subtidal muds. These sediments are common to the delta front zone of a tidally dominated delta complex.
Stratigraphically, the sediments of the early Miocene age Sihapas group (Duri and Bekasap Formations) comprise the main reservoir units within the Duri formation and consist of the 140 and 240 foot sands and the Rindu sands. Within the Bekasap Formation, the primary reservoir units consist of the Pertama and Kedua sands. The Pertama and Kedua sands are the most prolific producing zones.
Continuous steam injection has been used to enhance oil recovery since 1985. About 25% of the field has been developed using 5 and 7 spot pattern configurations. The 7 spot pattern configuration (1 injection well surrounded by 6 producing wells on 11-5/8 acre spacing) is predominant.
AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)