Pungut Field is located in the CPI Rokan block, Central Sumatra Basin, approximately 60 km northwest of Pekanbaru, Indonesia. The field was discovered in 1951 and to date 39 wells, both producers and injectors, have been drilled in Pungut structure. Oil is contained in the Miocene-age reservoirs of the BKS and BKO Formations with 202 MMBO of reserves. The current oil production rate is 2,300 BOPD with water injection of 16,000 BWIPD. The BKS Formation is recognized as multilayer and heterogeneous reservoirs, characterized by their facies changing and properties distribution. As the size of the field indicates, declining reservoir pressure prompted an initial evaluation focusing on waterflood potential. However, a typical waterflood facility
design would require an extensive capital cost. In order to manage the non-uniform reservoir nature characteristics, heterogeneity and anisotropy with respect to further the waterflooding scheme, G&G study suggested to cluster the field vertically and areally as well. Thorough assessment, by taking the subsurface and surface facilities concerns into account, then recommended a two-staged project. The first stage would comprise injection/producer well pairs and dual-completed injection wells in peripheral injection points in the heterogeneous area or sand of the field. The second stage of the project would implement a full-field operation and drilling additional wells to improve the aerial sweep efficiency. This method also proved to be the most cost-effective alternative. Results to date have been good in term of capital, execution and production. Capital expenditure for stage 1 was only US$ 1.6 million with four month of execution while oil production has increasing significantly was from 1,600 BOPD to 2,300 BOPD. As the plan of field development is an active document, a slight modification has been made during the course of the project. After incorporating the latest project-based knowledge of reservoir zones compartmentalization into the 3D reservoir models, an adjustment in the plan including well placement and reservoir target was made.
Authors : Rd. Rai Raya Barkah, A. Rudiyono, Hasyim M. Nur, Mark R. Reinhold