Enhancing The Value of The Irong Barat Field through An Integrated Team Approach

Abstract

Irong Barat Field, located in the southeastern part of the Malay Basin, was discovered in 1979. The field structure is a complexly faulted WNW-ESE trending asymmetrical anticline dissected into four major fault blocks by a set of NNW- SSE trending normal faults, with additional subsidiary faults further segmenting the field in the central fault blocks. Oil bearing reservoirs are encountered in the H and I reservoir groups, with the bulk of reserves and present production from the H-50 unit. Existing development, 18 wells from a manned Irong Barat A platform, is mainly confined to the structurally less complex Fault Block I with 2 wells completed in the adjacent Fault Block II. Production started in November 1983 and more than 80% of the estimated developed reserves have been produced. Currently the field is producing at 11 MSTB/D. A multi-disciplinary team was formed to identify and mature the hydrocarbon potential of the complexly faulted undeveloped Fault Block II, III and IV and also the remaining opportunity in Fault Block I. The 3D seismic, appraisal well, production and well data were reviewed and a few development options were considered. As a result of the integrated field review, 2 additional drilling programs are planned to further develop the field, which involve drilling of 20 new wells from existing Irong Barat A and a new Irong Barat B platform. This paper discusses how the integrated field review enabled the team to further develop the field through better understanding of the reservoir and geology and better managing of the uncertainties. Introduction The Irong Barat oil field lies in the South China Sea about 184 km to the east of Kertih, Terengganu in a water depth of 60 m (Fig. 1). The field was discovered in 1979 and a total of 12 exploration wells were drilled to delineate the field over a period of 17 years. Irong Barat structure is a faulted asymmetrical anticline plunging to the west and is divided into four major fault blocks: Fault Blocks I (FBI), II (FBII), III (FBIII) and IV (FBIV) (Fig. 2 and 3). Irong Barat came on stream in November 1983 from Irong Barat A platform via 15 development wells. 13 wells were confined in FBI and 2 wells in the adjacent FBII (Fig. 4). The developed reservoirs are the H and I Groups with the H-50 unit containing 94% of the reserves. The oil production peaked at 23 MSTB/D in 1984. 3 additional infill wells were then drilled in late 1988 providing an incremental peak rate of 12 MSTB/D (Fig. 5). Currently the field is producing at 11 MSTB/D with an increasing gas oil ratio of 1000 Scf/Stb, and water cut of less than 10%. As of end of 1999, 106 MMSTB of oil or about 82% of the total developed field reserves have been produced. In order to identify and mature the hydrocarbon potential of the complexly faulted undeveloped, an integrated multi disciplinary team was formed with members from reservoir, geology, geophysics and drilling groups.