This paper is a review of the field development plan for the Jerneh gas field, located offshore east of Peninsular Malaysia. The major design steps in the development process are discussed which include gathering of required geological and reservoir data from delineation wells and subsequent studies to evaluate reservoir performance, production and processing facilities. The result of these studies is a development plan which incorporates forty wells and two producing platforms.
Jerneh is a non-associated gas field located 265 km off the east coast of Peninsular Malaysia in the South China Sea, at a water depth of 55 m (Figure 1). Esso Production Malaysia Inc. (EPMI) discovered the field in 1969 and will be developing it as a contractor to Petroliam Nasional Berhad (PETRONAS), the Malaysian national oil company.
The Jerneh field consists of a series of vertically stacked sandstones deposited in a lower coastal plain environment. The structure is a large anticline with an areal closure of 62 km2 at the gas-water-contact of the major E-50 sandstone. A total of eleven gas-bearing sandstones are planned for development at Jerneh. The reservoirs are found at depths ranging from 1200 to 2100 m.
The quality of the reservoir rock is generally fair to good. Porosities and permeabilities of individual sandstones range from 15 to 25 percent and 0.005 to 0.5 um2. Net gas sandstone thicknesses range from 5 to 30 m. The Jerneh gas compositions are relatively lean and have a low non-hydrocarbon content. The average carbon dioxide and hydrogen sulphide concentrations are 4 percent and 5 ppm respectively (Table 1).
The Jerneh field is currently planned for development with 40 wells drilled from two platforms. These two platforms will also contain gas processing facilities. A third platform will house central gas compression facilities. The platform installations will be staged as required to meet the gas demand. The overall facilities will be designed to process 21 std M.m3/d.
Initial individual well production rates vary from 0.3 to 1.4 std M.m3/d. Tubing sizes will be a combination of 139.7 mm in single wells and 88.9 mm in dual wells. Separate pipelines will be installed to transport the gas and condensate to shore.
A total of six exploration wells were drilled at Jerneh to adequately delineate the field. Figure 2 shows the position of these wells on the structure of the Jerneh E-50 sandstone. Jerneh 1A, 2 and 3 were drilled prior to 1975 and found gas in the groups D, E and F reservoirs of late Miocene age. Jerneh Barat 1 was drilled in 1979 to test hydrocarbon potential in the west fault block, and found gas in only one sandstone, the E-90. The rest of the D and E reservoirs were found to be water-bearing in this fault block and therefore this area is not planned for development. Two additional delineation wells, Jerneh 4 and 5, were drilled in 1985 to further evaluate the main part of the field.
Gas-water contacts were established in many of the reservoirs with others estimated from pressure data, fault leak points, and from high proved water and low proved gas data.
Groups D and E sandstones are interpreted to have been deposited in a lower coastal plain environment and are mostly tidal with some deltaic deposits. Two of the major reservoirs, the D-32 and E-50, are expected to have fairly good lateral and vertical continuity, while the other smaller reservoirs are expected to have poor to fair continuity.