South China Sea

Collaborating Authors

South China Sea

Post Mortem of a Fast Track Subsea Oil Development

Guise, David R. (Gulf Indonesia Resources) | Chered, Norma Fitri (Gulf Indonesia Resources)

OnePetroApril, 2001

Abstract Jangkar-1X was drilled in the first quarter of 1998 and discovered oil and gas in five reservoirs in the Lower Gabus and Pasir Formations. The Jangkar Field is located in the Kakap PSC (Indonesia) and is part of the Wrench Fault Trend which has yielded significant rewards to the Kakap PSC partners. The well was not tested but open hole log evaluation, down hole fluid samples and pressure data confirmed the presence of oil and gas in highly porous and permeable sands. In response to this success, a fast track development plan was formulated which resulted in a second well, Jangkar-2X being drilled, completed and placed on production as a sub-sea oil producer prior to the end of 1998. This fast track development was the result of a strategic decision to pre-purchase the long delivery items required for sub-sea tie-ins in anticipation of a least one successful exploration well in a multi-well drilling program. This paper reviews the basis for the decision to pre-order inventory and documents the strategy and development plan which resulted in this well being placed on production within ten months of the field being discovered as well as the technical and commercial results of the project. Introduction The Jangkar Field is located in the Kakap PSC (Indonesia), four miles east of the KH Field and five miles west of the KG Field (Figure 1). The field was discovered in March 1998 by the Jangkar-1X exploration well and sidetracks (three mechanical sidetracks). The Jangkar-1X well was drilled to test a tilted fault block with mapped structural closure at numerous levels within the post-rift sequence, specifically the Pasir to Lower Gabus Formations. The Jangkar-1X well was suspended after encountering a stacked series of independent pay zones comprising the L1 Sand (Pasir Formation), L3 Sand (Barat Formation) L5, L49 and L50 Sands (Upper Gabus Formation) and a sand member within the Lower Gabus Formation (ILG-1 Sand). The L1, L3 and L49 Sands had gas caps associated with the oil legs. There was no evidence in the Jangkar-1X well for gas caps to the L5, L50 or ILG-1 Sands. Oil-Water-Contacts (OWC) were encountered in the L5 and ILG-1 Sands in the Jangkar-1X well. With the exception of the ILG-1 Sand, these reservoirs are also hydrocarbon bearing in the KH Field to the west where the L49 and L50 Sands are important oil pay zones with associated gas caps and the L1, L3 and L5 Sands are non-associated gas reservoirs. All have been produced for their oil reserves or for gas lift purposes. Differential pressure depletion was observed in the Jangkar-1X well as a direct result of production in the KH Field. It was planned to appraise the Jangkar-1X discovery with a second well Jangkar-2X. This well was located in the southern part of the structure in a slightly downdip location. The well has specific objectives at the L1 and L49 Sand levels. If successful it was planned to complete and tie-in one or both of the wells via a subsea pipeline to the KH Platform. Reservoir Description Structure The structural style of the Jangkar Field is illustrated by representative seismic dip (E-W) and strike (N-S) lines (Figures 2 and 3) and schematic cross-sections along the well tracks of both Jangkar-1X and Jangkar-2X (Figure 4).

OnePetro

doi: 10.2118/68738-MS

SPE

SPE-68738-MS

SPE Asia Pacific Oil and Gas Conference and Exhibition