John B. Dunham¹, L. Douglas McKee²

(1) Unocal Indonesia Company, Balikpapan, Indonesia
(2) Unocal Indonesia Co, Balikpapan

ABSTRACT: Emergence of the Ganal Gas Trend - Deep Water Kutei Basin, Indonesia

Initial exploration on the Ganal PSC, located in the Deep Water Kutei Basin of Indonesia, focused on interpretation of a 2 x 2 km. grid of 2D seismic data. This coarse grid revealed numerous large anticlines at 4500' to 7000' water depth. Since it was known that abundant Pliocene and Miocene sand existed on the Kutei shelf, it was interpreted that significant sand should have been deposited in the basin during Miocene lowstands. Potential reservoirs were envisioned as base-of-slope and basin-floor fans. Traps were four-way structural closures. Hydrocarbon charge was predicted along deep-penetrating faults, sourced from terrestrial kerogen carried into the basin by turbidity currents, with top seals formed by a thick hemipelagic claystone sequence. Well locations were chosen directly from the 2D seismic grid, with the idea that the 2D grid was sufficient to define structural closures. If sand were present in the closures, then 3D would be acquired to delineate and develop any discoveries. In fact, excellent reservoir-quality gas sands were discovered in several Ganal anticlines. 3D seismic data subsequently acquired over the Gendalo discovery shows a large unconfined submarine fan covering at least 9000 acres, with an internal architecture of broad laterally continuous sheet sands. Continuity in the fan is demonstrated by MDT pressure data that show pressure communication between two Gendalo wells separated by a distance of 3.7 kilometers. Additional gas discoveries in the Gandang, Gula, and Gada structures are also in sheet sands. Reserves for the Ganal Gas trend are in the multiple TCF range.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado