Abstract

An upper Pleistocene basin-floor fan was characterized from seismic data to provide analogs for reservoir elements in deep-water fields planned for development, including Gendalo gas field, offshore East Kalimantan, Indonesia. The Pleistocene basin-floor fan is approximately 170 m (550 ft) thick, about 22 km (13.6 mi) across, and contains 18 lobes. The average lobe size is 3.8 by 7.2 km (2.3 by 4.4 mi) with an average thickness of 34 m (111 ft). Lobes contain sheetlike splay elements, distributary channels, and younger incised channels. Lobes range from splay dominated to channel dominated. Splay elements are 400–1200 m (1312–3937 ft) wide, 500–3000 m (1640–9842 ft) long, and 4–13 m (13–42.6 ft) thick. Distributary channels have an average width of 161 m (528 ft), average thickness of 12.6 m (41.4 ft), and average length of 2.2 km (1.3 mi). Younger channels incising into older lobes have an average width of 392 m (1286 ft) and an average thickness of 13 m (42.6 ft).

The upper Miocene Gendalo 1020 reservoir is composed of turbidite sands draped over an anticline. The reservoir has been penetrated by four wells and is imaged by a three-dimensional seismic survey with a dominant frequency of 15–20 Hz in the reservoir interval. The gross reservoir interval is 50–150 m (165–500 ft) thick and contains thin-bedded turbidite sands with a net-to-gross of approximately 50%. Seismic attributes indicate a fan-like morphology. Sands occur in 9–40-m (29–130 ft)-thick packages interpreted as lobes. Lobes, 3.5 to 7.5 km (2.2 to 4.7 mi) across, were mapped seismically, which was consistent with the Pleistocene fan; however, the seismic data could not image intralobe features like channels and splays. Dimensions from Pleistocene channels and splays were used to stochastically model channels and splays within the Miocene fan lobes. Well test data and pressure data are consistent with the model.

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