--> Abstract: Paleomorphology and Reservoir Architecture of Tertiary Post-Rift Depositional Forms, from the Framework, Facies Classification, to the Reservoir Scale Geometry: A Case Study in Central Sumatra, Indonesia, by Erlangga Septama, Yudi Yugantoro, Albert Suwandy, Yosi Hirosiadi, and Bob W. H. Adibrata; #90039 (2005)

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Paleomorphology and Reservoir Architecture of Tertiary Post-Rift Depositional Forms, from the Framework, Facies Classification, to the Reservoir Scale Geometry: A Case Study in Central Sumatra, Indonesia

Erlangga Septama1, Yudi Yugantoro2, Albert Suwandy3, Yosi Hirosiadi4, and Bob W. H. Adibrata5
1 PT. Pertamina (Persero), Jambi, Indonesia
2 PT. Pertamina (Persero),
3 PT. Pertamina (Persero), Indonesia
4 Pertamina Upstream, Jakarta, Indonesia
5 Pertamina Upstream, Indonesia

The stratigraphic signatures of sedimentary rocks are poutpori of interaction of tectono-eustatic, sedimentation, biogenic and climatic, which preserved as facies relic, and Paleomorphology reconstruction on seismic stratal-slice is possibly the best method to recognize them. This study focused on Tertiary postrift deposits of Central Sumatra pull-apart basin, which have a superb continuity, moderate layer thickness and significant thickening indicate sagging during the depositional.

This presentation summarizes the interpretation of two 3D seismic volumes, Bulian and Ketaling block, which involved (#1)the conventional-seismic texture pattern recognition, (#2)querry of favourable seismic attributes (supervised and unsupervised multi-attribute classification) and (#3)waveform classification, where each method has a unique approach for particular facies. Five major horizons were extracted from so-called transgressive Gumai formation (early-middle Miocene), and revealed marine bar, fluvial channel, flood plain, splays, and slope deposits (transgressive ?).

The facies classification of each horizon slice then upscale as a framework to build reservoir netsand geometry. Procedures such as seismic inversion, and 2D AVO combined with well data, (RFT, log and production) in turn used to support the correct interpretation in reservoir properties and fluid detection. The results shows (1) the paleo-topography remains act as a main depositional control even in postrift stages, (2)there is a strong dependecies of particular facies with the hydrocarbon generation (the marine bar tend to correspond to oil-prone while channel features more potential as a gas-prone reservoir). The reserve calculation of which the moderate oil and gas fields are found, draw 270 bscf of GIIP and 24 MMSTB of OIIP.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005