Integrated Regional Interpretation and New Insight on Petroleum System of South Sumatra Basin, Indonesia

Abstract

South Sumatra Basin is an inverted post-arc Tertiary basin, which has a complex evolution history from late Eocene-Oligocene extension to late Miocene and Pliocene compression. To evaluate the overall basin prospectivity, a regional analysis is conducted at 8 stratigraphic levels from pre-Tertiary unconformity to Pleistocene. An integrated interpretation including more than 1400 2D seismic lines, 4 seismic 3D surveys, and formation evaluation from 80 key wells is used to run the basin analysis. A series of regional seismic transects are defined through key wells and major structural elements to capture the characteristics of structural styles, lithostratigraphy and hydrocarbon distribution across the basin.Structural restorations unravels the timing of fault activity showing basin rifting until ~23 Ma with main depocenters in Benakat Gully, Limau Graben, Central Palembang and Lematang Depression followed by sagging until 14.6 Ma. The compressive event is recorded from 5 Ma to present day. The buckling of syn-rift sediments suggests shortening expressed by inversion and fault reactivation rather than thrusting. Review of the source rock data, reservoir distribution, hydrocarbon phase and source to reservoir correlation data are evaluated in perspective of the basin configuration in order to select sections for basin modeling. The modeling results show onset of expulsion varying from ~10-15 Ma from Lemat Fm. and Talangakar Fm., and 5 Ma from Telisa Fm. Modeling suggests that Talangakar Fm. reservoirs are completely filled, whereas Lemat Fm. reservoirs are partially filled due to limited lateral and downward migration. Baturaja Fm. reservoirs in proximity to depressions are filled, and partial charge risk away from kitchen area. Most of the hydrocarbon are generated, expelled and accumulated between sedimentation of Lower Palembang Fm. to inversion time (10-5 Ma). The subsequent inversion is likely to have re-migrated hydrocarbon in Talangakar and Baturaja reservoirs along Benakat Gulley and associated fault bound folds.

Pleistocene Accelerated Exhumation Within the Sumatran Fault: Implications for Late Cenozoic Evolution of Sumatra (Indonesia)

“…First, coarse clastic sediments from Sumatra were deposited offshore in the forearc basin at ∼10 Ma, and fluvial drainage on Sumatra was predominately east-flowing prior to the Pliocene, and only switched to westward flow later (Cameron et al, 1980;Harbury & Kallagher, 1991;Karig et al, 1979). Second, the transpressional deformation occurred in the last 5 Myr or earlier, which produced large-scale folds in the major basins of Sumatra, including the Ombilin and the North, Central, and South Sumatra basins, and may have affected the Barisan Mountains (Figure 2a; e.g., Barber et al, 2005;Carrillat et al, 2013;Zaim et al, 2012). Third, paleogeographic reconstructions of SE Asia incorporating basin data, particularly palynology by Morley et al (2016) and R. J.…”

Hydrocarbon Columns of Oil and Gas Fields in the South Sumatra Basin

“…Many authors have discussed the petroleum system of this basin (e.g. Argakoesoemah & Kamal, 2004;Bishop, 2000;Carrillat et al, 2013;Clure, 2005;Ginger & Fielding, 2005) and they are useful for providing regional geological perspectives. The oil and gas fields in South Sumatra are usually discussed independently by the operators (e.g.…”

“…The oil and gas fields in South Sumatra are usually discussed independently by the operators (e.g. Carrillat et al, 2013;Chalik et al, 2004;Lu et al, 2005;Suta & Utomo, 2006). Different seismic vintages, density and quality make seismic correlations across the basin challenging.…”