Print this pageTectonosedimentary Implications from the Petroleum System in and Around Andaman Basin, India
The Andaman basin is part of a large geotectonic unit that extends from Sumatra (Indonesian) Islands in the south to Myanmar (Burma) in the north, lying in Bay of Bengal. It consists of the Andaman-Nicobar chain of islands Major geotectonic units from east to west are back arc, volcanic arc, fore arc, Island arc and fore deep.
Significant hydrocarbon discoveries in this basin is yet to be established. However, important hydrocarbon indications in the Irrawady Delta to the north and in the North Sumatra Tertiary Basin towards south enhances the prospectivity of the area. Of the fourteen exploratory wells drilled in the western and eastern offshore parts of the Islands by the National Oil Companies of India, one indicated Hydrocarbon show while another drilled in the eastern offshore, produced gas from Miocene limestone.
Tectonically, the area can be divided into North and South Andaman Basin. The Martaban Canyon, along with the Irrawady Delta system is the principal sediment source for the North Andaman Basin, whereas Sumatra and Malaya orogen is the provenance for southern part until the Neogene time.
During Oligocene, rise of Andaman Island contributed coarser Flysch sediment towards west and east. Lithofacies distribution in Port Blair Formation indicate an increase of sand/ silt towards west of Andaman in Inner slope area and the carbonates may be the potential reservoir rocks. Baratang Formation is the principal source rock of the area. Deep seated faults may act as effective conduits for Thermogenic gas. Lower geothermal gradient (1.6 to 2.0 C/100m) suggest deeper oil window in the Andaman area. However, Paleogene sediments uplifted during Oligocene and coupled with igneous intrusion may have given maturity to source rock at shallower depth locally. Tectono-sedimentation studies indicate that various sub-basins have varying tectono-sedimentary environment, hence different lithofacies suites, which might have been deposited in different lows, giving rise to varied potentiality.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil