High-Resolution Sequence Stratigraphy and Paleogeographic Evolution of the Middle Miocene Gas-Bearing Successions in Northern Malay Basin, Offshore Peninsular Malaysia

Mohamed Som, Mohd Rapi¹, Abdul Hadi Abd Rahman², Moh’D. Nurein Bushara³ (1) PETRONAS Research Malaysia, Bangi, Selangor, Malaysia (2) Universiti Sains Malaysia, Penang, Malaysia (3) PETRONAS Carigali Sdn Bhd, Kuala Lumpur, Malaysia

High resolution sequence stratigraphic analysis and interpretation, based on the facies description, log analysis and paleoenvironmental interpretation, identified major sequence boundaries and sequences within the E and D Groups (Middle Miocene) of the northwest of Malay Basin, offshore Peninsular Malaysia. Five sequence boundaries (E-10SB, E-8.2SB, E-7.1SB, E-6.6SB, and E-6.5SB) and five sequences are recognized within the E Group, and another five sequence boundaries (D-60.2SB, D-36.3SB, D-36.2SB, D-34.2SB and D34.1SB) and five sequences within the D Group.

The succession of sequences of the E-D-B Groups is the product of multiple cycles of relative sea-level fall and rise onto an incised valley. The E Group forms the Early Transgressive Interval, and comprises at least five high-frequency sequences (4th order?) of LST-TST-dominated, fluvial sequences. The Late Transgressive D Group was deposited as the result of relative sea-level rise. The inundation of the incised valley resulted in the devel­opment of an estuary at the beginning of Sequence D1, reaching its maximum size during the deposition of Sequence D5. The Regressive Interval (the HST) of the incised valley is partly or completely absent. It may have been eroded during the rapid regression marked by the fluvial-dominated, delta-forming system of the B Group. These paleogeographic facies models and sequence stratigraphic interpretation may be utilized as working models for future well planning.