New Unexplored Thailand Basin Frontier: North Malay Basin Post Rift Oligocene Deltas

Tatiya Uttarathiyang¹ and John D. Pigott^2
1PTT Exploration and Production Company Limited, Bangkok, Thailand
²Conoco Phillips School of Geology and Geophysics, University Of Oklahoma, Norman, OK

A 3D reflection seismic stratigraphic analysis of early post rift Oligocene sediments of the North Malay Basin, Gulf of Thailand, reveals an unexplored delta fairway which may have significant hydrocarbon potential. Three third order sequences were designated. Sequence TB1.1 (approximately 28.5 Ma to 30 Ma) represents a trangression and regression cycle which overlies the major Oligocene global eustatic sea level fall unconformity. Following a regional trangression, similarly offlapping Sequence TB1.2 is approximately 27 Ma to 28.5 Ma, whereas the uppermost Sequence TB1.3 is about 26 Ma to 27 Ma and is regionally sealed by a major trangressive shale.

Paleo-structure maps generated by flattening on the uppermost shale delineates the paleobathymetry of the depositional environments. Following an extensive seismic facies analysis constrained by limited borehole control, four general sub-environments were identified: an exposed ravinement surface, platform, ramp, and basin floor. In general, each sequence represents a general retreating clastic pulse as the basin deepens to the south. Without sufficient paleontologic constraint for differentiation, these deltaic sands may either represent marine deltas or low-lying lacustrine deltas. Nonetheless, these lowstand backstepping clastic wedges interupted by at least three stages of faulting may hold significant hydrocarbons for future Malay Basin exploration.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery