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Rakhine Basin in Myanmar — A Future Exploration Target

Hongping, Wang *1; Fuliang, Lv 1; Fan, Guozhang 1; Mao, Chaolin 1; Hui, Sun 1
(1) Petrochina Hangzhou Research Institute of Geology, Hangzhou, China.

The Rakhine Basin is located in eastern fringe of the Bay of Bengal and western coastal province of Myanmar. The tectonic evolution of Rakhine Basin is closely related with the oblique convergence of the Indian beneath the Myanmar plates. Three structural provinces are evident in the basin. From east to west they are: thrust and nappe fold belt, gentle fold transitional zone and abyssal plain. The Middle Miocene to Pleistocene sequences shows different characteristics of deepwater deposition based on RMS attribute analysis, which the Late Pliocene sequence dominantly exhibits meandering channel features, with its termination into fan lobes.

The occurrence of hydrocarbon seeps, small and shallow oil accumulations and recent large gas discoveries indicate the existence of an effective petroleum system in basin. The gentle fold transitional zone is the most favorable exploration area in Rakhine Basin. It’s located in the depocenter of basin during Oligocene to Miocene, and its shale comprises the principal source rocks in basin. With filling up and tectonic inversion in Late Miocene, low-amplitude anticlines occurred in this province, and it has undergone continuous tectonic activities during Late Miocene to Early Pliocene. Submarine fan sandstones in the Upper Pliocene series occurred on the background of its low-amplitude anticlines. The Shwe field in this province was discovered in 2003, with proven gas reserves greater than 4.5 TCF. The discovery is reported to contain predominantly biogenic gas, mainly Methane with δ13C values to be around -66‰, and its reservoir is the Late Pliocene submarine fan sandstones. The field has complex gas water distribution and independent pressure regime in each structure, and its gas distribution is charged by geological structure and lithologic distribution. The thrust and nappe fold belt has the features of intensive tectonic deformation, faults to the surface and poor hydrocarbon preservation conditions, and the abyssal plain is far away from hydrocarbon generation depression and lacks faults and structures. So their exploration potential is possible poor. But the abyssal plain exists possibly shallower biogenic system and deeper thermogenic petroleum system in the Cretaceous rift sequence.

Future exploration should typically direct at the traps formed by large submarine fan sandstone updip pinch-out or erosion channel lateral sealing on the background of local low-amplitude anticline in gentle fold transitional zone.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California