Cretaceous-Tertiary Sedimentary Filling Characteristics and Hydrocarbon Exploration Potential of Rakhine Basin in Myanmar

Hongping, Wang; Fuliang, Lu; Fan, Guozhang; Chaolin, Mao; Yiping, Wu; Sun, Hui

The Rakhine Basin is located in the eastern fringe of the Bay of Bengal and western coastal province of Myanmar. It is a frontier basin with limited number of exploratory wells in shallow water and virgin exploratory territory in deep water. The Shwe field in Block A1 was discovered in 2003, with proven gas reserves greater than 4.5 TCF. It was reported that the Shwe field is predominantly biogenic gas, mainly Methane with δ13C values to be from -60‰ to -70‰, and its reservoirs are the Late Pliocene submarine fan sandstones. Seismic sections crossing Block A1, AD1 and AD8 indicate the exploration potential in deep water is probably better. It is envisaged that significant future hydrocarbon accretions are likely to come from deepwater acreages.

The tectonic evolution of Rakhine Basin is closely related with the oblique subduction of the Indian plate beneath the Myanmar plate. This basin can be subdivided to three tectonic units, from east to west are thrust fold belt, gentle fold transitional zone and abyssal plain respectively. The basin contains thick Tertiary foredeep sediments lying on Upper Cretaceous abyssal sediments. In the upper Cretaceous there is a rift system which different from the passive rift system developed in the east coast of India. The rift system was possibly caused by mantle upwelling and thinning of crust when the Indian plate drifting over the Kerguelen hot spot to north in the Early/Middle Cretaceous. The Tertiary successions of the onshore portion in the basin contain deep marine, nearshore and deltaic sediments, but the offshore portion contain continental shelf, slope and basin floor sediments. The sedimentary sources are mainly from the Ganges and Brahmaputra rivers, and partly come from Myanmar onshore. When the top of the Miocene is flatten out of the seismic profile which crossing block A1, AD1 and AD8, they show clearly that Pliocene sediments in block AD1 and AD8 are significantly thicker than that in block A1, which indicates the deepwater areas may have greater exploration potential. The Middle Miocene to Pleistocene sequences indicates different characteristics of deepwater deposition based on RMS attribute analysis in block AD1 and AD8.

According to the petroleum systems and plays analysis in Rakhine Basin, the future exploration should aim at the Pliocene submarine fan sandstones, which located on the background of local low-amplitude anticline in gentle fold transitional zone.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013