Insights into the Development of the Deepwater Phu Khanh Basin: Implications for Hydrocarbon Potential

Deepwater Phu Khanh Basin, offshore Vietnam covers an area of approximately 78,000 sq.km and is considered one of the last remaining frontier basins in SE Asia. To date, the deepwater Phu Khanh Basin has only been tested by two wells drilled in 2009 and 2011 on the western flank. Well 124-CMT-01X or White Shark is a non-commercial oil discovery and well 123-TH-1X has oil shows, thus proving the presence of a working petroleum system. Exploration of the Phu Khanh Basin initiated in 1972 in the inboard part of the basin, where relatively shallow water exists. However, exploration in the deepwater area only began in 2008 when PGS acquired over 14,500 line km of long offset, partly GeoStreamer™ multi-client 2D seismic, gravity and magnetic data. The basin lies on the central and southern Vietnamese continental margin, which marks the transition zone between the continental Indochina block and the South China Sea margin. The opening of the South China Sea during the Cenozoic, has strongly influenced the development of the basin. Interpretation of the seismic and gravity data support the existence of essentially two main depocenters (with up to 8 km of sediments) divided by an E-W trending Central Ridge/Shear Zone. Gravity and magnetic modeling also indicates that the basin sits on continental and transitional crust. Furthermore, extensive volcanics are interpreted to have been deposited in the basin, consistent with the active tectonism in the region. Regional extensional tectonics coupled with movement along the basin bounding shear zones has created a series of half grabens during the ?Palaeogene to Neogene times interspersed with two phases of inversion that are considered to have taken place during the Middle and Late Miocene times by analogy to the surrounding basins. This development has created a series of structural traps in the basin as supported by the seismic data. Extensive carbonate build-ups, at the basin edge and on structural highs, are clearly observed on the seismic data and have been interpretative to occur during the Early Miocene. In addition, potential turbidite fans have been mapped off the shelf in the northern part of the deepwater Phu Khanh Basin. This study indicates that the interplay between regional tectonics and depositional systems, coupled with the White Shark oil discovery and the seismically abundant gas chimneys, have given rise to a basin that can be considered to be a potential hydrocarbon province.

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