Oil in Granites on Example of White Tiger Field, Vietnam

Tatyana Nickolaevna Nemchenko¹, Alla Semenovna Nemchenko-Rovenskaya², and Eugeniy Georgievich Areshev^3
1PetroAlliance, Moscow, Russia
²Vernadsky Institute of Geochemistry, Russian Academy of Sciences, Moscow, Russia
³State Commission on Reserves of the Russian Federation, Moscow, Russia

Oil genesis problem of unique pool in granites of White Tiger field has a great scientific and practical importance in the light of discovery and development of oil fields in basement rocks in various world basins, such as Shenli (China), Sarir (Libya), Bombay-Hay (India), La-Pas (Venezuela), Kern-River (USA). The most outstanding discovery is the unique White Tiger oil field on the shelf of Vietnam with reserves estimated at 700 million tons. White Tiger is a giant oilfield offshore South Vietnam (Kyulong depression producing from crystalline basement rocks and overlying Oligocene-Miocene clastic sediments. The main, massive-type, accumulation is contained in the basement granitoids. The aggregate explored geological reserves in the sedimentary cover ( Miocene and Oligocene horizons) are about half those in the basement. The problem of generation of oil accumulated in the basement rocks is a matter of discussion. Some researchers hold an opinion of abiogenic genesis that oil in the basement rocks has been formed owing to a flow of hydrocarbons from a deep (mantle?) source along fractures. An opposite opinion is biogenic genesis: the oil has been generated in sedimentary rocks and got into the fractured rocks of the basement due to lateral migration. Complex of geological, geochemical and analytical investigations of oils and rocks of White Tiger (carbon isotopic composition, gas chromatography, chromatography-mass spectrometry, biomarkers studies, “Rock-Eval”), allowed to make a conclusion, that oil of unique White Tiger field has biogenic genesis - main source rocks are oil-producing Oligocene rocks, characterized with high organic matter content.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece