- White Tiger oil field
The White Tiger oilfield (also Bach Ho) is a major oilfield in the Cuu Long basin of the
South China Sealocated offshore due east of the Mekong Deltaof Vietnam. The field contains major reserves hosted within highly fractured granitic basement rocks. The Cuu Long basin is a riftzone developed during the Oligoceneto Early Miocene. The rift occurred in Jurassicto Late Cretaceous graniteto granodioriteintrusions.Nguyen Du Hung and Hung Van Le, "Petroleum Geology of Cuu Long Basin - Offshore Vietnam", Search and Discovery Article #10062 (2004), http://www.searchanddiscovery.net/documents/2004/hung/index.htm ] [Tatyana Nickolaevna Nemchenko, "Oil in Granites on Example of White Tiger Field, Vietnam", AAPG & AAPG European Region Energy Conference and Exhibition (November 18-21, 2007) Technical Program (abstract) http://aapg.confex.com/aapg/2007int/techprogram/A113544.htm ] The fractured granitic rocks occur as a horstoverlain and surrounded by Upper Oligocene lacustrine shalesource rocks.
White Tiger is not the only oil field convincingly shown to be hosted in granite;http://www.geoscience.co.uk/geofrc/geobaseasia.html Basement reservoirs in Asia] however, inspection of the seismic profile of the area shows faulted basement passive margin which is sealed by an onlapping
sedimentarysequence. [Hydrocarbons in Crystalline Rocks, 242 pages, Geological Society of London; (January 2003) ISBN: 1862391378]
It is plausible that the oil has migrated laterally from the lowermost, mature sediments into the fault systems within the granite. The
seismicprofile shows a definite basement horst with onlapping sedimentary source rocks, draped by a reservoir seal. [http://www.aapg.org/explorer/2005/02feb/vietnamcuulong.cfm CuuLong] This trap view would see the oil migrate up the horst bounding faults from the lower source units, into the trap unit draped over the top.
The White Tiger field was developed by the joint Vietnamese Russian entity Vietsovpetro, in the 1980s and 1990s, using the methodology of abiogenic oil.Fact|date=June 2008 However, upon examination of the source rock and oil content, petrogeologists have emphasized that the oil's components indicate a
lacustrineorganic facieswith lipid-rich, land-plant debris and fresh-water algal material, refuting theories of abiogenic origin in this area.
Petroleum samples from the White Tiger oilfield contain biomarkers which "indicate a lacustrine organic facies with lipid-rich, land-plant debris and fresh-water algal material," which indicate that it is of biological origin. [http://www.aapg.org/explorer/2005/02feb/vietnam.cfm Vietnam 02:2005 EXPLORER ] ]
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