Source Rocks and Oil Characteristic in the Phu Khanh Basin, Vietnam

Abstract

The Phu Khanh basin is situated within offshore, in the Middle of Vietnam which is next to the South China Sea seafloor spreading zone. This basin is influenced by both extrusion tectonics from strike‐slip of Red River Shear Zone and the extension tectonics from the South China Sea tectonic domain. The Phu Khanh basin is a frontier basin with eight wells drilled within the western flank of basin where the water depth less than 200m. There is no well drilled in Oligocene sequence which is believed the main source rock of the Phu Khanh basin and adjacent areas. Nevertheless, several oil samples are obtained means that petroleum system in this basin is proved. Results of oil samples geochemical analysis, especially in gas chromatography–mass spectrometry (GCMS) results indicate waxy oil generated from non‐marine source rock. More specifically, source rock could be deposited in the fresh lacustrine with mainly terrestrial input that is proved by oleanane indicator in geochemical data. Lower Miocene source rocks are found in numerous wells that show moderate quality with average of 1‐2% TOC values. Kerogen type is defined type I and type III means that source rock could deposit in lacustrine and high plant input environment, evenly, some coal samples are obtained in wells. Due to lack of real source rock in depocenter, information of oil samples is very important to define source rock characteristic of source rock. Then basin model also visualize how migration from depocenter to trap. Result of model demonstrates oil found in the well is from main depocenter of Phu Khanh. Evenly, oil is generated from moderated maturity level of source and very close to high plant supply area which quite consistent with GCMS data. Moreover, oil characteristic of oil samples in Phu Khanh is quite similar with oil found in adjacent areas such as Nam Con Son basin as well as Song Hong basin. By combination geochemical data, basin model, petroleum system, specially organism facies of source rock in Phu Khanh have been clarify and it should useful in further exploration.

AAPG Datapages/Search and Discovery Article #90349 © 2019 AAPG Hedberg Conference, The Evolution of Petroleum Systems Analysis: Changing of the Guard from Late Mature Experts to Peak Generating Staff, Houston, Texas, March 4-6, 2019