Characteristics of Cenozoic source rock in south-western continental shelf of Vietnam

Abstract

At present, many production sharing contracts with oil and gas contractors have been signed by Petrovietnam for Blocks 46/07, 48/95, 50, 51, B and 52/97 in the south - western continental shelf of Vietnam. Series of exploration and production wells have been drilled by the contractors in most of these blocks where they discovered many oil and gas accumulations of different sizes in the studied area.

The authors used the geochemical data from thousands of rock samples gathered from the wells in Blocks 46/07, 48/95, 50, 51, B and 52/97 to define source rocks in the studied area. The results are as follows: the Oligocene and Lower Miocene sediments are categorised as source rocks in terms of organic matter potential; the Lower Miocene source rock containing kerogen type III and minor amounts of kerogen type I can be regarded as gas-prone; the Oligocene source rock containing kerogen type I (lacustrine algal) and mixture of type I and III can generate both oil and gas; oil potential of source rocks in the south eastern part of the studied area is higher than that in the north western part; and only source rocks of Oligocene and the lower part of Lower Miocene could supply hydrocarbon to the traps in the studied area.