Special System Approach to Assessing the Oil Potential in Fractured Basement in the White Tiger Field, Cuu Long Basin, Offshore Vietnam

Abstract

The basement has been considered to be rock that is not capable of archiving oil and gas, having very little primary porosity and/or permeability; however, under certain conditions, when the basement has been strongly weathered, secondary porosity and very good permeability can develop. An example is the typically granite basement rock in the White Tiger Field, which has an apparent porosity of up to 10% and a permeability of up to thousands of mD. This basement rock has become a high-quality petroleum-bearing rock. In the world, there are over 200 oil fields in fractured basement. Exploration and exploitation have proved that the oil in the fractured basement of the White Tiger Field is a special oil body, and constitutes the main oil reservoir rock in Vietnam, contributing 80% of the oil production in the early years of the 21 century. The precise mechanisms involved in forming the oil remain unresolved, however. Approaching the system from three perspectives–system reflection, research of sustainable relics and specific analysis – was found to be most appropriate in determining the mechanisms behind the formation of cavern and fracture systems in basement rock.