Distribution of Present Heat Flow in the Phu Khanh Basin, Offshore Vietnam

Abstract

This study aims to determine the distribution of present heat flow in the Phu Khanh basin from shallow water to deep water throughout the basin. The results from 42 present heat flow data points extracted from the global heat flow database by Goutorbe et al. (2011) indicated that there is an uneven distribution of the present heat flow in the research area. Heat flow accumulation in uplift structures in the north-west direction (78 - 86 mW/m2) of the Phu Khanh basin is usually higher than in trenches or deep depressions in the south-east direction of the basin (58 - 72 mW/m2). This is due to the sediment layer up to more than 10,000m thick in the deep water of the Phu Khanh basin. As a result, heat flow values in deep water are significantly lower than in shallow water of the Phu Khanh basin. The thick sediment layer acts as an insulator that prevents heat flow from escaping to the surface. The mean values of present heat flow calculated from wells TH - 1X and CMT - 1X are 85.60 mW/m2 and 83.20 mW/m2 respectively. These values are relatively consistent with the predicted results from Kriging 42 data points extracted from the global heat flow data set in the study of Goutorbe et al. (2011). The high present heat flow values can be explained by the fact that the Phu Khanh basin is still experiencing thermal subsidence because of its relatively young age (approximately 35 million years). This basin has not yet regained its thermal equilibrium value after the Early Oligocene - Miocene extension stage, so the present heat flow value is still high in this basin.