Thermal Characterization of Eastern Offshore Sarawak Basin: Variation of Heat Flow and Implication to Hydrocarbon Prospectivity

Abstract

The problem of getting the variation of thermal maturity in-depth domain is insufficient with the maturity responses from vitrinite reflectance. The depth and areal distributions of thermal data can provide the map for relating thermal maturity and onset of overpressure and hydrocarbon generation. The thermal conductivity estimation of the right columns has been analysed by using logs and core measured data. In the determination of the geothermal gradient, the corrected logs Bottom Hole Temperatures are validated by the production test measured temperatures, which are close to the correct formation temperature. The product of the average thermal conductivity and the average geothermal gradient represent the terrestrial heat flow value at each well location. At the focused part of the study area, which is West Baram Delta, the trend portrays normal heat flow (55 mW/m2 - 65 mW/m2) with the geothermal gradient of 2 to 3°C/100m. Comparison of Time-Temperature Index (TTI) to the vitrinite reflectance of sediments in some wells demonstrates the basin has fluctuating heat flow in their development history. The heat flow-depth trends over the West Baram Delta is also related to overpressure occurrences. Hence, the geothermical parameters of the province can help in a better understanding of thermal maturity and pressure regime in the West Baram Delta.