Abstract: Thermal Regimes of Malaysian Sedimentary Basins

Mohd Firdaus Abdul Halim

Properly corrected and calibrated thermal data are important in estimating source-rock maturation, diagenetics, evolution of reservoirs, pressure regimes, and hydrodynamics. Geothermal gradient, thermal conductivity, and heat flow have been determined for the sedimentary succession penetrated by exploratory wells in Malaysia. Geothermal gradient and heat-flow maps show that the highest average values are in the Malay Basin. The values in the Sarawak basin are intermediate between those of the Malay Basin and the Sabah Basin, which contains the lowest average values.

Temperature data were analyzed from more than 400 wells. An important parameter that was studied in detail is the circulation time. The correct circulation time is essential in determining the correct geothermal gradient of a well. It was found that the most suitable circulation time for the Sabah Basin is 20 hr, 30 hr for the Sarawak basin and 40 hr for the Malay Basin. Values of thermal conductivity, determined from measurements and calibrated calculations, were grouped according to depositional units and cycles in each basin.

Within the Malay Basin, heat flow values are lowest in the north-central part of the basin. There the trend parallels basinal elongation, whereas to the south cross trends are prominent. In Sarawak, southwest Luconia and parts of Balingian have values comparable to those of the Malay Basin. Baram delta province shows the lowest values in Sarawak and an overall north-northwest trend bounded by the West Baram line. However, a narrow east-west trend extends into the modern delta. Sabah shows general trend, both cross trends, which are more prominent, and local trends parallel to basinal elongation are present.

AAPG Search and Discovery Article #90982©1994 AAPG International Conference and Exhibition, Kuala Lumpur, Malaysia, August 21-24, 1994