Publication Name: The Sedimentary Basins of WA
Authors: G.R. Beardsmore & M.J. Altmann
Publication Volume: 3
Date Published: December 2002
Number of Pages: 36
Reference Type: Book Section
Abstract:
The Dampier Sub-basin hosts a number of significant hydrocarbon discoveries. The origin of these hydrocarbonsremains contentious due in part to poorly constrained maturity models. To address this problem, Santos Limited
undertook a study of the thermal history of the region. This paper presents the results of the first part of that study determining the present temperature and heat flow distribution. Thermal conductivity measurements were made on 165 core and outcrop samples covering all the major formations in the Dampier Sub-basin, and a
comprehensive review of all borehole temperature data was undertaken. The heat generated within the sedimentary column was estimated from natural gamma spectroscopy and total gamma count logs and included in the final heat flow model. We constructed a three-dimensional numerical model of the geological structure of the sub-basin, and solved it for temperature distribution, constrained by individual well-bore heat flow estimates. Results indicate a range of surface heat flow from about 55 to 65 m Wm-2, with higher values corresponding to elevated basement. It was not possible to model the observed elevated heat flow in the northeast of the study area using regional parameters. This implies either an anomalous heat source or anomalously low thermal conductivity beneath the Talisman Oil Field. The surface heat flow map provides a boundary condition for models of rifting heat flow decay and thermal maturation in the Dampier Sub-basin. The three-dimensional analysis allows estimates of heat flow in petroleum kitchens away from regions of well control.