Heat flow and thermal maturity modelling in the Northern Carnarvon Basin, North West Shelf, Australia

Abstract

The Northern Carnarvon Basin is located at the southern end of the North West Shelf of Australia. It was developed by rifting during the Jurassic–earliest Cretaceous. Heat flow and thermal maturity in seven wells, from three sub-basins, Rankin Platform and Exmouth Plateau of the Northern Carnarvon Basin, were modelled using BasinMod 1D program. Multiple thermal maturity parameters were used to constrain the influence of anomalously low vitrinite reflectance. Those T max data with reliable quality can be applied to correlate with vitrinite reflectance, establish thermal maturity and calibrate the modelled results. The modelled results indicated that the measured maturity data in some wells were consistent with the rift heat flow model (Jarvis & McKenzie) associated with the Jurassic rift and the earliest Cretaceous seafloor spreading events. The maximum values of heat flow were in the range from 67 mW/m 2 (Jurabi-1) to 105 mW/m 2 (Bowers-1) in the Exmouth and Barrow Sub-basins. On the Exmouth Plateau, the maximum values of heat flow were modelled to be 72 mW/m 2 in the Jupiter-1 well and 78 mW/m 2 in the Investigator-1 well. These maximum values were modelled to occur during syn-rift phase, which were 29–88% and 33–37% greater than their current heat flow values in the sub-basins and on the Exmouth Plateau, respectively. This study suggests that maturity indicators are less diagnostic of rifting thermal histories if the maximum thermal effect is associated with Cretaceous and Cainozoic burial in this basin.