Simulating the Conductive and Hydrothermal Maturation of Coal and Coal Seam Gas in the Bowen Basin, Australia

Abstract

We model the hydrothermal maturation of hydrocarbons in the Bowen Basin of Australia with the program HYDROMAT (Lopez et al., these proceedings). HYDROMAT is used to determine the vitrinite reflectance and the generation of bulk hydrocarbons, hydrocarbons with one to four carbons, and hydrocarbons with five carbons or more during the evolution of the Bowen Basin. The uplift, subsidence, erosion, deposition, fluid flow and heat transfer, and thermal history of the Bowen Basin are reconstructed in order to model the maturation history of the hydrocarbon producing sediments. The effect of high temperature Cretaceous intrusions on the Bowen Basin is also modeled. We focus on the German Creek and Pleiades coal seams and find good agreement between our results and actual data for vitrinite reflectance. Our results support previous experimental studies, which suggested that hydrothermal fluid circulation and high temperature sills and dikes created the high ranking coals and methane gas deposits found in the Bowen Basin. According to our modeling results the regional Triassic high heat flow event was responsible for generating the largest fraction of the total hydrocarbons produced during the entire history of the Bowen Basin. This is consistent with the coexistence of bitumen and minerals of hydrothermal alteration in the Bowen Basin sediments.