The Cretaceous-Cenozoic volcanic record of the Gippsland Basin: origin, nature and significance for the energy transition

Abstract

Mafic volcanic rocks, typically basalts of mainly late Cretaceous age, have been intersected by Gippsland Basin wells. Intersections of volcanic rocks primarily occur along the basin-bounding Rosedale Fault System in the northern part of the basin, where they exhibit a close spatial correspondence with high-CO2 content gas accumulations. Though petrographic data indicates that the basalts have been variably altered to clays and carbonates, they provide the top seals to numerous hydrocarbon accumulations, most notably at the Kipper Field. Despite the widespread distribution of these volcanics and their relevance to petroleum systems, they have received only sporadic attention over the past few decades. Here we combine petrophysical, geomechanical, geophysical and geochemical datasets to elucidate the origin of the volcanic record of the Gippsland Basin, and to evaluate their potential role in the decarbonisation of the basin, for example through providing opportunities for intra and sub-basaltic storage of CO2.