Volcanics: A Commonly Underestimated part of Petroleum Exploration

Abstract

Conventionally, there has been an entrenched aversion to explore oil and gas in regions with volcanic geology. In other words, petroleum systems affected by igneous geology have not been considered with substantial oil and gas discoveries. However, the presence of volcanics is well known in many petroleum basins although not published in great details (including the North West Shelf of Australia), and there has been an increase in the number of hydrocarbon discoveries in volcanic basins worldwide. On the other hand, there has been volcanics geology factor associated with unsuccessful exploration wells. In the NWS of Australia, explorers care about the evidences as several unsuccessful wells, widely distributed in the area, have penetrated volcanics within the Triassic-Jurassic succession, which indicates a significant exploration risk. A primary purpose in writing this article was to illustrate that the presence of volcanics and their impacts on sedimentary rocks may lead to complex overprints for oil and gas exploration. Several 2D and 3D seismic datasets in addition to well information, from Barcoo Sub-basin of the NWS of Australia, were analysed and interpreted to demonstrate the fact that features we sometimes get with volcanics can be very misleading for hydrocarbon exploration. Volcanic rocks within the Triassic-Jurassic succession at the NWS of Australia are not considered favourable conditions for hydrocarbon accumulation. It is therefore important to develop an approach to better understand their impact on petroleum system and derisk prospects for exploration.