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.

Volcanic reservoirs: historic and current context

“…Exploratory success, is therefore, strongly related to the geological conditions of the environment in which the rock was cooled. The permo-porous properties of these igneous rocks have been underestimated in exploration for decades, as explained by Zahedi & MacDonald (2018). Understanding the petroleum system requires, a better comprehension of these rocks since they are often found nearby and even as prospects in volcanic basins.…”

“…In Australia, igneous rocks have been reconsidered in prospects where they were previously ignored (Holford et al, 2017;Zahedi & MacDonald, 2018;Bischoff, 2019). In New Zealand, pores and fractures have been identified in studies of physical volcanology in cores (Kennedy et al, 2017), reanalysis of ancient magmatic systems with reflection seismic (Bishoff, 2019), application of neural networks in 3D seismic data (Kumar et al, 2019) and study of seismic expressions of igneous rocks (Infante-Paez & Marfurt, 2018).…”

Impact of magmatic intrusion on diagenesis of shallow marine sandstones: An example from Qasim Formation, Northwest Saudi Arabia

“…Additionally, as the energy demand in the world is increasing, and hydrocarbon exploration moves towards deeper, morechallenging systems such as basins affected by igneous intrusion activity (Haile et al, 2019;Duffy et al, 2021;Rong et al, 2021), it is important to understand the interaction of diagenesis and magmatic intrusions on the reservoir quality of sandstones. This is primarily because magmatic intrusions can significantly impact diagenesis, thermal history, hydrocarbon source rock maturation, reservoir compartmentalization, and fluid migration pathways (Holford et al, 2012;Holford et al, 2013;Eide et al, 2017;Senger et al, 2017;Zahedi and MacDonald, 2018;Rong et al, 2021). Although sedimentary basins affected by magmatic intrusions are very common (e.g., the Shetland Faroe Basin, North Atlantic margin) (Muirhead et al, 2017;Schofield et al, 2017), Songlio Basin, China (Rong et al, 2021), Nequen Basin, Argentina (Monreal et al, 2009), Carnarvon Basin, Australia (Holford et al, 2013), there is a growing need to understand the influence of intrusion-induced diagenesis in order to reduce the risk of exploration.…”