Gas hydrate in the North Carnarvon Basin, offshore Western Australia

Abstract

Analysis of hydrate systems across basins is not common, as most studies are focused on smaller sites. Using petroleum industry well and seismic data, we identify natural gas hydrate accumulations across the entire North Carnarvon Basin, offshore Western Australia. Out of 120 wells, 52 wells have evidence for gas hydrate, though hydrate is distributed throughout the hydrate stability zone in low concentrations. In addition, we do not observe a connection between the presence of hydrate in wells and deeper thermogenic gas reservoirs. From 3D seismic data, we observe bottom simulating reflections (BSRs) are very rare. In addition, while faults are common across the basin, shallow bright spots, which indicate shallow free gas, are uncommon. Based on all these observations from well and seismic data, we argue that hydrate across the North Carnarvon Basin formed predominantly from in-situ gas that is microbial in nature.