New petroleum prospects in the northern Perth Basin

06 August 2012

A comprehensive geological assessment of a highly prospective basin offshore from Western Australia will help to reduce exploration risk for petroleum companies in a region where commercial successes have remained elusive.

The details of a series of new geological interpretations of the offshore northern Perth Basin, which has high potential for new oil and gas discoveries, has been revealed at the International Geological Congress in Brisbane today.

Geoscience Australia senior geologist, Dr Andrew Jones, said the basin analysis undertaken as part of the Australian Government's Offshore Energy Security Program (2007-11) provides new insights into the petroleum prospectivity of the basin.

“Analyses of key offshore wells, including relative age-dating of the sedimentary strata, have given new insights into source rocks that may have generated oil and gas in this area. These source rocks are more regionally extensive offshore than previously thought, where they have good to excellent potential for generating oil,” Dr Jones said

Dr Jones explained that this finding is supported by evidence of preserved oil within grains of quartz that have been found in a large number of wells in the basin. This indicates oil was formerly trapped in many parts of the basin, however most of these accumulations were likely lost from these systems when the Australian and Indian tectonic plates separated approximately 140 million years ago.

Modelling of fault systems by Geoscience Australia geologists suggests that it may be possible to predict where the oil or gas has been lost, and where it may still be preserved today.

As part of the basin analysis, Geoscience Australia also completed a marine survey in late 2011, searching for evidence of natural hydrocarbon seepage in the area west of Geraldton, Western Australia.

"Datasets acquired during the marine survey show evidence that is consistent with natural oil seepage strongly supporting the view that active petroleum systems on this part of the continental margin are widely distributed," Dr Jones said.

Dr Andrew Jones and his colleagues will be presenting details of their work at the 34th International Geological Congress in Brisbane on 6 and 7 August 2012.

For more information or to arrange interviews, please contact: Geoscience Australia 24 hour Media Hotline 1800 882 035

Topic contact: Last updated: August 9, 2012