Lowering the cost of finding onshore and offshore oil and gas resources many kilometres below the surface is the focus of new research. TIM THWAITES reports

Article from resourceful: Issue 11

RESEARCH NEWS

Australia has vast amounts of gas and possibly also of oil in its onshore and offshore frontier basins.

Oil pipes

But, much like the case with Australia's mineral resources, most of the easy-to-find oil and gas resources have already been discovered, leaving only reserves that are typically deeper than four kilometres under the ground or ocean.

These reservoirs are mainly in poorly explored regions where little geophysical data has been acquired and/or they are so deep that they defy established methods used to identify hydrocarbons from their geophysical signatures.

Through its Deep Earth Imaging Future Science Platform, CSIRO is working on reducing the business costs of finding new reserves by rendering the blanketing layers of earth transparent and sharpening the image of what's underneath.

It will take clever science to do it, but according to the director of CSIRO's onshore gas research, Dr Damian Barrett, the multidisciplinary and multidimensional nature of the work suits an organisation like CSIRO rather than the traditional service suppliers of innovation to the energy industry.

Looking for oil and gas is a very different proposition to searching for water or minerals. For starters, we are talking about working at depths of kilometres, rather than hundreds of metres, usual for water.

"With oil and gas, 90 per cent of the data we use is seismic, especially offshore," CSIRO's research group leader for energy exploration geosciences, Dr Ben Clennell, says.

"We are only looking in sedimentary sequences, and the range of possible geometries we encounter is smaller — typically a flat layer, rather than a blob or some other weird shape."

The approach to sharpening up the image of the deep earth, Dr Clennell says, will be centred on a technique called Bayesian updating.

"You start with a model of what the geologists think might be there – which can be very fuzzy – and then you update it using real geophysical data."

The process is informed by a lot of geological understanding, which constrains and focuses the answers you get from analysing geophysical data.

"The end goal is to get fluids within the rock out to the world," Dr Barrett says.

"That depends on the nature of the pore structure and the stresses on the rock. The leap of science is to be able to relate the large-scale measurements of seismic signals to the small-scale characteristics of pore structure of the rock, which determine how fluids, such as oil and gas, flow. And it requires very sophisticated mathematical modelling."

The Deep Earth Imaging platform is only just at its beginning, but there are several areas where researchers are looking to develop and demonstrate their capabilities. The team will focus its offshore efforts on the Browse Basin off north-west Western Australia and the Great Australian Bight. Whereas, onshore, the focus will be on the Beetaloo Province in central Northern Territory, the Cooper Basin on the border of Queensland and South Australia, the Canning Basin in the Kimberly and the Perth Basin in Western Australia.

Dr Barrett says that currently the cost of drilling a well in Australia is more than two and a half times that in the United States. That's a barrier to the development of oil and gas.

"In general, Deep Earth Imaging is looking to provide a productivity jump – a quantum leap," he says.

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