Fluid inclusion analysis to unlock oil and gas potential

The challenge

Lowering the cost of oil and gas exploration

Oil and gas field operators are always seeking to extract more from existing permits or prospect in new areas.

But offshore prospecting costs are significant. To reduce the risk of drilling in areas that do not have sufficient resources for a successful well, exploration companies collect large amounts of technical information on many targets.

Fluid inclusions – tiny encapsulations of fluid that trap oil, gas and water in rock – are a useful source of information for exploration companies.

If enough of these inclusions are found near a potential drill site, they can be used to answer key questions for exploration such as whether oil and gas are likely to be found at a particular location, and the source and type of hydrocarbon present.

Our response

Analysing fluid inclusions

CSIRO has been analysing fluid inclusions in sedimentary rocks since 1989, and our pioneering work in this area is recognised worldwide.

We have developed a suite of techniques to analyse the history of palaeo-fluids in sedimentary basins:

• Grains containing Oil Inclusions (GOI™) identifies palaeo-oil zones in rocks from a current oil zone or from rocks that were in a oil zone and are now saturated by gas or water.
• Raman spectroscopy detects dissolved hydrocarbon gases (CH₄, C₂H₆, C₂H₈) and non-hydrocarbon gases (CO₂, H₂S, N₂, H₂) directly.
• Thermometric measurements of water inclusions can be used to evaluate how the composition and salinity of aquifer water has changed during different phases of a reservoir filling with hydrocarbons.
• Resistivity from Oil–water Inclusions (ROI™) determines the resistivity of water (a measure of the concentration of dissolved salts) in the reservoir at the time of oil accumulation; with Raman spectroscopy, ROI can also be applied to irreducible water salinity in gas reservoirs.

Fluid inclusions capture pristine samples of the fluid in the rock when they form. Even if the fluid in the surrounding rock has changed, fluid inclusions can be analysed to determine the fluid history of the rock and the prevailing thermal conditions.

This means that the technology provides information about the past movement of both oil and gas in the pore spaces of rocks to:

• detect palaeo-oil zones and potential for nearby prospects
• detect oil migration
• predict regional hydrocarbon charge and type
• determine when reservoirs were charged
• estimate oil and gas reserves
• identify sources for oil (when used with related CSIRO technologies).

This helps to lower the cost and avoid higher risk exploration.

Expertise

Our multidisciplinary team has expertise in:

• specialist fluid inclusion studies
• petroleum geosciences
• spectroscopy
• microthermometry
• petrography/diagenesis.

Facilities

We use a range of facilities to conduct research and provide analytical services, with:

• GOI™ microscopy workstations with UV fluorescence illumination and spectrometer
• Horiba LabRam HR Evolution Raman spectrometer
• Linkam Scientific thermometric heating/freezing equipment.

The results

Providing trusted advice based on quality science

Our work has contributed to the management of risk in drilling for new oil and gas reserves by:

• informing decisions to explore in certain offshore sedimentary basins
• selecting targets for exploration wells
• characterising the evolution of oil and gas sources, and the alteration events that affect their value.

As a trusted advisor, we deliver commercial and research services to the Australian and international petroleum industry. We collaborate with other Australian and international research organisations like Geoscience Australia, and with fluid inclusion laboratories such as:

• Centre de Recherches sur la Geologie des Matieres Premieres Minerales et Energetiques (CREGU), France
• United States Geological Survey, United States
• Virginia Polytechnic Institute and State University, United States
• Centro de Pesquisas Leopoldo Américo Miguez de Mello (CENPES), Brazil.

Past projects include:

• working with BP Developments Australia, through the Great Australian Bight Research Program, to de-risk some elements of petroleum prospectivity that are only accessible from fluid inclusions
• working with Geoscience Australia to better understand the prospectivity of the offshore northern Perth Basin
• investigating palaeo-temperature, salinity and gas content of water inclusions from the aquifer underlying large gas accumulations in the Browse Basin.