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Reservoir Quality Of The Tangalooma Sandstone, Walloon Coal Measures – Surat Basin, Queensland: A Lithological And Compositional Investigation

Rohead-O’Brien, Hayley

Geoscience Honours Degree, 2011

University of Adelaide

Abstract

The Tangalooma Sandstone is the middle stratigraphic unit of the Walloon Coal Measures. The Walloon Coal Measures are the main resource unit within the Surat Basin which expands from central Queensland to central New South Wales. This thesis examines the reservoir quality of the Tangalooma Sandstone, of which very little information is available.

Determining the reservoir quality of the Tangalooma Sandstone within the Surat Basin is important not just to the coal seam gas industry, but also to the local communities that rely on fresh groundwater for drinking. It is currently not known if the Tangalooma Sandstone is a reservoir rock capable of carrying fluid or gas. This study will help to determine the reservoir potential of the Tangalooma sandstone through lithological and petrographical examination of the porosity, composition and texture of various samples throughout the Tangalooma Sandstone.

Two sections of core taken from the Tangalooma Sandstone unit were examined and described. A total of 10 samples were taken from each core for petrographic analysis. In both the core and petrographic analysis, a significant amount of clay cements was observed in most samples. Those lacking a clay cement, have a carbonate cement. Very little porosity is observed in the samples, occupying mostly clay cements. All samples are considered compositionally immature, with a somewhat co-dominance of quartz and plagioclase. The majority of the samples are matrix supported.

The above observations, indicate that flow throughout the sandstone may be hindered and slow. This means that there is a low permeability which indicates a low potential for reservoir quality.  However the use of other methods such as, mercury injection capillary pressure (MICP) and pore casing, may aid in determining reservoir quality may provide more accurate results.

 

Australian School of Petroleum
THE UNIVERSITY OF ADELAIDE

SA 5005 AUSTRALIA

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