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Sedimentology And Reservoir Quality Of The Reids Dome Beds And Cattle Creek Group, Southern Denison Trough, Bowen Basin.

Wilson, Paul

Honours Degree, 2000

University of Adelaide

Abstract

Hydrocarbon recovery from the Reids Dome Beds and Cattle Creek Group, southern Denison Trough, is primarily restricted to the Merivale Field. Production tests of Permian sandstones in this region indicate significant hydrocarbon potential, but large lateral variation in reservoir quality is apparent. The primary aim of this thesis is to develop a detailed diagenetic history, describing all depositional and post-depositional events that have affected reservoir quality of the Reids Dome Beds and Cattle Creek Group, southern Denison Trough.

Sedimentation in the Denison Trough began during the Early Permian, depositing quartzose and lithic-rich sediments in a back-arc extensional basin. A full petroleum system, including source, exists within the Reids Dome Beds and Cattle Creek Group, making favourable further exploration and development.

Core logging formed the basis of the sedimentology section for this thesis, aiding in the development of a depositional model for Late Permian sedimentation in the southern Denison Trough. Twenty representative sandstone samples were taken and analysed using x-ray diffraction, thin-section petrography, scanning electron microscope and cathodoluminescence techniques.

Nine distinct lithofacies associations were identified in the Reids Dome Beds and Cattle Creek Group. These include Channel Sandstones (CS), Channel-fill Conglomerates (CC), Small Splay Channels (SSC), Proximal Crevasse Splay (CSP), Distal Crevasse Splay (CSD), Floodplain/Shallow Lacustrine (FP), Peat Mire/Swamp (PM), Lower Shoreface (SH) and Alluvial Fan (AF).

Diagenetic modifications influence reservoir quality of the Reids Dome Beds and Cattle Creek Group. These modifications involve a complex arrangement of compaction, alteration and dissolution, with abundant authigenic cements. Two broad stages of diagenesis are evident. The first of these events is co-incident with burial of the Bowen Basin sequence, while the second phase is related to deposition of the Surat Basin and injection of magmatic CO2 rich gas and/or water into the system.

The relative abundance of rock fragments and the amount of K-feldspar dissolution primarily control reservoir quality. K-feldspar dissolution accounts for the majority of porosity developed in sandstones of the units studied. Most intergranular porosity has been destroyed via the ductile deformation of rock fragments. Reservoir quality of studied sandstones is generally poor, but best in the Channel Sandstone (CS) lithofacies association.


Australian School of Petroleum
THE UNIVERSITY OF ADELAIDE

SA 5005 AUSTRALIA

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