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Multiple Provenances on Predicting Reservoir Quality: “Source to Sink” Sedimentation in a Dryland Fluvial-Aeolian System, Western Lake Eyre Basin, Central Australia

Menacherry, Saju; Payenberg, Tobias; Lang, Simon; Heins, William

Reservoir quality of is primarily controlled by a range of parameters, including grain size, sorting, and modification of the original sediment composition through the diagenetic processes of compaction and cementation. The ability to quantifiably predict such diagenetic processes (controlled by lithology, pressure, temperature, pore fluids type, grain size, and amount of fluid flow) is a significant factor in predicting reservoir quality.

The initial sediment composition, texture and grain size are functions of hinterland processes: provenance, tectonic setting, climate, sand evolution and transportation, and the depositional environment. Sands from the modern dryland Umbum Creek, western Lake Eyre Basin, Central Australia reflect the nature of the hinterland region and drainage basin. Evolution of sand composition throughout the river course is mainly related to the changes in the relative proportion of contributing bedrock lithologies. Six petrographic provenances were identified and established in the Umbum Creek drainage basin. Upstream Palaeoproterozoic and Neoproterozoic provenances supply lithic grains and metamorphic minerals to the stream's sand, whereas quartz is mainly sourced from reworked older sedimentary units further downstream. The initial rock compositions (mineralogy, texture and grain size) are the main influence on diagenetic processes such as cementation, quartz overgrowth, mechanical and chemical compaction, grain breakage and pressure solution. In the case of the Umbum Creek sands, the medium to coarse grain size, 88-92% of quartz, less than 2% of feldspar and less than 10% of lithic fragments, together with subrounded to rounded grains, moderately well sorting and very little in clay content, leads to a suitable candidate for good reservoir quality, if buried. A similar analysis of the ‘source to sink' sedimentation system of a petroleum basin could lead to a better assessment of reservoir quality prior to drilling.

 

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013

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