Depositional And Diagenetic Controls On Reservoir Quality In The Early Permian Moogooloo Sandstone, Southern Carnarvon Basin.
Honours Degree, 1997
University of Adelaide
The Geological Survey of Western Australia has recently completed a major review of the petroleum geology of the Merlinleigh Sub-basin, within which the Moogooloo Sandstone has been recognised as a reservoir rock but predictions of poor reservoir quality have deterred exploration.
This study involved the logging of available core from the nine stratigraphic and petroleum exploration wells in the basin, the correlation of petrophysical logs between wells, an assessment of reservoir quality and diagenetic history from available petrographic reports and mapping of the interpreted deposition facies and reservoir quality.
The siliciclastics of the Moogooloo Sandstone were deposited in a range of environments from braidplain in the south to delta plain in the north. Three units within the Moogooloo Sandstone were identified. This study identified the basal unit as a pro-delta deposit and reinterpreted it as part of the Cordalia Formation.
Samples from the top half of the Moogooloo Sandstone were clean channel deposits. Samples have predominantly well-interconnected, open primary pores, with quartz overgrowth and grain contact dissolution being the major porosity reduction in the clean sands. Samples within the bottom half of the Moogooloo Sandstone were deposited in a river-dominated delta front. Samples have poorly interconnected micropores with clays filling pore spaces. Grain contact dissolution associated with the alteration of biotite to illite is a factor in porosity reduction.