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Petroleum Prospectivity of the Permian, Triassic and Jurassic sediments adjacent to the Peedamullah Shelf, Carnarvon Basin, Western Australia.

Denver, Thomas E.

Honours Degree, 2005

University of Adelaide

Abstract

The Petroleum prospectivity of the Jurassic, Triassic and Permian sediments adjacent to the Peedamullah Shelf in the Carnarvon Basin, offshore Western Australia is being investigated by Strike Oil Limited.  The proximity of these sediments adjacent to the Peedamullah Shelf in the Carnarvon Basin, Western Australia, to existing fields and infrastructure and an existing petroleum market makes them a prime target for exploration.

The area of interest extends along the Flinders Fault from north of Barrow Island to south of Thevanard Island.  A detailed understanding of the geometry and depositional environment for shelf sand reservoirs is fundamentally important in reducing risk for under-explored shelfal petroleum systems.  The work undertaken was a regional scale study including correlations of higher order systems, with the aim of increasing understanding and decreasing the risk involved in finding reservoir sandstones adjacent to the Peedamullah Shelf.  Well control in the Permian, Triassic and Jurassic is limited, but the available wells have been studied using tools such as sequence stratigraphy, palynology and well log signature correlations.

The aim of this study is to identify potential reservoir seal pairs, make some informed predictions as to their distribution and quality and hence the petroleum prospectivity of the Permian, Triassic and Jurassic sediments adjacent to the Peedamullah Shelf in the Carnarvon basin.

Thirty-seven wells were studied on and adjacent to the Peedamullah Shelf, and 16 were chosen for sequence stratigraphic study using copies of the wireline well log information and well completion reports.  This information combined with a literature study was used to develop an understanding of the palaeogeography, sediment supply, depositional environments and approximate depositional time frame for the study area.  Based on this the concepts of sequence stratigraphy were used to divide the sediments of the study area into conformable stratigraphic sequences.  Net sand within each of these sequences was then calculated and displayed to produce sequence specific regional reservoir potential isopach maps.  From these findings further interpretation of depositional environments, styles and sediment supply were made, in particular with regard to reservoir facies deposition.

The interpretation of two separate sediment supply sources (to the NE and South of the study area) during the Permian and Triassic deposition, and the interpretation of two specific reservoir facies (sand) depositional areas within the study region, add to the potential petroleum prospectivity of the sediments adjacent to the Peedamullah Shelf.

Findings of the study may lead to the generation of depositional models and palaeogeographic models/maps which can be used to locate potential reservoir sands and likely locations for hydrocarbon accumulations.

Australian School of Petroleum
THE UNIVERSITY OF ADELAIDE

SA 5005 AUSTRALIA

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