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Hydrocarbon Prospectivity of the Onshore Stansbury Basin, South Australia Samuel Paulo da Graça Correia, 2013

Honours Degree, Bachelor of Science (Petroleum Geoscience)

Australian School of Petroleum,

The University of Adelaide

Abstract

The Early to Middle Cambrian Stansbury Basin covers approximately 15,000 km2 of South Australia
and lies mainly beneath Gulf of St. Vincent and southern Yorke Peninsula. The aim of this project is
to assess the petroleum system elements of the Stansbury Basin in order to determine hydrocarbon
prospectivity in Petroleum Exploration Licence (PEL) 606 which covers most of Yorke Peninsula.
Data from previous analyses such as Routine Core Analysis (RCA), Total Organic Carbon (TOC) and
vitrinite reflectance were compiled together with twenty two independent samples taken during
core inspections at the Department for Manufacturing, Innovation, Trade, Resources and Energy
(DMITRE) core library. Data from RCA showed that core porosities in the area range from 1-20% and
permeabilities range from 0-452 mD. Data from geochemical and rock evaluation analyses showed
that TOC and vitrinite reflectance in the area are less than 0.5% and 2.5 respectively.

This study highlighted that the Minlaton Formation and the Yuruga Formation appear to have low
porosity (<5%) and permeability (<10 mD) and are potential seals for the Stansbury Basin reservoirs.
This study confirmed that the Kulpara Formation is the potential reservoir in the Stansbury Basin.
The formation outcrops in the Yorke Peninsula and is presumed to extend beneath the Gulf of St.
Vincent. It is believed to have good reservoir properties with porosities and permeabilities exceeding
5% and 10 mD respectively.

Potential source in the Stansbury Basin lies within the Early Cambrian Parara Limestone, that has
TOC values less than 0.3% and vitrinite reflectance in the range of 1.1 to 2.1. The formation is
organically lean, gas prone and presumably extends beneath Gulf of St. Vincent to the Early
Cambrian Heatherdale Shale on the Fleurieu Peninsula.

Geological map and seismic data interpretation indicated that Cambrian sediments deepen and
thicken towards the southern part of the Yorke Peninsula. Folding of Cambrian sequence suggests
the potential for structural traps being present in the Stansbury Basin. Potential traps observed in
the area are mainly fault-dependent.

Burial history modelling showed that Cambrian successions and normal faults developed during Early
Cambrian extension were later reactivated during the Delamerian Orogeny, Alice Springs Orogeny
and Tertiary Uplift during Miocene. Thermal maturity modelling was constructed using these three
deformation events and indicated that the Early Cambrian Ramsay and Parara Limestones are within
dry gas window and the Middle Cambrian Yuruga Formation is in the oil window.

This study represents a substantial review of the potential sources, reservoirs and seals in the
Stansbury Basin with additional studies on regional geology that can be used to determine areas that
prospective for hydrocarbons. Areas within PEL 606 that have potential for hydrocarbons are located
in the southern part of Yorke Peninsula and outside PEL 606 in areas beneath the Gulf of St. Vincent.


Australian School of Petroleum
THE UNIVERSITY OF ADELAIDE

SA 5005 AUSTRALIA

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