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Greater McArthur Basin unconventional hydrocarbon and metallogenic potential
The greater McArthur Basin is a regional correlation between the Palaeo to Mesoproterozoic McArthur and Birrindudu basins and the Tomkinson Province.
It has an approximate area of 550,000 km2 in the northern Northern Territory.
NTGS projects in the Greater McArthur Basin aim to:
- develop an understanding of the basins architecture and tectonic framework, and resolve the relative timing of tectonism across its major structural elements
- characterise and clarify its depositional history through typing of major stratigraphic units, and address existing issues of correlation across the basin
- Integrate the tectonic and stratigraphic history of the basin to provide the basis for identification of mineral deposit models related to specific stratigraphic units, identification of key fluid pathways and timing, and provide valuable datasets to assist with mineral and hydrocarbon exploration.
The unconventional hydrocarbon and metallogenic assessment project aims to target prospective horizons within the McArthur Basin succession and correlative units within the Birrindudu Basin and the Tomkinson Province.
For more information about the geology of the Greater McArthur Basin, Birrindudu Basin and Tomkinson Province go to geology of the Northern Territory on the Northern Territory Government website.
An assessment of the unconventional hydrocarbon prospectivity will be undertaken through systematic acquisition and analysis of key datasets required apply resource assessment methodology for determining the unconventional hydrocarbon potential of sedimentary basins.
Identification of prospective shale horizons entails the following parameters:
- marine shales with Type I/II kerogen (HIo: 250-800 mg HC/g rock)
- organic rich source rock with TOC >2% (non-residual organic carbon)
- maturity of dark organic-rich shale is between 1.1 – 3.5% Ro
- low oil saturations (<5% So)
- brittle mineral content (quartz, carbonates, feldspars) >40%, clay mineral content <30%
- low permeability (<1000-ηd), porosity (4-7%)
- effective thickness of organic–rich mudrock ≥ 30 m
- continuous mappable systems
- slightly to highly overpressured
- metallogenic sampling program for precious and base metals, including geochemical characterisation for evidence of metal mobilisation.
Highlights of the progressive acquisition of datasets for the project include:
- 4501 sample points across 115 wells
- sampling is mainly from the Roper Group, with limited sampling from the McArthur, Tawallah and Limbunya Groups
- selected cores have been sampled to 5m intervals, with previously unsampled cores being sampled between 10 – 5m intervals through shale intersections
- sample analysis includes new data for TOC, Rock-Eval pyrolysis, X-ray diffraction, CHONS-Fe Sorg elemental kerogen, porosity, permeability, fluid saturations, gas chromatography and biomarker studies, organic petrology, rock mechanics and kerogen kinetics studies
- significant increases to geological, geochemical and rock property knowledge of the greater McArthur basin stratigraphy
- metallogenic sampling program for precious and base metals.
The project has initially focussed on building the datasets for an assessment of the Beetaloo Sub-basin.
The 2015/16 sampling program concentrated on the Favenc and Glyde Packages of the McArthur Basin, which include the prospective black shales of the McArthur Group.
Revie D, 2015. Unlocking potential for unconventional petroleum resources in the frontier McArthur Basin, Northern Territory. In Annual Geoscience Exploration Seminar (AGES) 2015. Record of abstracts. Northern Territory Geological Survey, Record 2015-001.
Revie D, 2015. Methodology for shale analysis of onshore basins, Northern Territory: a compilation of analytical methodologies used by Weatherford Laboratories (Australia) Pty Ltd. Northern Territory Geological Survey, Record 2015-004.
Revie D and Normington VJ, 2018. Shale resource data from the greater McArthur Basin. Northern Territory Geological Survey, Digital Information Package DIP 014.
Revie D, 2016. From the back of the shed to the forefront of exploration: what the NTGS core store is revealing about the Roper Group shales of the greater McArthur Basin. In Annual Geoscience Exploration Seminar (AGES) Proceedings, Alice Springs, Northern Territory, 15–16 March 2016. Northern Territory Geological Survey, Darwin.