well logs
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Vertical stress is one of the three principal stresses and is an important parameter in geomechanical studies that are focussed on the prediction of pore pressure, fracture gradients, and wellbore stability. Variations of the vertical stress magnitude can be attributed to variations in lithology or diagenetic history, localised uplift, and overpressures caused by disequilibrium compaction. This study uses wellbore data from 102 open-file petroleum wells to characterise vertical stress within the onshore Canning Basin of north-western Australia. Vertical stress magnitudes are interpreted from density logs and checkshot data and at 1 km depth below the ground surface range from 20.5 MPa km-1 to 25.0 MPa km-1 with a mean value of 22.1 MPa km-1 (s.d. = 1.0 MPa km-1). Significant variation is evident within the calculated stress magnitudes, and when presented spatially, three regions of elevated vertical stress are identified: the Barbwire Terrace, the Devonian Reef Complexes of the northern Lennard Shelf, and the Mowla Terrace. Lithology, abnormal pore pressures, and tectonic uplift are investigated as potential mechanisms of the observed variation. Although abnormal pore pressures are identified, no direct correlation between overpressured areas and elevated vertical stress magnitudes is observed. The Canning Basin has an extensive history of uplift; however, there is little evidence for significant recent inversion. While uplift is likely to exert some influence over vertical stress magnitudes in the Canning Basin, the primary cause is interpreted to be lithological; areas of elevated vertical stress magnitude are also areas where thick intervals of carbonate sediments are present. Appeared in The APPEA Journal 59, pages 364-382, 17 June 2019
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<div>This data package provides petrophysical interpretations by Geoscience Australian and the South Australia Department for Energy and Mining (SADEM) for 23 wells generated in support of the energy resource assessments under the Australia’s Future Energy Resources (AFER) project in the Pedirka and western Eromanga basins. Interpreted petrophysical data in this data package include [BB1] [MB2] volume of clay/shale, porosity (total and effective), relative permeability, formation water salinity (NaCl equivalent), and apparent resistivity of water.</div><div> </div><div>The AFER project is part of Geoscience Australia’s Exploring for the Future (EFTF) Program—an eight year, $225 million Australian Government funded geoscience data and precompetitive information acquisition program to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, Geoscience Australia is building a national picture of Australia’s geology and resource potential. This will help support a strong economy, resilient society and sustainable environment for the benefit of all Australians. The EFTF program is supporting Australia’s transition to a low emissions economy, industry and agriculture sectors, as well as economic opportunities and social benefits for Australia’s regional and remote communities. Further details are available at http://www.ga.gov.au/eftf.This new data package consists of composite logs and supporting data which includes interpreted volume of clay/ shale, porosity, permeability and salinity.</div><div> </div><div>The data package includes the following datasets: </div><div>1) Composite logs (PDF)</div><div>2) Well logs (ASCII LAS)</div><div>3) Well header information (Microsoft Excel™)[BB3] [MB4] </div><div> </div><div>These petrophysical interpretations are being used to support the AFER Project’s play-based energy resource assessments in the Pedirka and western Eromanga basins by building 3D geological models that include derived rock property maps.