VGP Technical Report 17 - A petrophysical model of the Waarre Formation in the Port Campbell Embayment Onshore Otway Basin, Victoria.
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Product description:About the Victorian Gas Program: The Victorian Gas Program (VGP) is a comprehensive science-led program, incorporating geoscientific and environmental research to assess the risks, benefits and impacts of potential onshore conventional gas exploration and production. The program is also investigating the potential for further discoveries of onshore conventional and offshore gas in the Otway and Gippsland geological basins and assessing the feasibility of additional onshore underground gas storage in depleted reservoirs around the Port Campbell area. The VGP includes an extensive, proactive and phased community and stakeholder engagement program, through which the results of the scientific studies are being communicated. Executive summary: The opportunity for further underground gas storage (UGS) in depleted gas fields in the onshore Otway Basin is being investigated as part of the Victorian Gas Program (VGP). There are currently three depleted gas fields used for UGS in Victoria. These sites are in the Port Campbell area in the onshore Otway Basin. The Geological Survey of Victoria (GSV) engaged SEAL Energy Pty Ltd (SEAL Energy) to carry out a suite of technical studies to investigate the potential for further underground gas storage at existing depleted gas fields and known unproduced fields in the onshore Otway Basin. Six sites have been selected through a ranking process (Bagheri, 2019) for static and dynamic modelling. To support the modelling a revised petrophysical analysis of 18 wells from the Port Campbell Embayment has been performed. The purpose of this petrophysical analysis was to determine consistent petrophysical properties such as porosity, permeability and hydrocarbon saturations for input into further detailed technical studies as part of the UGS project. A small-scale field study was undertaken for wells from depleted or unproduced gas fields and five offset wells. The study methodology combined the available well log data with cuttings and core descriptions, core analysis data, pressure data and well-to-well correlations, to derive a petrophysical model for the principal reservoir (the Waarre Formation) across the area. A deterministic processing approach was applied including verification of results, so that each output generated at the various stages of the study was checked by ensuring similar results were achieved from multiple sources. Three sets of plots were output from the analysis. One set is referenced to measured depth (MD). The second set is referenced to True Vertical Depth sub-sea (TVDss). The third set illustrates uncertainties associated with the analysis, with actual distributions of each output curve. Each plot includes petrophysical corrections that were performed as part of this analysis and highlights interpreted gas-bearing zones in each well analysed based on two sets of water saturation cut-offs (50% and 70%). The resulting petrophysical properties were classified according to electro-facies as well as by stratigraphic zones. The final reservoir summaries with uncertainties will inform consistent inputs for the redetermination of Originial Gas in Place (OGIP) which, along with the electro-facies, will form an important input into the UGS detailed technical studies static and dynamic models. Bibliographic reference: SEAL ENERGY., 2020. A petrophysical model of the Waarre Formation in the Port Campbell Embayment, Onshore Otway Basin, Victoria. VGP Technical Report 17. Geological Survey of Victoria, Department of Jobs Precincts and Regions, Melbourne, Victoria. Download: The downloadable version of this report is supplied in PDF format (9.0 MB), accessible version (DOCX 8.0 MB) and Attachments A1-A4 (ZIP 36 MB). | ||||||
