VGP Technical Report 43 - Dynamic modelling of the Fenton Creek gas field, 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 primary purpose of underground gas storage is to meet variations in supply and consumer demand. Gas is injected for storage during periods of low demand, then withdrawn during periods of peak demand. Storage capacity, injectivity and deliverability (withdrawal) are important characteristics of an underground gas storage site. Capacity is the volume of natural gas that can be stored in an underground storage facility. Injectivity is the amount of natural gas that can be injected, while deliverability is the amount of gas that can be withdrawn. The rates of injection and withdrawal change depending on the level of natural gas within the facility. 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 depleted gas fields in the onshore Otway Basin. Six sites (depleted gas fields) were selected through a ranking process (Bagheri, 2019) for static and dynamic modelling. The sites identified were Croft, Fenton Creek, McIntee, Mylor, Penryn and Tregony. Dynamic modelling is used to predict storage capacity, injectivity and deliverability. This is achieved by simulating the number of wells, tubing size and distribution rates of a potential UGS site to investigate the dynamic capacity of each site and to optimise potential development options. This report details the dynamic modelling of the Fenton Creek depleted gas field following the UGS dynamic modelling workflow (SEAL Energy, 2020a). Prior to dynamic modelling, publicly available data were compiled, analysed and reviewed. This included detailed reservoir engineering analysis on fluid properties, relative permeability, capillary pressure analysis and gas water contacts. This allowed for an analytical Original Gas in Place (OGIP) volume to be calculated using material balance methods, which assisted the history matching process. History matching involves adjusting the reservoir model until it closely reproduces historical production and pressure behaviour in the reservoir prior to dynamic modelling. A successful history match was achieved by adjusting key parameters such as horizontal permeability, water drive, relative permeability and fluid contacts. The history matched model allowed for scenario modelling to be simulated to investigate the dynamic capacity of the Fenton Creek depleted gas field. This work underpins the development options that are available to progress to commercial modelling. Nine scenarios were simulated by varying the number of wells, tubing size and distribution rates ensuring that the minimal wellhead pressure was used as a constraint when simulating withdrawal. The maximum bottom-hole pressure, limited to the initial reservoir pressure, was used as a constraint to simulate injection. Periodic injection/withdrawal cycles of nine and three months, respectively, were simulated for an operational period of 15 years. The dynamic modelling indicated the following:
Three scenarios representing low (35.4 Bcf), medium (41.4 Bcf) and high (48.6 Bcf) cases of total injected volumes over the life of the facility will be used in commercial modelling, undertaken in the next phase of the UGS project, to understand the commercial feasibility of developing the Fenton Creek depleted gas field as an underground gas storage site. Bibliographic reference: SEAL ENERGY, 2020. Dynamic modelling of the Fenton Creek gas field, Onshore Otway Basin, Victoria. Victorian Gas Program Technical Report 43. Geological Survey of Victoria. Download: The downloadable version of this report is supplied in PDF format (PDF 19 MB) & Att A1 (ZIP 9.7 GB). Note! Attachment is a large download and Petrel™ & Eclipse™ software is required to view or edit the files. Related products: | ||||||
