Authors / CoAuthors
Wang, L. | Consoli, C. | Causebrook, R.M.
Abstract
This study aimed to assess the CO2 geosequestration potential of the Upper Campanian Caswell Fan (Upper Cretaceous), Caswell Sub-basin, Browse Basin, through an integrated reservoir study. The study focused on the basin geology, sedimentology and incorporated reservoir evaluation from well logs, seismic interpretation, velocity modelling, and time-depth conversion. The final stages included 3D grid construction and reservoir modelling through geostatistical analysis for lithofacies and petrophysical properties, which collectively were utilised to construct the geological reservoir model using the GoCadTM Software. Finally, a CO2 storage capacity assessment was completed based on the model. Under the controls of regional structural geology, sedimentary supply, sea level eustacy and palaeoclimate, several turbidite fans were formed during the Campanian Stage (Late Cretaceous) on the northwest shelf of Australia (Benson et al., 2004; Blevin et al., 1997). The lowstand Caswell Fan is a basin floor fan and was deposited predominantly as a series of sheet-like sands (reservoir) and succeeded by a deep marine mudstone (seal) after fan abandonment. The Browse Basin has extensive seismic survey coverage and both regional 2D and the North Browse 3D seismic survey data were interpreted to construct the structural pattern for Caswell Fan. The stacking velocity of the Caswell Sub-basin was used to establish the average velocity, which was validated by check-shot velocity and well marker data from wells. The data was then time-depth converted. Utilising the well-log data of the four wells that have intersected the Caswell Fan, i.e. Caswell-1, Caswell-2, Marabou-1 and Walkley-1, the percentage of shale within the formation (V-shale) was calculated, which in concert with rock descriptions, was used to define three lithofacies, namely sandstone, siltstone and non-reservoir rocks. The effective porosity and permeability were calculated from the well logs. Within the grid system of the Caswell reservoir, sequential Gaussian simulation has been employed to populate the reservoir properties, such as V-shale, porosity and permeability. In order to integrate the distribution pattern from seismic amplitude, kriging with locally varying mean technique was used for interpolation during sequential Gaussian simulation process. Within the reservoir model, proximal to the wells, the average porosity of the cells is 0.1828, the average permeability is 88.5 millidarcy, and the sand percentage is nearly 80%. The maximum true thickness of the reservoir within the Caswell Fan in the area of interest is 260.53 m. The total pore volume in the area of interest within Caswell Fan is 1.69 ×1010 m3. The density of supercritical CO2 at the top of Caswell reservoir is 649.55 kg/m3, and the characterised storage potential of the Caswell reservoir is 296 million tonnes using a median storage coefficient for clastic formations of 2.70% (P50) (US DOE methodology). For the purpose of reservoir simulation, the constructed geological grid system was upgridded, which included the reservoir parameters. The coarse grid model will be used for dynamic simulation later.
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nonGeographicDataset
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73298
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- GA PublicationRecord
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2012-01-30T00:00:00
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