A 3D Sub-Surface Characterisation of the Arnager Greensand, South-west Skåne

Abstract:  A surface characterisation of the Arnager Greensand in south Sweden, a deep saline aquifer found to be suitable for geological storage of CO2 or energy storage, was undertaken in this thesis. Vintage seismic reflection data only available as scanned tiff images of the final stacked sections were digitized and processed using modern interpretation software to provide new insights into the morphology of the Arnager Greensand and to analyse the reservoir’s potential as an energy storage unit. The primary energy storage method discussed and evaluated was Compressed Air Energy Storage (CAES). This is a modern energy storage method developed as a tool for regulating inherently intermittent renewable energy sources. Such methods are key to the growth of the renewable sector and for providing a competitive alternative to fossil fuels. Moreover, in comparison with other energy storage methods such as battery storage, CAES is known to have strong potential to deliver highperformance energy storage at large scales for relatively low costs compared with any other solution. Previous studies conducted in the 1980’s by Swedegas produced a 2D isochrone surface map of the Arnager Greensand by hand interpolation methods utilizing analogue data collected by Oljeprospektering AB (OPAB, currently Svenska Petroleum). The Geological Survey of Sweden (SGU) has now transferred a vast amount of the historical OPAB dataset to modern digital format. This thesis contributes to those efforts and seeks to find new interpretations from the vintage data. A more comprehensive 3D model of the top of the Arnager Greensand employing the application of modern interpretation software was produced in this study. Strong similarities between morphology and dip-trend have been observed between the surface model generated in this report and the historical Swedegas isochrone surface map. Reservoir properties such as thickness, porosity and permeability gleaned from the earlier reports show the Arnager Greensand to exhibit excellent potential as a storage unit. Preliminary effective capacity estimates by Nordic CCS Competence centre show the Aranger Greensand to be one of the top three storage aquifers in Sweden. These positive appraisals highlight the need for a better characterization of the Aranger Greensand through data digitization and modern interpretation means. This thesis contributes to that endeavour.