Upscaling relative permeability and capillary pressure from digital core analysis in Otway formation: Considering the order and size effects of facies

Abstract

Digital Core Analysis (DCA) has emerged as a crucial instrument in reservoir characterization in recent times. With the advent of high-resolution micro-CT imaging, it is now possible to visualize the three-dimensional microstructures of in-situ pores and flow patterns within rocks. DCA offers several notable benefits over traditional techniques, such as a higher density of measurements, faster processing times, and the preservation of rock samples. It also demonstrates considerable flexibility with challenging core conditions and can derive numerous parameters from each individual sample. The objective of this work is to utilise DCA data from Otway formation to enhance reservoir characterisation and CO2 plume forecast. However, a critical challenge is that these data are obtained at a micro-scale, necessitating an upscaling of DCA properties from the micro-scale to core scale, and subsequently to the site and field scale, for compatibility with reservoir simulation and field studies. This study proposes an implicit and iterative method to upscale DCA properties and explore the impact of facies order and size on the upscaling process of relative permeability and capillary pressure. This method is implemented in an open-source simulator known as the Matlab Reservoir Simulation Toolbox (MRST). The findings indicate that relative permeability and capillary pressure outcomes from upscaling are influenced by order and portion of facies. This highlights the importance of considering both the size and arrangement of facies during the upscaling process, given their potential impact on fluid dynamics and the accuracy of reservoir simulation results.