Numerical modeling of fluid and electrical currents through geometries based on synchrotron X-ray tomographic images of reservoir rocks using Avizo and COMSOL

The use of numerical simulations to model physical processes occurring within subvolumes of rock samples that have been characterized using advanced 3D imaging techniques is becoming increasingly common. Not only do these simulations allow for the determination of macroscopic properties like hydraulic permeability and electrical formation factor, but they also allow the user to visualize processes taking place at the pore scale and they allow for multiple different processes to be simulated on the same geometry. Most efforts to date have used specialized research software for the purpose of simulations. In this contribution, we outline the steps taken to use commercial software Avizo to transform a 3D synchrotron X-ray-derived tomographic image of a rock core sample to an STL (STereoLithography) file which can be imported into the commercial multiphysics modeling package COMSOL. We demonstrate that the use of COMSOL to perform fluid and electrical current flow simulations through the pore spaces. The permeability and electrical formation factor of the sample are calculated and compared with laboratory-derived values and benchmark calculations. Although the simulation domains that we were able to model on a desk top computer were significantly smaller than representative elementary volumes, and we were able to establish Kozeny-Carman and Archie's Law trends on which laboratory measurements and previous benchmark solutions fall. The rock core samples include a Fountainebleau sandstone used for benchmarking and a marly dolostone sampled from a well in the Weyburn oil field of southeastern Saskatchewan, Canada. Such carbonates are known to have complicated pore structures compared with sandstones, yet we are able to calculate reasonable macroscopic properties. We discuss the computing resources required. Graphical abstractStreamlines of simulated fluid flow through pore spaces of a carbonate rock imaged with synchrotron X-ray tomography. Colors indicate the magnitude of the flow velocity.Display Omitted HighlightsAvizo and Comsol are used to segment pore space and model fluid and electrical flows in rock pores.Pores are extracted from a synchrotron X-ray tomographic image of a carbonate rock core.Permeabilities and electrical formation factors agree with lab measurements and benchmarks.We describe the processing steps taken and the required computer resources.