(363f) Development of CFD-Based Simulation Tools for in-Situ Thermal Processing of Oil Shale/Sands

In-situ technologies are currently being explored because of their potential for reducing the environmental footprint of oil shale/sands development. However, the first generation technologies have proven to be energy-intensive, and many unknowns remain relative to optimal heating strategies, potential contamination of groundwater, and achievable production rates.

Reservoir simulation tools are typically applied to in-situ production processes. However, we are simulating a modified in-situ process where a distribution of rock size and orientation (important due to directional permeability of the rock) exists in the production bed. The rocks are heated by convective currents through the channels of the rubblized bed. Our approach is to apply CFD-based simulation tools to this modified in-situ process. The system consists of a clay-lined volume filled with rubblized oil shale that is heated by pipes fired with natural gas burners. We have employed a suite of commercial software tools, including EDEM, Matlab, Gambit, and Star-CCM+.

We have determined that a simulation with the actual geometry of the pieces of shale will provide more accurate results than treating the rubblized shale volume as a continuum with a defined permeability. DEM Solutions product, EDEM, a discrete element modeling software that is used for modeling particle movement, was used to simulate the filling of an empty bed with pieces of oil shale. This simulation models the interactions between particles and geometry as they fall into the bed. The simulation resulted in a bed full of thousands of pieces of oil shale that can be used as a representation of the actual rubblized bed. The EDEM simulation provides data about the position, size, and rotation of each particle.

Matlab was then used to write a journal file that defines the three-dimensional layout of the particles. The journal file was run in the CAD software Gambit to create the shale geometry. Gambit produces a parasolid transmit file which is a standard geometry file type that can be used in Star-CCM+. Implementation of the correct geometry representation in Star-CCM+ requires being able to represent boundary interfaces between pieces of shale and fluid.

We demonstrate the efficacy of this set of tools for the rubblized shale system, using the tools of validation and uncertainty quantification to perform a consistency analysis between simulation results and experimental data.