Advanced characterization of three-dimensional pores in coking sand by micro-CT

Coke formation is very important for in-situ oil combustion. Previous studies of the coke distribution and coke content for in-situ combustion have used two-dimensional surface observations and macro parameter measurements that cannot accurately describe the mechanisms for the burning of heavy oil which limits the accuracy of numerical simulations. X-ray microtomography (micro-CT) has been used as a non-destructive technique to characterize the material's microstructure for petroleum geology. This paper describes micro-CT measurements of coking sand samples in a laboratory to reconstruct three dimensional pore scale images. These measurements give relatively high contrast gray scale images with the watershed segmentation method and the Chen-Vese model algorithm used to construct the three dimensional images of the pores coke or in sand. The images are verified against data from TGA and densitometer measurements with good agreement. This method provides excellent models for analyzing the coke content, the relationship between the porosity and the coking content, and even for porous media fluid flow simulations of in-situ combustion.