This report describes the work performed during the second year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on modeling the fluid flow in fracture surface, examining the fluid transfer mechanisms and describing the fracture aperture distribution under different overburden pressure using X-ray CT scanner.

The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. This report provides results of the third semi-annual technical progress report that consists of application of X-Ray Tomography results to validate our numerical modeling of flow in fractures. Spontaneous imbibition plays a very important role in the displacement mechanism of non-wetting fluid in naturally fractured reservoirs. To quantify this spontaneous imbibition process, we developed a 2D two-phase numerical model. This numerical model was developed because an available commercial simulator cannot be used to model small-scale experiments with different boundary conditions. In building the numerical model, we started with the basic equation of fluid flow and developed a numerical approach of solving the non-linear diffusion saturation equation. We compared our numerical model with the analytical solution of this equation to ascertain the limitations of the assumptions used to arrive at that solution. The unique aspect of this paper is that we validated our model with X-ray computerized tomography (CT) experimental data from a different spontaneous imbibition experiment, …