COMPUTATIONAL DOMAIN

1. FLOW THROUGH FRACTURED ROCKS Department of Mechanical & Aeronautical Engineering t=250s t=195s t=115s t=70s (a) (b) (c) Kambiz Nazridoust and Goodarz Ahmadi Clarkson University, Potsdam, NY 13699-5727 http://www.clarkson.edu/fluidflow/kam/research/ ABSTRACT Single and multi-phase flows through rock fractures occur in various situations, such as transport of dissolved contaminants through geological strata, migration of dense non-aqueous phase liquids through fractured rocks, sequestration of carbon dioxide in brine-saturated strata, and oil recovery. The presence of fractures in a reservoir plays a major role in the fluid flow patterns and the fluids transport. In this study the Brazilian test technique was employed to induce an extensional fracture with dimensions of about in a layered Berea (calcite-cemented) sandstone sample. High-resolution X-ray micro-tomography (CT) imaging was used to determine the geometry of the fracture. A post-processing code was developed and used to computationally model the fracture geometry; Gambit mesh generator was then used to generate an unstructured grid of about 1,000,000 cells. Single-phase and two-phase flows through the fracture were studied using FLUENT™ code. The Volume of Fluid (VOF) model was employed for the case of two-phase flow. Flow patterns through the induced fracture were analyzed. In geological flow simulations, flow through fractures is often assumed to occur between parallel plates. The combination of CT imaging of real fractures and computational fluid dynamic simulations may contribute to a more realistic and accurate description of flow through fractured rocks. GOVERNING EQUATIONS Continuity: Momentum: Volume of Fluid (VOF): Comparisonof Ratios of the Estimated Pressure Loss Based on Parallel Plate Model to Those Computed from the Numerical Simulation FLOWFIELD SOLUTION Pressure Drop vs. Flow Rate for Sections (a)-(d) THREE DIMENSIONAL MODELING (IN PROGRESS) COMPUTATIONAL DOMAIN Velocity Magnitude Contours for Section (d) Velocity Vector Field for Section (d) Velocity Magnitude Contours for Section (d) for Different Flow Rates Velocity Vector Field for Section (d) for Different Flow Rates Three Dimensional Model for Fractures: (a) Water Velocity Magnitude Contours for Fracture 1 (b) Water Volume Fraction and Velocity Magnitude Contours for Fracture 2 (c) Volume Fraction of Air (left) and Water (right) CONCLUSIONS • Computer simulation technique was capable of capturing the features of the flow through fractures. • The simulation results were in qualitative agreement with the parallel plate model. • The calculated pressure drops were linearly proportional to the flow rates similar to Darcy’s law. • A significant portion of the fracture pressure drop occurred in the areas with smallest passage width. • The order of the magnitudes of the pressure in various sections of the fracture were consistent with the number of smallest passages that were present in those sections. Static Pressure Contours for Section (d) for Different Flow Rates Volume Fraction of Water in Water/Oil Flow for Some Instances Frequency Distributions vs. Passage Size of The Four Fracture Sections Studied