A Fundamental Approach to the Simulation of Flow and Dispersion in FracturedMedia

Abstract

Fracture systems may be generalized in terms of number and orientation of sets of parallel fractures and the distribution of length, width, thickness and separation. Borehole measurements may be used to particularize these parameters for a specific site. Global flow anddispersion in an aquifer occur in the interconnected fractures and may be related to specific fracture elements. A fluid dynamics code named SALE has been used to solve the Navier-Stokes equations for laminar flow in these elemental geometries. A marker particle calculation has been added to characterize longitudinal dispersion due to the velocity profile across the fracture and lateral dispersion due to flow disturbances at junctions. Local flow and dispersion in the matrix occur in the fine r fractur e structure and are evaluated using porous media approaches. These results o r models are integrated in a 20 i sothermal reservoir simulator named FRACSL. Discrete frac t u r e s are superimposed on the edges or diagonals of rectangular grid elements. Water mayflow from node tonode through the matrix or through the fracture. The heads are found by i t e rating for the d is t r i bution whicii cor!serves the appropriate local mass. Mar:<:?: p z r t i c l e s are used to monitor the tracer dispersion due to notion in the fractures, in then a x r i x and between the two. Results are given showing flow and dispersion in an orthogonal junction and in a sample fractured reservoir .