3-dimensional computer model to simulate fluid flow and contaminant transport through a rock fracture system

A 3-dimensional fracture generating scheme is presented which can be used to simulate water flow and contaminant (solute) transport through fracture system of a rock. It is presently limited to water saturated conditions, zero permeability for the rock matrix, and steady state water flow, but allows for transient solute transport. The scheme creates finite planar plates of uniform thickness which represent fractures in 3-dimensional space. A given fracture (plate) has the following descriptors: center location, orientation, shape, areal extent and aperture. Each parameter can be described by an appropriate probability distribution. Individual fractures are generated to form an assemblage of a certain fracture density. All fracture intersections and boundary/fracture intersections are determined and deadend fractures are eliminated. Flow through the fracture assemblage is considered laminar and described by Poiseuille's law. The principle of mass conservation at each intersection is used to develop the global matrix equation, which is solved subject to specified boundary conditions to yield the head and flow distribution at each intersection. Solute transport is considered to be advective between intersections with complete mixing at each intersection. Solutes added to the flow system can be explicitly followed and concentration vs. time relationships can be determined anywhere in the system. Some examples are included