Gas-water displacement through fracture networks

This study is focused on gas-water displacement through fracture networks. First, we investigated the flow patterns in fracture branches following a f racture intersection. Laboratory experiments were conducted to qualitativel y identify the gas-water flow patterns in intersecting fractures. A mathema tical model consistent with the actual phenomena observed in the laboratory was then formulated. The mathematical model is represented by a nonlinear system of partial differential equations, which is solved by an iterative n umerical method. In the second part of the study, investigations of a verti cal cross section of a fracture network were conducted. Two sets of fractur es were assumed to intersect orthogonally, as characteristic of some granit es. The angles of the fractures with the horizontal direction were either 4 5 degrees or 135 degrees. Fracture intersection centers, fracture lengths, and fracture openings were generated according to statistical distributions . Simulations were carried out under constant pressure boundary conditions at top and bottom as might be found at offshore radioactive repositories. T he present study, which accounts for a gas-water slug, shows that the flow of water reaches quasi-steady state with continuous gas release.