DARCY FLOW TO A VERTICAL FRACTURE INTERSECTING A CYLINDRICAL CAVITY-APPLICATION TO WATER PERMEATION IN UCG.

Several in situ processes involve flow through porous media to a sink with complex geometry described approximately by a vertical cylinder attached at the side to a very thin slit; for example, a single fracture which intersects a well bore. Laplace's equation for this case is solved exactly through three successive conformal mappings. The flow rate to the cylinder and the slit is cast into a simple form requiring the transformation of only a single point, thus circumventing the need to transform the entire original boundaries. This analysis is applied to a prediction of water influx by permeation into the cavity-link geometry found in underground coal gasification. This permits determination of the effect of water influx on process chemistry.