Drawdown Distribution around Large Diameter Well in Double Porosity Medium

Naturally fractured rock is idealized as a double porosity medium which is composed of homogeneous fractures and blocks. The groundwater flow is Darcian toward a fully penetrating large diameter well, from which the water is withdrawn at a constant rate. For such a configuration of well and flow characteristics, the necessary continuity expressions are written for the blocks and fractures separately in addition to the fracture as well as the block-to-fracture flow laws. The combination of these expressions and solution of the resulting partial differential equation by means of Boltzmann transformations lead to type curve expressions, which give the drawdown variations with time. These curves have initial straight line portions that are steeper than a singly porous medium case and therefore indicate the natural fracturation within the aquifer. The application of the derived type curves is shown through matching a procedure to actual field data.