"A good well field design often determines the success of on in-situ oil shale mining project. A successful well field design should consider the following essential parameters: 1. Three dimensional geohydrologic properties of the reservoir 2. Sweep efficiency of well field pattern 3. Well spacing 4. Breakthrough time and production projection The three dimensional geohydrologic properties of ,a reservoir are vertical and horizontal permeability's, leakage. storage coefficient, and vertical and horizontal boundary conditions. These geohydrologic properties can be tested in a single field test program. these properties will provide overall mass balance and fluid flow control parameters of the in-situ oil shale mining operation. The sweep efficiency of a well field pattern is a key design parameter . For isotropic conditions, a standard 5-spot pattern is preferred. For anisotropic conditions, direct line drive, staggered line drive, and marching line drive patterns are preferred. Basically. well field design patterns that can provide maximum well spacing, symmetrical sweep with least dilution and excursion are considered to be acceptable."