seals can be attained the purpose of the evaluation wells is to obtain useful information about the overburden and the coal deposit without having to drill all of the wells in the selected well pattern used for production preferably the evaluation wells will be drilled and completed in such a manner that they may be used as production wells later in the production program wells used in production should be suitably equipped to permit injection of fluids into the coal seam and to withdraw products of reaction from the reaction zone during the course of drilling the evaluation wells it is desirable to take cores in the overburden immediately above the coal seam such cores are then examined and tested with the resulting data used to predict expected roof falls and subsidence when the evaluation well reaches the coal seam it is preferable that oriented cores be taken through the coal seam such cores are then examined and tested with the resulting data used to determine the prevailing directions of maximum paths of permeability and the general permeability of the coal itself preferably the next step is to test the coal seam for its free water content this can be done by placing a pump at the bottom of the seam and withdrawing water to the surface of the earth until the water table in the immediate vicinity of the well bore is lowered to the bottom of the seam the well then is preferably shut in for a.