Project Rulison was designed to use underground nuclear technology to determine the potential of this technique for commercial development of the deep, thick, lenticular, low permeability Mesaverde Formation of the Rulison Field in Garfield County, Colorado. A method of stimulation, far greater in magnitude and efficiency than conventional hydraulic fracturing, is needed to recover this gas at economic rates. The Project Rulison exploratory well, R-EX, was completed in May, 1968. Detailed testing of this well provided data on geology, hydrology and reservoir characteristics. The data obtained from the testing have been used to determine the flow capacity of the Mesaverde reservoir. The reservoir characteristics were then used as input data to make predictions of post-shot reservoir performance in the nuclear stimulated well. A nuclear explosive with a design yield of 40 kilotons was emplaced in a 10-3/4" hole at a depth of 8426' below ground surface and detonated on September 10, 1969. Appraisal of the data taken at shot time indicate that the explosive behaved as predicted. The explosion was completely contained underground as predicted and no major seismic damage occurred. The post-shot drilling program, to re-enter the chimney, and test program, to determine the degree of reservoir stimulation achieved, are discussed. Data taken during the initial phases of the post-shot re-entry and evaluation phase will be given.

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