This paper was prepared for the Rocky Mountain Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in Casper, Wyoming, May 15–16, 1973. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract

Between October 1969 and November 1970, the Wagon Wheel No. 1 well was drilled to a total depth of 19,000 feet. Its purposes were (i) exploration to greater depths than penetrated by the ten previously drilled wells in the Pinedale Unit and (ii) providing detailed reservoir and rock property data essential to evaluation of nuclear property data essential to evaluation of nuclear stimulation.

Methods used to estimate a cumulative total of 252 Bcf of gas in place per section in intervals with a water saturation less than the 60 percent and to establish permeability of 0.0034 md for those net pay intervals will be described. pay intervals will be described. Permeability distribution following nuclear detonations was predicted by correlating the permeability change deduced from Gasbuggy production permeability change deduced from Gasbuggy production tests with calculation of explosion effect upon reservoir rock at the Gasbuggy and Wagon Wheel locations. For a 100 kiloton nuclear detonation yield at a depth of 10,000 feet at the Wagon Wheel location, permeability is expected to be very large to a radius permeability is expected to be very large to a radius of about 105 feet, increased more than a factor of two to the limit of shear fracturing at a radius of 220 feet, slightly increased to the limit of tensile fracturing at a radius of 440 feet and unchanged beyond 440 feet.

Economic analysis based on wells with a 2,700 foot interval stimulated using five sequentially detonated explosives, has revealed a potential wellhead price of about 60 cents per Mcf. Cost estimates for this analysis include generous allowances to assure public safety, protect the environment and produce gas containing steam at an estimated temperature produce gas containing steam at an estimated temperature of 600 degrees Fahrenheit.

Introduction

The Pinedale anticline is about 30 to 40 miles long and 5 to 6 miles wide and parallels the western flank of the Wind River Mountains in Sublette County, Wyoming. It was formed by the Wind River Uplift to the east and the Wyoming Overthrust Belt to the west moving toward one another during Laramide time. The upper 7,000 feet consists of Eocene arkose sediments which are water-bearing and head measurements have shown the shallowest and deepest equifers are not hydraulically connected. Paleocene Fort Union and Cretaceous sediments are cut by a fault which has approximately 600 feet of stratigraphic displacement at the west flank of the Pinedale anticline. With increasing depth, the fault plane curves toward Wind River Uplift and ultimately becomes parallel to the bedding planes at a depth of approximately 30,000 feet.

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