The Codell sandstone in the Denver-Julesburg Basin is a low permeability, clay-rich sandstone. It is bounded by the Ft. Hays limestone member of the Niobrara formation above and shales of the Carlile formation below. The Codell requires stimulation by hydraulic fracturing in order to produce at economic rates; however, some stimulation procedures are not effective.

Analysis of the less successful treatments indicated that inadequate fracture length and conductivity were common problems. Formation properties, gathered in situ, were used in a 3-D fracture design simulator to predict fracture growth in the Codell and bounding formations. Published laboratory data has proven that low proppant conductivities are associated with low proppant concentrations and imply that the use of high concentrations should improve conductivity. In addition, greater initial rates and sustained long-term Codell production support the use of high proppant concentration treatments.

This paper will present a history of treatments and changes which led to more effective stimulation of the Codell formation in the Denver-Julesburg Basin. Comparative production data will show the benefits of this improved treatment design.

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