The Niobrara Gas Play: Exploration and Development of a Low-Pressure, Low-Permeability Gas Reservoir

Abstract

Summary The Niobrara gas play in eastern Colorado, northwestern Kansas, and western Nebraska is a successful economic development involving an integrated, interdisciplinary exploration and exploitation strategy. This comprehensive study of the Niobrara formation gives a concise description of methods for exploration, development, production and evaluation of the Niobrara reservoirs. Introduction In 1912, the Osborne and Dunn Co. encountered a strong flow of gas in the Niobrara formation while drilling the Goodland No. 1 well (Sec. 24-T8S-R40W) near the town of Goodland, KS. The well subsequently was plugged and abandoned. In the 1930's and 1940's, several small Niobrara gas wells were drilled in the Goodland field area by Industrial Gas Co. and others for local use only. The Beecher Island field discovery well was Midfields No. 1 well (Sec. 14-T2S-R43W) in Yuma County, CO, drilled in 1919 by the Midfields Oil Co. It had estimated flow rates of up to 2 MMcf/D (57×10-3 m3/d) of gas. In the 1920's, four additional Niobrara wells were drilled in Beecher Island; however, connection to a pipeline could not be justified. By 1970, two of the four dry holes drilled to deeper formations had gas shows while penetrating the Niobrara formation. Following a study in 1972 of the known gas shows in the Beecher Island field, Midlands Gas Corp. and Mountain Petroleum Corp. air-drilled six wells in Beecher Island. Five were completed without stimulation as producers and then were connected to a pipeline. The wells averaged 20 Mcf/D (565 m /d) each, which at $0.35/Mcf ($0.35/30 m) was uneconomical. However, they proved the existence of significant gas reserves. Further investigation revealed many resistivity log anomalies and reported gas shows in the Niobrara of eastern Colorado and western Kansas. However, the play began when, in early 1974, the new high-quality foam fracture stimulation process was used for the completion of the Beecher Island field State 1-29 well (Sec. 29-T2S-R42W). The well had a prestimulation drillstem test rate of only 5.6 Mcf/D (160 m3/d). After the treatment, it had an initial potential of 721 Mcf/D (20×10 M /d), with a sustained rate of more than 150 Mcf/D (4250 m3/d). The play now extends from Chadron, NE, and south to Kit Carson County, CO (Fig. 1). The major concentration of drilling remains in the original producing area in Yuma County, CO, and in Cheyenne and Sherman counties, KS. Since 1974, 919 Niobrara wells have been drilled, of which 454 are producers in more than 60 fields; 465 wells are dry holes. At this time, very few fields are developed fully. Geology and Gas Origin The Niobrara formation chalks were deposited during the last major transgression of the western interior Cretaceous sea, which extended from the Gulf of Mexico to the Arctic Ocean. The lower member of the Niobrara is the Fort Hays, which is 40 to 85 ft (12 to 25 m) thick. The upper member is the Smoky Hill, which averages 600 ft (180 m) (Fig. 2). JPT P. 2863^