Oil production dominates in Nebraska's Dundy County

Raymond R. Burchett
Nebraska Geological Survey
Lincoln

Dundy County, in southwestern Nebraska, covers about 920 sq miles in the Denver-Julesburg basin (Fig. 1 [148,638 bytes]). Since the discovery 1 Jones, in SE NW 21-1n-37w, in July 1957 by the James M. Cline Oil Co. that opened Jones field, about 385 wells have been drilled in the county.

As of Jan. 1, 1997, the county had 66 oil wells on production plus 11 wells temporarily abandoned or shut-in. The state had a total of 1,479 producing oil and gas wells at that time.

Seven wells were placed on production in the county in 1996, including two wildcats and five development wells. Nine dry holes were drilled during the year.

The county's 1996 drilling totaled 31,654 ft of exploratory hole and 50,746 ft in development wells.

Major reservoirs in the county include several carbonate zones of the Upper Pennsylvanian Lansing-Kansas City, Douglas, and Shawnee Groups and the Lower Permian Council Grove Group found at depths of 3,500-4,500 ft.

Minor gas volumes have been found in the Cretaceous Dakota Group in the northwestern part of the county, but they have all been shut-in or abandoned.

Cumulative production to July 1, 1997, exceeded 3.5 million bbl of oil from 69 wells, as reported by the Nebraska Oil & Gas Commission, and continued drilling activity plays an important part in the area's economy.

Geologic history

The geologic history of southwestern Nebraska is relatively simple, involving the effects of deposition over a broad basin shelf affected by minor uplifts related to the Cambridge arch.

No major faulting, folding, or thrusting is evident throughout the geologic section.

The origin of the anticlines associated with oil production is related to movement of the Cambridge arch with emphasis on folding rather than draping or faulting.

Structural movement has occurred throughout deposition of the sedimentary sequence.

Northeast-southwest trending anticline-syncline pairs developed during a phase of the Laramide orogeny, further enhancing structures already present.

Several major unconformities occur in the Early Paleozoic and Early Mesozoic. Cyclic sedimentation is dominant in the Pennsylvanian and somewhat dominant in the Permian sections.

A structural contour map (Fig. 1) on top of the Pennsylvanian Lansing-Kansas City Group (B zone) shows the relationship of the oil fields to the structure in Dundy County. Oil producing zones are shown on the electric log (Fig. 2 [110,438 bytes]).

The county's deepest penetration came in May 1961. The Donnell Drilling Co. 1 Daniels, in SW SW 27-3n-41w, went to total depth 5,587 ft and was a dry hole.

Drilling in recent years in southwestern Nebraska has resulted in the discovery of several new oil and gas fields.

Over the years these fields and others have grown, sometimes to encompass smaller fields.

Combined fields, field names, and locations can be found on the map. In recent times some production has been stimulated by waterflood, and both exploration and enhanced oil recovery will most likely continue for many years.

The Author

Raymond R. Burchett is a research geologist and professor with the Nebraska Geological Survey, a division of the University of Nebraska-Lincoln. He was a geologist during 1959-76 at the university and research geologist and professor during 1977-97, serving as chief of the geology section from 1987-90. He has BS and MS degrees in geology from the university.

Copyright 1997 Oil & Gas Journal. All Rights Reserved.