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Kansas Geological Survey, Open-file Report 88-39
Great Plains and Cedar Hills Aquifers--Page 22 of 25

8.0 Water use from the Great Plains Aquifer and Shallow Disposal of Oil-field Brines

8.1 Water Use from the Great Plains Aquifer

The Great Plains aquifer is used for municipal, domestic, and stock use throughout the study area. The principal aquifer tapped by these water supplies is the Dakota Formation (upper part of the Great Plains aquifer), where the dissolved solids and concentrations of other dissolved constituents are small enough to allow use of ground water from this unit. The area of most intensive use covers southern Ellis, Russell, and Trego counties, and northern Rush and Barton counties. Water from the Great Plains aquifer is used for municipal supply at LaCrosse (as a supplemental source), Liebenthal, McCracken (rural water district), and Loretta in northern Rush County and Claflin in Barton County; and for industrial use by Cities Service Gas Company at Otis. The total amount of water withdrawn for municipal supply from the Great Plains aquifer is approximately 50 acre-ft annually. During the course of the study, three oil-field water supply wells were located in Rooks and Graham counties that withdraw water from the Great Plains aquifer for use in secondary recovery operations.

8.2 Shallow Disposal of Oil-Field Brines

Shallow disposal of oil-field brines through injection wells has been practiced by the oil industry since the 1930's (Jewett and Butcher, 1957). Injection horizons in the lower part of the Dakota Formation in part of Russell County, the Cheyenne Sandstone and Cedar Hills Sandstone have been used since that time. During the early 1940's, the State Board of Health allowed disposal of oil-field brines into the lower part of the Dakota for a brief time (Bill Bryson, personal communication, 1987).

At present the Cedar Hills Sandstone is the only injection horizon being approved for shallow disposal by the KCC. Approximately 460 Cedar Hills disposal wells are in operation in the study area and are field-checked periodically for injection pressures by the KCC (as of September 1987; Figure 20). During the period 1975-1983, the average rate of disposal was approximately 93,757,000 bbls (5035 acre-ft) per year in the study area or approximately 550 bbls per day per disposal well.

Disposal in the Cedar Hills Sandstone is generally done under "gravity flow" conditions (no additional injection pressures applied to the brines to induce movement into the formation). However, in northwestern Rush County and other locations where the static fluid levels in the Cedar Hills are above land surface, additional fluid pressures are required to move the brines from the well bore into the formation. Applied pressures measured at the well heads in this area range from less than 10 to more than 200 psig. In contrast, disposal of oil-field brines into the Cheyenne Sandstone was routinely done under conditions of applied pressure in order to cause the formation to accept the disposed brines. Applied pressures ranged up to 250 psig measured at the well head during injection. New injection wells have not been permitted to dispose into the Cheyenne since the early 1970's.

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Kansas Geological Survey, Dakota Project
Original document dated December, 1988
Electronic version placed online April 1996
Scientific comments to P. Allen Macfarlane
Web comments to webadmin@kgs.ku.edu