Low-BTU Gas in the Permian Chase Group in the Ryersee Field in Western Kansas: A Case History where Technology Creates a Marketable Commodity

Kansas Geological Survey
Open-file Report 2003-57

Development History

Six wells were drilled inthe area of the Ryersee Field prior to its discovery. The earliest well was drilled in NE SW 35-18S-21W during 1928-29. This exploratory well noted several Cherokee oil shows and tested Chase gas. All tests were non-commercial. The discovery well, Ryersee #1 (NW SE 35-18S-21W), was drilled in 1956 and had an IP of 197 BOPD from the Cherokee Group. The well also had shows in the Mississippian Osage. Since the discovery well, 120 wells have been drilled; with 72 being commercial producers. Today, 14 commercial producers are left. The Ryersee Field has produced approximately 1.3 million barrels of oil to date, with 13,000 barrels in 2002.

In 1990, American Warrior, Inc. (AWI) began drilling in the Ryersee Field and has since drilled 36 wells. Between 1990 and 1998 all wells were drilled as oil wells, but some of these wells were used to test the extent, quality, and volume of gas in the Permian Chase Group. By 1995 AWI had determined that significant reserves of high-nitrogen gas were trapped in the Chase Group on the Bazine anticline.

AWI considered ways to upgrade this low-BTU gas in the mid-1990s, however, the technology needed to do so on this relatively small scale was not available at this time. Gas from the Ryersee #1-2 well was instead used as fuel for engines powering pumping units. This enabled considerable savings in lifting costs. This well continues to produce gas for the engines. In 1999, AWI began to look at processes for removing nitrogen and helium from the gas. The advancement of the microcomputer had allowed the cryogenic process (formerly used only at large scales) to be adapted for a smaller 5000 MCF per day processing plant. Furthermore, the plant could be modified to capture the helium and refine it to 90%+ for market. The nitrogen would be vented to atmosphere and the remaining natural gas would have a BTU content of 965 and be sold by pipeline.

River City Engineering designed the nitrogen-removal plant and AWI committed to its construction in 1999. In the following 2 1/2 years AWI drilled 6 gas wells in the Ryersee Field and converted another 6 wells from oil to gas. AWI also drilled 15 gas wells in the Pabst Field northeast of the Ryersee Field. At present, AWI has 25 gas wells across the area. Flow tests indicate present production capacity is sufficient to supply the processing facility at a rate twice its designed flow rate.

The Ryersee gas will continue to be developed. AWI has also discovered Chase gas reserves 6 miles (10 km) southwest of the Ryersee Field and another company has discovered Chase gas 4 miles (6 km) beyond these discoveries. Both developments are on the Bazine Anticline. As production declines in current wells, more wells are anticipated to be drilled along the Bazine anticline to adequately supply the processing plant.

Ryersee Field Development Timeline (click on above image to see more detail)

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Last updated November 2003