The massive Hugoton natural gas field that straddles the southwestern edge of Kansas and northern Oklahoma has been in decline for the past 10 years, but a study by the Kansas Geological Survey (KGS) at the University of Kansas indicates that the gas still in place could be extended through 2050, provided the integrity of 40- to 70-year-old wells is maintained.

Previous studies have been published on the Hugoton and its sister reservoir the Panoma, but the new study is the first comprehensive report that covers the entire Kansas and Oklahoma Hugoton gas area and its many geologic layers. The study's findings also may be used to study similar gas reservoirs worldwide.

"Importance of the Hugoton field study extends beyond the borders of Kansas and Oklahoma," said KGS's Martin K. Dubois, one of six co-authors. "Both the knowledge gained and the techniques employed have implications for understanding and modeling reservoir systems worldwide that have similar geologic age, reservoir architecture, production characteristics, problems in determining water saturation, large data sets, multiple operators or state of maturity.

"As the world's giant fields mature, high-resolution modeling at the full-field scale in data-rich environments will become increasingly important."

The two-year collaborative study brought together KGS researchers and nine industry partners: Anadarko Petroleum Corp., BP America Production Co., ConocoPhillips, Cimarex Energy Co., EOG Resources Inc., ExxonMobil Corp., Medicine Bow Energy Corp. (now El Paso Exploration & Production), Osborn Heirs Co., OXY USA Inc. and Pioneer Natural Resources USA Inc.

"Working together with the oil and gas industry, we are able to make the best use of our natural resources," said co-author Alan Byrnes. "A lot of the information our industry partners provided, such as core and pressure data, was previously not available. Having it was absolutely critical."

The study confirmed what KGS had estimated, that 65% of the field's gas, or 35 Tcf from about 12,000 wells, already has been removed from the field since its discovery in 1922. In the 1960s, the field regularly produced 600 Bcf a year. In 2006 the Hugoton field produced about 250 Bcf.

Dubois said the "next step is to determine how to do a better job of producing" the gas.

"Production appears likely to be sustainable, provided the integrity of 40- to 70-year-old wells can be maintained," the report concluded. Production projected to 2050 in the 28 model wells "suggests that most of the additional gas recovered (21.3 Bcf) is primarily from zones having lower permeability," with the average well production estimated to be 21 Mcf/d/well with a decline rate of less than 2%.

The report is available at www.kgs.ku.edu//PRS/publication/2007/OFR07_06/index.html.

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