Characterizing tight-gas systems with production data: Wyoming, Utah, and Colorado

By:  and 
Edited by: Luis BaezKen Beeney, and Steve Sonnenberg



The study of produced fluids allows comparisons among tight-gas systems. This paper examines gas, oil, and water production data from vertical wells in 23 fields in five Rocky Mountain basins of the United States, mostly from wells completed before the year 2000. Average daily rates of gas, oil, and water production are determined two years and seven years after production begins in order to represent the interval in which gas production declines exponentially. In addition to the daily rates, results are also presented in terms of oil-to-gas and water-to-gas ratios, and in terms of the five-year decline in gas production rates and water-to-gas ratios. No attempt has been made to estimate the ultimate productivity of wells or fields. The ratio of gas production rates after seven years to gas production rates at two years is about one-half, with median ratios falling within a range of 0.4 to 0.6 in 16 fields. Oil-gas ratios show substantial variation among fields, ranging from dry gas (no oil) to wet gas to retrograde conditions. Among wells within fields, the oil-gas ratios vary by a factor of three to thirty, with the exception of the Lance Formation in Jonah and Pinedale fields, where the oil-gas ratios vary by less than a factor of two. One field produces water-free gas and a large fraction of wells in two other fields produce water-free gas, but most fields have water-gas ratios greater than 1 bbl/mmcf—greater than can be attributed to water dissolved in gas in the reservoir— and as high as 100 bbl/mmcf. The median water-gas ratio for fields increases moderately with time, but in individual wells water influx relative to gas is erratic, increasing greatly with time in many wells while remaining constant or decreasing in others.

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Publication type Conference Paper
Publication Subtype Conference Paper
Title Characterizing tight-gas systems with production data: Wyoming, Utah, and Colorado
DOI 10.1190/urtec2013-086
Year Published 2013
Language English
Publisher Society of Exploration Geophysicists, American Association of Petroleum Geologists, Society of Petroleum Engineers
Contributing office(s) Central Energy Resources Science Center
Description 18 p.
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title Unconventional Resources Technology Conference, Denver, Colorado, 12-14 August 2013
First page 814
Last page 831
Country United States
State Colorado;Utah;Wyoming
Other Geospatial Rocky Mountains
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