Enhanced Oil Recovery Potential in the Uinta Basin, Utah

Morgan, Craig¹ and Milind Deo^2
1Utah Geological Survey, Salt Lake City, UT
²University of Utah, Salt Lake City, UT

     The Eocene Green River Formation is a major oil producer in the Uinta Basin. Currently, water flooding is the only enhanced oil recovery (EOR) technique being used in the basin. The Red Wash/ Wonsits Valley and the Greater Monument Butte fields produce from the Green River Formation and are currently in water flood. Red Wash discovered in 1951, has an estimated ultimate recovery (EUR) of 106 MMBO, neighboring Wonsits Valley discovered in 1962, has an EUR of 48 MMBO, and Monument Butte, discovered in 1981, is still being developed. The three fields were developed on 40 acrespacing. In the Monument Butte Northeast unit (part of the Monument Butte field) the density of the well spacing was increased from 40-acre spacing to 20-acre (a 40-acre five-spot pattern). The greater well density is expected to increase the EUR from 8 % of original oil in place to 12 %.
     Chevron, in the 1980s, attempted pilot CO₂ floods at two locations in Wonsits Valley field and two locations in Red Wash field. The Red Wash locations had almost immediate breakthrough of CO₂. Work on the CO₂ floods was stopped due to the poor results at Red Wash and declining oil prices. The University of Utah is conducting a numerical simulation model for the Glen Bench field (a step out from Wonsits Valley field) and the Monument Butte Northeast unit to determine the potential increased recovery if the fields convert to CO₂ flood, most likely a water alternating gas flood.
     EOR has not been attempted in the Cedar Rim/Altamont/ Bluebell fields. This area is significantly deeper, has highly fractured reservoirs, and mostly does not have the well spacing density needed for conventional EOR. There is a tremendous volume of oil being left behind in this field complex that may require some innovative and unconventional EOR techniques.

AAPG Search and Discovery Article #90071 © 2007 AAPG Rocky Mountain Meeting, Snowbird, Utah