Abstract

The Double Eagle Federal Unit is located on the northeast limb of the Gypsum Valley salt anticline in T44N, R16–17W, San Miguel County, Colorado. The Unit is at the west end of Andy’s Mesa Field where gas is trapped in upturned Pennsylvanian and Permian beds truncated by the northeastern salt wall of the Gypsum Valley anticline. Adjacent to the salt wall, lower Cutler, Honaker Trail and upper Paradox strata are cut by numerous strike-oriented antithetic and synthetic faults. These faults are oriented sub-parallel to the salt wall and compartmentalize the field. The Andy’s Mesa and Double Eagle hydrocarbon accumulation is divided by a keystone graben oriented perpendicular to the axis of the anticline. Through December of 2007, 34.4 bcf gas and 45 m bbls of condensate has been produced from the unit.

Between the Gypsum Valley and Paradox Valley salt anticlines, the Honaker Trail Formation conformably overlies the Paradox Formation and is conformably overlain by the Cutler Group. Most of the gas is produced from sandstones of the Honaker Trail Formation, with lesser contributions from arkosic sandstone in the lower Cutler Group and carbonates in the Ismay Member of the Paradox Formation. Productive sandstones have 14% - 17% porosity and a minimum of 4 ohm-meters of resistivity. Reservoirs are under-pressured, with gradients ranging from 0.35 to 0.38 psi/ft. The best Honaker Trail wells produce from multiple reservoirs located at the structurally highest part of Double Eagle Unit on the west side of the keystone graben. The up-dip seal for the field is salt and other evaporites. Vertically, gas is sealed by shales and carbonates within the Honaker Trail and by shale in the Cutler Group. Faults parallel to and perpendicular to the salt wall are local barriers that act as boundaries to structural compartments.