The Canyon Creek and Trail fields in southwestern Wyoming have produced gas for more than 70 yr. During that time, development progressed from amalgamated fluvial sandstone reservoirs of the Ericson Formation to the tight-gas sandstone reservoirs of the Almond Formation. Development of the Almond Formation reservoirs was attended by increasing variability in well results, which, in conjunction with a decade of low gas prices, necessitated a higher-resolution predictive framework for development. Viewing the Almond results through an unconventional or basin-centered gas lens led to dividing the areas of the field into favorable (sweet spots) or unfavorable, a generally low-resolution interpretation. This paper details a case study of the Almond Formation reservoirs where the tight-gas accumulation is placed in a petroleum system framework and evaluated with conventional petroleum assessment tools. The tight nature of the Almond Formation accumulation can be adequately delineated, and a predictive model of sweet spot locations and extent generated when structural evolution (paleostructure) and reservoir quality degradation is incorporated, along with reservoir architecture, original reservoir quality, source kitchen areas, and migration paths. Using conventional assessment tools and an understanding of how the accumulation evolved from a conventional gas accumulation in the geologic past to a tight gas accumulation today, this paper details a predictive model for the Almond reservoir sweet spots in the Canyon Creek and Trail fields. These techniques and concepts can be applied to any tight accumulation where the overprint of hydrocarbon migration, structural evolution, and reservoir degradation are operative.

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