The U.S. Department of Energy's (DOE) Morgantown Energy Technology Center has performed an extensive reservoir simulation study on gas production from tight gas sands in the Rulison Field area of the Piceance Basin in western Colorado. Production behavior was modeled for the low permeability gas sands of both the Wasatch Formation and the lenticular portion of the Mesaverde Group. The study forecasted total gas production for Township 6S, Range 94W for 25 years, based on current well spacing regulations (160 acres [6.5 x 105m2] for Wasatch wells, 320 acres [1.3 x 106m2] for Mesaverde wells). The study also predicted the effects on gas recovery of reducing the well spacing to 80 acres (3.2 x 105m2) and 160 acres (6.5 x 105m2) for the Wasatch and Mesaverde, respectively. The reservoir study utilized a dual porosity, single-phase gas simulator to characterize reservoir behavior by history matching actual production performance from 23 Wasatch and 12 Mesaverde wells in the Rulison Field.
The study followed two extensive DOE field testing programs, a multiwell experiment and a special Mesaverde test well drilled in Naval Oil Shale Reserve No. 3. These DOE field tests provided geologic information and values for reservoir parameters that control production from this unconventional gas resource. In addition to the results from the two field experiments, the study used a detailed geologic analysis to help characterize the producing formations.