State-of-the-art technology in rock mechanics, fracture mechanics, reservoir engineering and formation evaluation was effectively applied to enhance gas production from a tight gas sand field in Sublette County, Wyoming. Previous attempts at production from this field were not successful due to low initial flow rates and rapid production declines mostly associated with low permeability of the formation. Two research wells were drilled to 12,000 foot depths and a systematic approach towards their completion by hydraulic fracturing was taken by means of associated laboratory, field, and analytic tasks. Laboratory tests on core materials were carried out at appropriate in-situ conditions which resulted in the use of suitable fracturing fluids that caused minimum damage to the matrix permeability and fracture conductivity. Water-base fracturing fluids with high pH (≃8.0) values were recommended for the sand zones investigated. In-situ stress measurements were also taken in and around the selected pay zones. Proper and cost effective proppants were used and strict quality control procedures were imposed during the stimulations.
One zone in each well was successfully fractured. Prestimulation initial production of 107 MCFD for the first well was increased to a post-stimulation value of 4,150 MCFD while the second well was increased from 35 MCFD to 1,450 MCFD. Long-term deliverability projections were made by history matching post-stimulation production and build-up test data.
Presently, the obtaining of ten months of continuous production data from the two research wells is ongoing. A unique trucking procedure to transport the produced gas to a somewhat distant transmission line is emphasized in this case history discussion.