Tripled gas rates with multi-stage fracs and increased frac size in this ~1500 ft. deep reservoir. Much improved rates were observed with larger 12/20 sand, despite modeling suggesting 20/40 would be adequate. Success achieved with 10-12 ppg slugs and intentional screenouts according to interviews with authors.
In 1996, Williston Basin Interstate Pipeline Company (WBI), a wholly owned subsidiary of MDU Resources Group, Inc., implemented a pilot program to improve production from the Eagle Gas Sands in Southeastern Montana. The program included running Formation Micro-ScannerTM Logs (FMS) logs to identify natural fractures and permeable pay intervals and using three-dimensional fracture modeling to determine the optimum fracture treatment size. By applying technologies and multi-stage fracture treatments, WBI has more than tripled gas production rates.
While the optimal completion program has yet to be determined, especially in the deeper (1700+ft) horizons, all wells drilled and completed in 1996 are producing gas. This 100 percent success ratio is a significant improvement over previous years when less than 60% of the wells responded to stimulation. A savings of $420,000 was realized in 1996 by eliminating the need to restimulate 50% of the wells. First year incremental NPV increased by 20% or $ 11,600 per well for the 24-well program in 1996. This equates to an incremental 10-year NPV of over $335,000 per well and over $8.8 million for the drilling program.
Author(s): T.W. Green, Halliburton Energy Services; D.M. Zander, Williston Basin Interstate Pipeline Co., S.A. Holditch & Assoc. Inc; M.R. Besler
Paper Number: SPE 38374