This paper summarizes the design changes in the first 300 fracture stimulations performed at Kuparuk. Standard treatments consisting of 20/40 frac sand increased unstimulated rates by 300%. 12/20 sand was attempted, with larger pad volumes and addition of 100 mesh sand. Results with 12/20 sand were disappointing. Subsequent SPE papers document the following progression to larger ceramic proppants with outstanding success.
Sixty-five percent of the proven reserves in one of the United States' largest oil fields, the Kuparuk River Unit, are contained in the lower of two producing horizons. This zone, commonly referred to producing horizons. This zone, commonly referred to as the "A" sand, has a permeability of between 30 and 100 md. Unfortunately this interval is easily damaged during drilling and completion operations. Low initial flow efficiencies have been confirmed by numerous pressure transient tests. A program of hydraulic fracturing was initiated in March 1984 to overcome near wellbore damage and provide stimulation to more efficiently tap "A" sand reserves.
More than 300 fracture stimulations have been completed to date in the arctic setting of the Kuparuk River Unit. These jobs have used a variety of fluids, proppants, and pumping schedules. The current hydraulic fracture design was evolved by continual interpretation of field results and related data from these previous stimulations. Success of the overall program has been impressive. Average post-fracture flow efficiency has been in excess of post-fracture flow efficiency has been in excess of 100%. Post-fracture rate increase has averaged approximately 300%, accounting for a total rate increase of over 125,000 BOPD (19,900 m3/d). Based on these results, fracturing will continue to play an important part in future field development.
This paper is the first review of the Kuparuk River Unit fracture program. It provides a case history of the development of a standard fracture design. In addition, the findings of this study would be applicable to reservoirs elsewhere with similar characteristics.
Author(s): ARCO Alaska Inc., B.L. Niemeyer, M.R. Reinart
Paper Number: SPE 15507