Field and Laboratory Experience in Closed Fracture Acidizing the Lisburne Field, Prudhoe Bay, Alaska

Abstract

ABSTRACT This paper describes the laboratory and field work performed to understand and improve the stimulation of the fractured carbonate formation producing in the Lisburne Field, Prudhoe Bay, Alaska. Within the producing formations, the lower Wahoo intervals are low permeability, fractured dolomitic zones that produce poorly when compared to the higher permeability upper intervals. Past attempts to stimulate these intervals have included propped fracture techniques and standard acid fracture techniques. A laboratory study evaluated the effects that various acid systems have on Wahoo rock properties, the degree of permeability enhancement, and stability of acid fracture conductivity. Various acid fracturing techniques were also investigated to determine which technique and acid system created long-term fracture conductivity. The laboratory study indicated the optimal treatment would be obtained by using emulsified acid in a fracture acidizing treatment followed by a closed fracture acidizing stage using emulsified acid. The unique combination of this particular acidizing technique and acid system has increased productivity in the Lisburne Field. Complete documentation of the field work optimization program is included in this paper. Pressure buildup (PBU) analysis has indicated fracture half lengths are from 25–100 feet long and production spinner surveys have determined that lower intervals are contributing to production. To date, over 40 new and old wells have been stimulated using emulsified acid with the closed fracture acidizing technique. Significant increases in production and reserves are currently being seen from this program.