Paper: Fracturing Poorly Consolidated Sandstone Formations

The A & B zones of the Trading Bay Oil Field, Cook Inlet, Alaska are a series of heterogeneous, largely unconsolidated sandstones. These sands contain several million barrels of reserves. Although numerous attempts had been made to produce these zones since 1967, less than 1% of the oil-in-place had been produced by January, 1980. Wells which were completed in the A & B intervals typically tested at non-commercial producing rates or declined to uneconomic rates within a year. Re-perforating, acidizing and various flushes with oil, all proved unsuccessful. Extensive analysis and studies of reservoir fluids, core material and production characteristics resulted in isolating the cause of the producing problems as a formation fines movement problem. Use of various clay stabilizing chemicals met with no success. Conventional formation fracturing to stimulate production appeared to be out of the question because of the problems of proppant imbedment in the soft, dirty sandstones. However, a concept to fully pack created hydraulic fractures with high concentrations of proppant and modifications of conventional fracturing procedures to achieve it, appeared promising, was pursued, and found to be successful. This paper describes a fracturing technique including procedures and materials for poorly consolidated sandstones. The stimulation technique has resulted in successful completions in the A & B zones and made possible economic recovery of a significant and heretofore essentially non-producible resource. It is expected that the technique may be applicable in many other areas where economical drainage of oil deposits from poorly consolidated sandstones is presently not possible.