Constant-Internal-Phase Design Improves Stimulation Results

Abstract

Summary For several years, foam fracturing has been an excellent technique for stimulating low-pressure reservoirs. Conventional foam treatments, however, have been inconsistent in placing high sand concentrations and often reached a pressure limitation, which prematurely terminated the treatment. A new design approach to foam fracturing, the constant-internal-phase technique, has overcome previous sand limitations and has allowed treatments to be pumped with less severe pressure fluctuations. This approach treats all internal phases (gas, liquid, or solid) the same and recognizes the similarities in behavior among foams, emulsions, and slurries. A fluid's bulk viscosity increases as the total internal-phase fraction increases, particularly at high internal-phase ratios. The constant-internal-phase approach has produced more predictable wellhead treating pressures (WHTP's), used less hydraulic horsepower, and virtually eliminated premature job termination owing to pressure limitations.