Paper: The Use of Alcohol-Water Mixtures In Fracture Stimulation Of Gas Wells

In recent times, a tremendous amount of effort has gone into the development on nonaqueous fracturing fluids. These fluids, usually alcohol or high-gravity hydrocarbons, which may contain propane, carbon dioxide or nitrogen, have been utilized in the stimulation of many formations. The above systems, while normally being successful, have some shortcomings. Generally the fluids are expensive and many require specialized equipment. With the introduction of a new fracturing fluid based on mixtures of alcohol and water, a lower cost alternative is now available. The alcohol-water systems are particually applicable in low-porosity, low-permeability gas reservoirs. Laboratory tests with formation cores show that the effective permeability to gas following injection of alcohol solutions is much more rapid than when water is the injected fluid. These fluids, which can contain from 20 to 40% methanol, also aid in protecting water-sensitive formations against clay swelling and migration. In addition, the presence of alcohol markedly reduced the surface tension of the fluid. These advantages permit rapid production fo the fracturing fluid from the formation. Many field tests have shown that rapid cleanup is obtained with this system. This paper presents a description of the fluid system, various viscosities that may be obtained, including crosslinked or delayed gels, as well as laboratory field results.