Gas Frac - A New Stimulation Technique Using Liquid Gases

Abstract

Abstract Gas Frac is a fracturing treatment using a new and absolutely water-free fluid system. The fluid is liquefied petroleum gas and liquid carbon dioxide mixed in such a ratio that they remain a liquid and behave as other liquids as long as they are under adequate pressure and below their critical temperature. After the fluid is heated to this temperature in the reservoir and pressure released, the liquid reverts to a gas. This results in extremely rapid clean-up and no residual fluids are left in the formation. Gas Frac was developed especially for gas well stimulation. Results to date have proved the technique to be very successful. This paper discusses the technique of Gas Frac and the materials and equipment used. analysis of results of treatments is presented. Introduction Many gas bearing reservoirs have resisted stimulation from conventional methods of liquid injection. Expected stimulation results often are totally or partially offset because of liquid retention by the reservoir. Core testing on many reservoir rocks, especially those with pore structures displaying a high surface area pore structures displaying a high surface area (pin point porosity), verifies this type of damage. Frequently, liquid retention damage was credited to water sensitivity when water, brine, or acid was used as the treating fluid. It is recognized that water sensitivity is a real problem and frequently adds to the complications problem and frequently adds to the complications associated with liquid retention. When oils were used in gas reservoirs with negative results, the problem was related to the creation of a third phase. Without becoming involved in the academic merits of classifying negative stimulation results according to the aforementioned problems, a new stimulation fluid has been created which can be useful in the prevention of liquid retention and/or water sensitivity. For these reasons, this new fluid will have widespread application in gas reservoirs and to a lesser degree will prove its value in many oil wells. The new stimulation fluid is one composed of liquefied petroleum gases and liquefied carbon dioxide in varying volumetric proportions such that the resultant liquefied gas can be used to perform hydraulic work, then allowed to perform hydraulic work, then allowed to volatilize at reservoir producing conditions.