New Oil Gelling Systems Prevent Damage in Water-Sensitive Sands

Abstract

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. This paper was prepared for the 46th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, held in New Orleans, Oct. 3–6, 1971. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal, provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Development of viscous fracturing fluids has renewed interest in fracturing with oil base materials. Oil, once the primary frac fluid, was displaced when aqueous systems allowed more flexibility and safety. Water-sensitive and some other easily damaged formations were victims of this change since most of the new developments in fracturing technology could not be applied. Recent developments have led to gelled oil systems which allow injection rates and prop carrying capacities previously unattainable with other oil base systems. These gelled oil systems can be continuously mixed to carry 10–20 sand concentrations in excess of five pounds per gallon at rates of 20 barrels per pounds per gallon at rates of 20 barrels per minute down 2-1/2 inch tubing. These systems do not damage water sensitive formations. The gel is broken by an internal breaker system. This paper describes the chemical development of the new gelling agents and their application in many experimental treatments. Rheological comparisons with other viscous frac fluids are shown and other potential applications of the systems are discussed. These include use as drilling fluids, workover fluids and packer fluids where formation damage is critical. Introduction The choice of fluids used in fracturing and their application has been cyclic in nature. Originally fracturing was done with oil exclusively. With later development of horsepower, friction control, desirability of large volume treatments, and emphasis on treatment safety, it became advantageous to use aqueous fluids, including brine, water and acid. The switch to aqueous fluids was so complete that by 1968 oil base fracturing fluids accounted for less than 10 per cent of the total volume of frac fluids pumped in the United States. pumped in the United States. With the general swing to water based fluids, research and development effort during the past 15 years has been devoted primarily to the improvement of aqueous frac fluids. Throughout this time, however, there has remained a need for oil-base fluids to treat formations which are water sensitive. Injection of aqueous fluids into these formations often fails to provide stimulation benefits and may result in a productivity decrease. Even the use of potassium chloride or calcium chloride has not been successful in fracturing many of these zones.