Evaluation of Oil Soluble Resin Mixtures as Diverting Agents for Matrix Acidizing

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 A new oil soluble resin mixture has proved extremely effective as a diverting agent for matrix acidizing treatments. The mixture has three major advantages which make it a more effective diverter than other agents currently in use:It effectively equalizes flow into zones of varying permeability.It is completely oil soluble and leaves noresidual formation damage.It can penetrate a gravel pack and divertin the formation behind the pack. It is the only diverter which is effective for this application at temperatures above 125degrees F. One of the major factors controlling the success or failure of any sandstone matrix acidizing treatment is that of proper distribution of the treating acid over the entire producing interval. Unless an effective diverting agent is used, the largest portion of the acid may be expended on only a small part of the total zone. A study was made of the various diverting agents presently used in matrix acidizing. These diverters were evaluated in terms of (1) their ability to equalize acid flow into zones of varying permeability, and (2) clean-up following the treatment without residual formation damage. Diverters evaluated included viscous gels, natural gums, emulsions, acid swellable polymers, solid organic acids and a new system employing a mixture of finely divided oil-soluble solids. Of the materials tested, some were found to be totally ineffective while others produced extensive formation damage. Best diversion was obtained with the swellable polymers or the mixture of oil soluble resins. This paper presents data comparing effectiveness of various matrix diverters. The diversion mechanism of the oil soluble resins is described and case histories are presented to show how better diversion improves production increases. Introduction In recent years, renewed interest has been shown in the use of hydrochloric-hydrofluoric acid mixtures for the matrix treatment of sandstone formations.