Effect of Ultrasonic Irradiation on Coalescense and Separation of Crude Oil-Water Emulsions

Abstract

This paper was prepared for the 41st Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Dallas, Tex., Oct. 2–5, 1966. 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 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. 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 The coalescing and separating tendencies of untreated and treated crude oil-water emulsions when exposed to ultrasonic treatment are experimentally investigated. Combined ultrasonic and chemical treatment greatly increased separation efficiency over chemical treatment exposed only to low-frequency mechanical agitation. Both short- and long-duration ultrasonic irradiations were effective in producing coagulation: the rate of separation increased as much as 700-fold over natural settling rates. The ultrasonic treatment technique offers a potentially practical method of improving natural oil-water coalescence and separation while simultaneously decreasing chemical requirements. Introduction One of the recurring problems which has bontinually plagued the oil industry is separation of water produced with oil. The significance of this problem is shown by an estimated 15 to 20 million dollars expended for chemicals each year to treat the world's oil production. This expense does not include costs for handling the demulsifier, injection equipment, heater fuel, etc. Current methods of treating oil-water emulsions utilize natural settling, chemical dehydration, and/or electrical dehydration techniques to effect separation. Sonic energy may be used to cause either agglomeration or dispersion of immiscible liquids, depending upon frequency, wave energy, geometry, etc. A detailed literature survey revealed that, while a considerable amount of work has been done on sonic vibration as a coagulating force in aerosols and dust-gas systems, relatively little has been published on the use of this same force in separation of immiscible liquid systems. It is the purpose of this paper to present the results of an experimental investigation showing the capability of ultrasonic treatment to increase the rate of coalescence and settling of naturally occurring crude oil-water emulsions and increase the rate of dispersion of chemical demulsifying agents.