Thermal Recovery: Principles And Practices Of Oil Treatment
Authors: Bertness T.A. 
Published: December 2007

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This paper was to be presented at the 40th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Denver, Colorado, October 3–6, 1965, and is considered to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of the Journal of Petroleum Technology or the Executive Secretary. Such abstract elsewhere after publication in the Journal of Petroleum Technology or Society of Petroleum Engineers Journal is granted on request, providing proper credit is given that publication and the original presentation of the paper.

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.

The extensive in-situ combustion and steam operations in California have been plagued with severe emulsion problems. The severity or stability of the emulsion varies widely and is related to properties of the crude oil, producing formation, and reactions developed in thermal recovery processes. The in-situ combustion and steam injection processes create stable emulsions through addition of energy to disperse produced fluids, formation of numerous emulsifiers to stabilize the produced emulsions, and addition of fresh water to the produced fluids.

The principles and relationships of chemical treatment, heat, and treating methods, for demulsification of thermally produced crude are presented. The functions and application of treating facilities for process of heavy oil are reviewed. Stability of the emulsions must be reduced by chemical treatment in order to coalesce and separate dispersed water from crude oil within reasonable time. Appropriate selection and control of application of chemical demulsifiers to meet changing properties and rates of thermally produced crudes are necessary for successful and efficient treatment in all facilities. Data on stability of emulsions of thermally produced crude are presented.

Severe emulsion problems have been experienced in both steam injection and in-situ combustion projects in California. The purpose of this paper is to discuss the causes of the problems and the principles and practices which should be considered for successful treatment of thermally produced oil.

NATURE OF CRUDE OIL EMULSIONS

The co-production of oil and water by any recovery process may form mixtures or emulsions which are difficult to separate. Two principal requirements must be met for the oil-water mixtures to retain any degree of stability

First, energy expended in mixing oil and water must be sufficient to disperse water in oil or oil in water as minute droplets with diameters less than 25 mu. Turbulence in the flow of fluids from the bottom of the well to the treating facility usually is adequate to generate the degree of dispersion required for stability of an emulsion. The area of the interface between oil and water in a stable emulsion is substantial; for example, the interfacial area of one gallon of water dispersed as a stable emulsion would range from about 1,000 to 300,000 square feet.

Interfacial tension is measurable and independent of the size or shape of the surface. The interfacial tension or cohesive force of the interface has the tendency to reduce the interfacial area to a minimum.