American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
This paper was prepared for the Eastern Regional Meeting of the Society of Petroleum Engineers of AIME, held in Pittsburgh, Pennsylvania, November 5–6, 1970. 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 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. 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.
Silica or limestone porous materials in contact with pure hydrocarbon liquids are strongly hydrophilic. When naturally occurring surface active materials are present in the liquid, they are adsorbed at the solid surface, rendering it less hydrophilic. If the concentration of such material is sufficient, the oil-water-matrix contact angle can be significantly greater than zero. The effect of increasing temperature in such a system will usually be to shift the adsorption equilibrium causing desorption of surface active material and a decrease in contact angle.
A simple geometrical model of a porous medium is used to approximate the effect of variation in wettability, as characterized by the oil-water-matrix contact angle, on imbibition relative permeability. Based on this model and other considerations, we conclude that the following trends will occur in a series of isothermal water floods with temperature increasing;
oil-water-matrix contact angle decreases to zero;
residual oil saturation decreases;
the ratio krw/kro at a fixed water saturation can increase for materials with a low residual oil saturation such as unconsolidated sands;
the ratio krw/kro at a fixed water saturation decreases for materials with a high residual oil saturation such as consolidated sands.
Experimental observations of these conclusions are reported in the literature.
A method is presented for the correction of imbibition relative permeability curves to compensate for changes in temperature, based on the model developed.
There is considerable experimental evidence that oil-water imbition relative permeability is strongly temperature dependent. Some doubt exists however as to the nature of this dependency. Poston et al observed that at a given water Poston et al observed that at a given water saturation krw/kro increases with increasing temperature in an unconsolidated material. This same observation was made by Davidson. Poston et al also found that as temperature increases, relative permeability to water increases, residual oil saturation decreases, and the oil-water-matrix contact angle, measured in the water phase, decreases.
Habowski, using a consolidated porous medium, also found that residual oil saturation decreased with increasing temperature. He observed that in this type of material, krw/kro decreases with increasing temperature. This would appear to contradict the findings of Poston et al.