Interfacial Tensions at Reservoir Pressures and Temperatures; Apparatus and the Water-Methane System

Abstract

Abstract An apparatus for the determination of fluid-fluid interfacial tension by thependant drop method has been constructed. The apparatus is refined beyond thosepreviously described in that the samples are introduced into an evacuatedwindowed cell without contacting air or mercury. Interfacial tension data are reported for the water-methane system between 74and 280'F and 15 and 15,000 psi. The variation of wettability of the stainless-steel dropper tip withpressure and temperature was observed incidentally to the measurements. Introduction The most refined previous apparatus for the determination of fluid-fluidinterfacial tension at reservoir conditions was built by Hauser and Michaels.These authors used the pendant drop method, previously investigated by Andreas, Hauser, and Tucker. Recently, Fordham has made the pendant drop method anabsolute one by numerical integration of the differential equation of dropshape. It is necessary to know the difference in density of the two fluids andthe acceleration due to gravity in order to evaluate the interfacial tensionfrom measurements of drop dimensions. Contact angle is not involved in themeasurements by this method. Some precise tests of the method have been made at atmospheric pressure and77?F by Douglas, who found agreement with established values to within about0.1 per cent for water and air, cyclohexane and air, benzene and air, andbenzene and water. No values of interfacial tension from the recent pendantdrop apparatus have been published by Hauser and Michaels. However, values forthe water-benzene and water-decane systems are given in Michaels thesis forpressures from 15 to 10,000 psi and temperatures from 73 to 268?F. Somedeterminations on gas-oil and gas-water systems in the range of 15 to 4,000 psiand 78 to 178 of have been made by Hocott, by the drop-volume method. Thecapillary rise method has been used to investigate the interfacial tension ingas-oil systems at 88 of to several thousand psi by Swartz. Otherdeterminations in gas-oil systems at pressures under 1,000 psia have been madeby Jones, and Beecher and Parkhurst. The scarcity of data for pressures above5,000 psi is apparent. T.P 3019