Vapor-Liquid Phase Behavior Of The Helium-Methane System

Publication Rights Reserved 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. This report presents more extensive experimental vapor-liquid equilibria data for the helium-methane system than is found in the literature. A static sampling technique was used to obtain vapor and liquid compositions for six temperatures between -180C and -85C and pressures up to 2,000 psia. Data at 2,000 psia were extended to the critical temperature of the mixture. Average scatter of the data from the smoothed lines is approximately 1 per cent of the helium concentration or 0.03 mole per cent helium, whichever is greater. Vapor compositions -140C, -160C, and -180C were analyzed by a different technique and scattered on the average from the smoothed curve less than 4 per cent of the methane concentration. Comparisons are drawn between the data of this study and the previously published work of Kharakhorin. The solubility of helium in liquid methane was found to be considerably less than the values indicated by Kharakhorin. Experimental data are presented in tabular form and in various phase-composition diagrams. The behavior of the helium-methane system is seen tb be very similar to that of the helium-nitrogen system, with helium being much less soluble in methane than in nitrogen. The data were satisfactorily correlated by means of the Krichevsky-Kazarnovsky equation. Extrapolations to higher pressures should be feasible. VAPOR-LIQUID PHASE BEHAVIOR OF THE HELIUM-METHANE SYSTEM Interest in conserving the only appreciable supply of helium has led to legislation enabling private industry to extract helium from streams of natural gases in which it occurs. The helium is purchased by the government for storage in underground formations. The separation processes used by all recovery plants now in operation depend upon low-temperature phase-equilibrium phenomena. Since helium is the least condensible of all gases, it is obtained by condensing all of the other components present in the natural gas. The helium-free natural-gas is then returned to the market stream.