Flow and Phase Behavior of Gas Condensate and Volatile Oils in Porous Media

Abstract

This paper was prepared for the 44th Annual California Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in San Francisco, Calif., April 4–5, 1974. 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 publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor 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 Gas and oil permeabilities were measured for gas condensate systems at high pressure levels. Similar measurements were also made for bubble point systems of different volatility at close to atmospheric pressure. Comparison made between these two systems indicates that gas condensate relative permeability values are lower in the region of low to intermediate liquid saturation than the comparable values for the bubble point systems. Furthermore, gas condensate relative permeability ratios indicate a lower critical liquid saturation than that of bubble point systems. The possibility was also investigated of retrograde liquid accumulating at the downstream end of the linear core to give liquid flow when produced under transient pressure conditions. pressure conditions. Laboratory phase behavior studies on hydrocarbon binary mixtures flowing through a porous medium were performed to test the suitability of PVT relationships obtained from steady state PVT cells in predicting condensate reservoir PVT cells in predicting condensate reservoir fluid behavior under actual flow conditions. The results obtained in this work indicate that at lower laboratory pressure depletion rates (still much greater than field rates) equilibrium is maintained during transient flow of hydrocarbon binary mixtures through porous media. At higher pressure depletion rates some nonequilibrium behavior was observed, in particular during the revaporization period. particular during the revaporization period Introduction Effective gas and oil permeabilities have been studied extensively for external gas drive and solution gas drive systems. Only limited studies have been made for retrograde reservoirs in which liquid saturation are increasing as a result of condensation from the vapor phase. Such data are required to predict the performance for condensate reservoirs and, performance for condensate reservoirs and, particularly, to interpret the behavior of wells particularly, to interpret the behavior of wells producing from these reservoirs. producing from these reservoirs. In gas condensate performance calculations conventional type relative permeability values obtained from bubble point systems with no substantial exchange of vapor liquid components are usually used if a knowledge of these values is required. However, it should be recognized that in gas condensate reservoirs, hydrocarbon liquid saturation increases from zero to a maximum value, whereas in bubble point systems relative permeabilities are usually measured in the direction of decreasing liquid saturation.