The Coexistence of Liquid and Vapor Phases at Pressures Above 10,000 Psi

With greater effort being devoted to the discovery of new oil and gasreserves and a consequent increase in bottom hole pressures due to greaterdrilling depths, the phase relationships of hydrocarbon fluids at pressuresabove 10,000 lb psi are becoming increasingly important. The present paper discusses the results of research with a windowed cell ona methane-Kensol 16 system to pressures of 25,000 lb psi and temperatures to260'F. Kensol 16 is a commercial high narrow-boiling-range oil. It is shown that for the temperature range of 60'F to 260'F, this particularsystem exists in two phases to pressures of approximately 14,000 Ib psi, anddata are presented giving the relative amounts of liquid and vapor phasescoexisting under these conditions. Partial phase diagrams are shown for sixdifferent mixtures of methane and Kensol 16, three of which include thecritical region. In contrast to mixtures composed of substances of fairly close volatility, critical opalescence was noted for as much as ?200'F of the criticaltemperature. The critical locus of the methane-Kensol 16 system was estimated and theconventional pressure-composition and temperature-composition diagrams were prepared. From these, the equilibriumvaporization factors for methane and Kensol 16 were estimated for temperaturesfrom 60'F to 700'F and to pressures above 12,000 Ib psi. The relations of this study to petroleum production problems and other phaseequilibria research are discussed. Introduction A knowledge of the physical behavior of naturally-occurring hydrocarbonmixtures is fundamental to a thorough treatment of nearly all operationsinvolved in the recovery, refining, and transportation of petroleum. T.P. 2809