Vapor-liquid Equilibria of Natural Gas-Crude Oil Systems

Abstract

Equilibrium data are reported on the composition and densities of coexisting vapor and liquid phases as a function of pressure and temperature for four hydrocarbons systems prepared from crude oil and natural gas. The data were observed over a range of pressures from 1000 to 8220 psi and at temperatures ranging from 35 to 250oF. The compositions of the hydrocarbon systems were such that the critical temperatures of the mixtures were lower than the range of the investigation. Under these conditions, it is shown that the composition of the systems has a marked effect upon both the absolute value of the equilibrium constants and the change of the constants with pressure for the several components comprising the system. From weight-balance considerations, it has been possible to construct the partial phase diagram of a mixture of a 49.9o A.P.I. crude oil and natural gas having a gas-oil ratio of 3660 cu ft per barrel. Descriptions of the apparatus used, the analytical procedure, the material used and the equilibrium measurements are included.