Abstract:

Precipitation of organic solid, such as wax, resin and asphaltene is a common phenomenon in many production locations and it severely affects the production process. In this paper, a thermodynamic model of gas-liquid-solid phase equilibration is proposed on the basis of the equation of state and solution theory. The non-ideality of the solid phase is modified with the regular solution theory, and the phase behavior of both gas and liquid phases is described with the equation of state. A simulating calculation for an oil-gas system is conducted. The result shows that pressure has a marked effect on the precipitation temperature of wax, and this effect is even greater when below saturation pressure than above saturation pressure.

Key words: oil-gas system, wax precipitation, temperature, pressure, phase equilibrium, thermodynamic model