Model Development of a Suitable Equation of State for Multicomponent Multiphase Systems: Application to Crude Oil Phase Stability Requirements

Abstract

Stability testing to determine whether or not a phase is stable is a necessary preliminary step for equilibrium calculations as well as a useful object of decision for design and management of reservoir operations. A suitable, and rodost Equation of State (EOS) model has been developed to achieve this for a reservoir fluid system over a wide range of pressure conditions. This was done by incorporating the variable parameter 'a' approach (VPAA), which treats the attractive parameter as a variable regressed by two straight lines, into the Helmholtz stability criterion. The EOS model was tested on three oil wells with high, medium and low parameter 'b' values to predict phase stability status of the fluids over a wide range of pressure conditions. For Well-1, the vapor phase was unstable while the liquid phase was stable at 47.4 atm. For Well-2, the vapor phase was stable at 209 atm. while the liquid phase was unstable For Well-3 however, the vapor phase was stable at 45.7 atm. while two liquid phases were identified. The lighter one was unstable at the temperature of interest, while the heavier one was stable at 115.9 atm

Enthalpy of Formation Modeling Using Third Order Group Contribution Technics and Calculation by DFT Method.

“…Experimental measurement is often too expensive. Predictive methods can replace measurements if they provide sufficiently good estimations [2]. The estimated properties cannot be as precise as well made measurements, but for many purposes the quality of estimated properties is sufficient.…”

Determination of limit of stability profiles for liquefied natural gas: a thermodynamic approach

“…We note here that this is true for stability analysis testing for pure compounds and binary systems but would likely, as indicated by Modell and Reid [15], become more complex with mixtures. This complexity, however, may be reduced if a major modification of the attractive force parameter of the EOS model is carried out [7,9].…”