Performance Analysis of Compositional and Modified Black-Oil Models For a Gas Lift Process

Artificial gas lift is frequently used to boost production rate of mature oil fields. An integrated mathematical model was developed in order to track the spatial and temporal changes in various components of the continuous gas lift process. The computational demand for solving the comprehensive gas lit model highly depends on the thermodynamic treatment of the hydrocarbon fluids involved. A full compositional treatment using an equation of state provides the most accurate results but at a high computational cost. The results of this article showed that the computational cost can be halved without sacrificing accuracy by using reduced parameter stability and flash calculation procedures. It was also demonstrated that a Modified Black-Oil treatment of the fluids can provide reasonable accuracy at a much-reduced computational cost. The Modified Black-Oil treatment provides a valuable tool when the model has to be solved many hundreds of times to find the optimal combination of the gas lift parameters.