基于相稳定性分析的油气相包络线计算新方法OA

Stable and reliable calculation of phase envelopes for hydrocarbon systems is a key and challenging aspect of reser-voir fluid phase behavior research.The saturation pressure curve tracing algorithm proposed by Michelsen represents a milestone contribution in this field and is still widely used today.However,this method involves complex technical details,making it difficult to implement correctly,and is prone to non-convergence issues during computation,which may prevent the generation of a complete phase diagram.This paper presents a novel method for accurately constructing phase diagrams of oil and gas hydrocarbon systems based on phase stability analysis combined with the bisection method.In this approach,phase stability analysis is first used to compute the cricondenbar and the cricondentherm on the phase envelope.Based on these two points,the pressure-temperature plane is divided into four regions.Within each region,the phase boundary is located using a combination of phase stability analysis and the bisection method,ultimately leading to the construction of a complete phase diagram.The pro-posed method is applied to compute phase diagrams of various reservoir fluids,and the results are compared with those obtained using Michelsen's method.The comparison demonstrates that the proposed algorithm is capable of calculating phase diagrams of oil and gas hydrocarbon systems reliably and stably.