Fluid characterization plays a prominent role in identifying the properties of the crude oil, particularly the equilibrium conditions. It gains more importance, especially in problematic crudes that, for instance, contain precipitating constituents, like Asphaltene. Aside from the pressure depletion, enhanced Asphaltene precipitation during the miscible gas injection causes many problems to the production system. Therefore, the employed characterization procedure must be able to predict the Asphaltene instability conditions effectively. Recently a class of solution techniques using the perturbed chain statistical associating fluid theory (PC-SAFT) and dealing with Asphaltene phase as a liquid-like phase have gained attractions in literature. However, such techniques could not consider the effect of the injected gas composition and structure, because they lumped all the heavy gas components in a single pseudo-component. Hence, in this study, a detailed characterization method is proposed that can account for the heavier gas components. The modeling approach in this work, assumes the liquid-like Asphaltene framework and PC-SAFT for phase behavior calculations. In this work, the three PC-SAFT parameters for Asphaltene and Aromatic + Resin are simultaneously regressed with gas injection, to match the saturation and Asphaltene onset pressures with experimental data. The outcomes of this study are compared with the experimental data and previous characterization models. The results prove the ability of the detailed characterization approach for predicting the bubble point and Asphaltene onset pressures. It not only leads to lower estimation errors in most cases but also can capture the actual trend of bubble and Asphaltene onset curves, which makes it even more reliable for the prediction of instability conditions.

流体表征在识别原油特性（尤其是平衡条件）方面起着重要作用。它变得尤为重要，尤其是在有问题的原油中，例如含有沉淀成分的沥青质。除了压力消耗外，在混溶性气体注入过程中沥青质沉淀的增加也给生产系统带来许多问题。因此，采用的表征程序必须能够有效预测沥青质的不稳定性条件。最近，一类使用扰动链统计缔合流体理论（PC-SAFT）并将沥青质相作为液态相处理的解决方法在文献中引起了人们的注意。但是，此类技术无法考虑注入的气体成分和结构的影响，因为它们将所有重气组分都集中在一个假组分中。因此，在这项研究中，提出了一种详细的表征方法，可以解释较重的气体成分。在这项工作中，建模方法假设使用液体状沥青骨架和PC-SAFT进行相行为计算。在这项工作中，沥青质和芳族树脂的三个PC-SAFT参数与气体注入同时回归，以使饱和压力和沥青质起始压力与实验数据相匹配。这项研究的结果与实验数据和以前的表征模型进行了比较。结果证明了详细表征方法能够预测起泡点和沥青质起始压力。