Asphaltene precipitation is one of the major flow-assurance problems in petroleum engineering. Asphaltene precipitation in the reservoirs can lead to formation damage, while asphaltene precipitation in the production tubing can reduce the production rate and even plug the production tubing. It may occur to the naturally produced oil experiencing pressure/temperature changes or during gas injection processes (e.g., CO₂ flooding) for enhanced oil recovery. It is a prerequisite to accurately predicting under what conditions asphaltene precipitation will occur and how much precipitates if it occurs in order to better predict and control flow assurance problems due to asphaltene precipitation. In this work, a robust three-phase vapor-liquid-asphaltene precipitation algorithm is developed. To make the algorithm more robust and effective, the new algorithm is built based upon two previously proven works: the asphaltene precipitation model proposed by Kohse et al. (1993) which considers the effects of pressure, temperature and gas injection on asphaltene precipitation, and the initialization method and algorithm developed by Li and Li (2019) which does not consider the effect of temperature on asphaltene precipitation. The algorithm is validated using the asphaltene precipitation data measured by Jamaluddin et al. (2000 and 2002) and Gonzalez et al. (2004). As for the first two oil samples (Jamaluddin et al., 2000 and 2002), both the onset conditions and the amounts of asphaltene precipitation are computed with the consideration of varied pressure-temperature conditions and the injection of different gases. The pressure-temperature (PT) phase diagrams and the pressure-composition (Px) phase diagrams are drawn to illustrate the calculation results. Our algorithm is shown to be converged at every test point involved in the three-phase equilibrium calculations for constructing the PT and Px phase diagrams. After being calibrated using the measured asphaltene onset data for the second and third oil samples, the three-phase VLS equilibrium calculation algorithm is shown to be capable of making reliable predictions of the PT phase diagrams with gas injection and the precipitated asphaltene amounts versus injectant concentration.

沥青质沉淀是石油工程中主要的流量保证问题之一。储层中的沥青质沉淀会导致地层破坏，而生产油管中的沥青质沉淀会降低生产率，甚至堵塞生产管。天然产生的油可能经历压力/温度变化或在注气过程中发生（例如，CO ₂驱）以提高采油率。准确预测在什么条件下会发生沥青质沉淀，以及发生多少沉淀，这是前提条件，以便更好地预测和控制由于沥青质沉淀引起的流量保证问题。在这项工作中，开发了鲁棒的三相汽-液-沥青沉淀算法。为了使该算法更健壮和有效，该新算法是基于两个先前已证明的工作构建的：Kohse等人提出的沥青质降水模型。（1993）考虑了压力，温度和气体注入对沥青质沉淀的影响，以及Li和Li（2019）开发的初始化方法和算法没有考虑温度对沥青质沉淀的影响。该算法使用Jamaluddin等人测量的沥青质降水数据进行了验证。（2000年和2002年）和Gonzalez等人。（2004）。对于前两个油样（Jamaluddin等人，2000和2002），考虑到不同的压力温度条件和注入不同的气体来计算起始条件和沥青质沉淀量。压力-温度（PT）相图和压力组成（绘制Px相图以说明计算结果。我们的算法显示可以收敛到三相平衡计算中涉及的每个测试点，以构造PT和Px相图。在使用测得的第二个和第三个油样的沥青质起始数据进行校准后，三相VLS平衡计算算法被证明能够对气体注入和沉淀的沥青质相对于注入剂浓度的PT相图做出可靠的预测。