Abstract Asphaltenes insolubility is recognized as an important flow assurance problem during crude oil production. In this work, phase behavior for crude oil + methane and crude oil + methane + carbon dioxide mixtures were studied for two Brazilian pre-salt crude oil samples, with low asphaltenic content. From PVT compressibility experimental data, phase equilibria were studied based on solubility parameter, cohesive energy, and internal pressure approach. For the crude oil + methane systems, methane content was evaluated from 25.0 to 75.0 mol%, at a temperature range from 313.15 to 373.15 K. No asphaltene precipitation was observed and a minimal solubility parameter was reached at the richest methane content. Additionally, a marked reduction of cohesive energy was observed increasing methane content, probably associated to the system asymmetry. For the crude oil + methane + CO2 systems, a constant gas composition of 75.0 mol% was studied. Carbon dioxide (CO2) content varied from 0.0 to 100.0 mol%, balanced with methane, for a temperature domain of 343.15 to 383.15 K. For these systems, asphaltene insolubility regions were detected. Moreover, the addition of CO2 contributed to asphaltene stabilization. Solubility parameter and internal energy increases were properly identified for these mixtures and it could be associated to the asphaltene region reduction.

中文翻译：

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原油 + 甲烷 [T = 311.15–373.15 K] 和原油 + 甲烷 + CO2 混合物 [T = 343.15–383.15 K] 的实验相行为和溶解度参数

摘要 沥青质不溶性被认为是原油生产过程中一个重要的流动保障问题。在这项工作中，研究了两种沥青质含量低的巴西盐下原油样品的原油 + 甲烷和原油 + 甲烷 + 二氧化碳混合物的相行为。从 PVT 可压缩性实验数据，基于溶解度参数、内聚能和内压方法研究相平衡。对于原油 + 甲烷系统，在 313.15 至 373.15 K 的温度范围内，评估的甲烷含量为 25.0 至 75.0 mol%。没有观察到沥青质沉淀，并且在甲烷含量最高时达到了最小溶解度参数。此外，观察到内聚能显着降低，甲烷含量增加，这可能与系统不对称有关。对于原油 + 甲烷 + CO2 系统，研究了 75.0 mol% 的恒定气体组成。二氧化碳 (CO2) 含量从 0.0 到 100.0 mol% 不等，与甲烷平衡，温度域为 343.15 到 383.15 K。对于这些系统，检测到沥青质不溶性区域。此外，二氧化碳的加入有助于沥青质的稳定。这些混合物的溶解度参数和内能增加被正确识别，并且可能与沥青质区域减少有关。CO2 的加入有助于沥青质的稳定。这些混合物的溶解度参数和内能增加被正确识别，并且可能与沥青质区域减少有关。CO2 的加入有助于沥青质的稳定。这些混合物的溶解度参数和内能增加被正确识别，并且可能与沥青质区域减少有关。