Predicting the asphaltene stability in crude oils from different production streams is very useful in the petroleum industry because it allows avoiding serious problems caused by formation of solid deposits during oil flow. That prediction can be carried out by applying the solubility parameter (δ) of each oil, as calculated by the asphaltene precipitation onset value, obtained by titration with n-heptane. However, many crude oils do not have a well-defined precipitation onset point, which can be overcome by adding a crude oil assumed as the standard. This article analyzes the influence of a crude oil (called APS) on the precipitation onset of two other petroleum samples (called APA and APB). For this purpose, the asphaltene fractions C3I and C5I were extracted from APS, and the influence of the addition of this crude oil as well as its asphaltenes fractions in samples of oils APA and APB was evaluated by tests involving titration of n-heptane with detection by near-infrared spectroscopy (NIR). The calculation of the solubility parameters of the oils without well-defined precipitation onset, by adding the oil with well-defined precipitation onset, led to varied errors in function of the type of oil in question. The smallest errors were obtained when using, as the solubility parameter of the mixture (δ_M), the solubility parameter of the solvent system at the precipitation onset of the asphaltene C3I fraction (extracted from the crude oil assumed as the standard) in toluene, determined by titration with n-heptane.

中文翻译：

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沥青沉淀开始：添加第二种原油或其沥青馏分（C3I和C5I）的影响

预测来自不同生产流的原油中沥青质的稳定性在石油工业中非常有用，因为它可以避免因油流期间形成固体沉积物而引起的严重问题。可以通过应用每种油的溶解度参数（δ）进行预测，该溶解度参数由沥青质沉淀起始值计算得出，沥青质沉淀起始值是通过用n滴定而获得的。-庚烷。但是，许多原油没有明确定义的沉淀起始点，可以通过添加假定为标准的原油来克服。本文分析了原油（称为APS）对其他两种石油样品（称为APA和APB）沉淀开始的影响。为此，从APS中提取了沥青质馏分C3I和C5I，并通过涉及n滴定的试验评估了该原油及其在沥青APA和APB样品中的沥青质馏分的影响。-庚烷，可通过近红外光谱（NIR）检测。通过添加具有明确的沉淀开始的油来计算没有明确的沉淀开始的油的溶解度参数，导致所讨论的油的类型的函数出现各种误差。使用时，获得最小的误差，作为混合物（δ的溶解度参数_中号）所示，在沥青质C3I馏分的析出开始的溶剂体系的溶解度参数（从原油中提取假定为标准）在甲苯中，通过用正庚烷滴定确定。