In this study a new, fast and simple method based on low field NMR-relaxometry for in-situ determination of SARA (saturates, aromatics, resins and asphaltenes) composition of crude oils was proposed. This method was tested on 22 samples of crude oils with a wide range of SARA-composition and API gravity values (4.6–42.0°), including extra-heavy, heavy, medium and light crude oils. Results obtained by low-field nuclear magnetic resonance (LF-NMR) were compared with conventional SARA analysis method (ASTM D 4124). Comparison shows good coincidence between SARA values determined by LF-NMR and conventional method data for heavy fractions of asphaltenes and resins (R² is equal to 0.98 and 0.90, respectively) and for the sum of light fractions including saturates and aromatics (R² = 0.96). However, comparison for saturated and aromatic compounds separately gave low correlation coefficients (R² ≤ 0.64 and 0.34, respectively) and relatively soaring standard deviation for individual correlations for saturates and aromatics (8.42 and 9.27). Consequently, LF- NMR relaxation as an alternative method for studying the composition of crude oil allows the determination of asphaltenes, resins and the sum of light fractions (saturates and aromatics) without their extraction (in-situ), which greatly simplifies and accelerates conventional chromatographic analysis. This method can be successfully applied for different types of crude oils with a wide range of API gravity and viscosity values.

在这项研究中，提出了一种新的，快速，简单的基于低场NMR松弛法的原位测定原油中SARA（饱和，芳香族，树脂和沥青质）组成的方法。该方法在22种具有广泛SARA组成和API重力值（4.6–42.0°）的原油样品上进行了测试，其中包括超重，重，中和轻度原油。通过低场核磁共振（LF-NMR）获得的结果与常规SARA分析方法（ASTM D 4124）进行了比较。比较结果表明，通过LF-NMR测定的SARA值与常规方法数据中的沥青质和树脂的重质馏分（R ²分别等于0.98和0.90）以及轻质馏分的总和（包括饱和烃和芳烃（R ²））具有良好的一致性。 = 0.96）。然而，对于饱和及芳族化合物相比，分别得到低相关系数（R ² 分别≤0.64和0.34）和相对飞涨标准偏差为饱和物和芳烃（8.42和9.27）个体的相关性。因此，LF-NMR弛豫作为研究原油组成的另一种方法，可以测定沥青质，树脂和轻馏分（饱和烃和芳烃）的总和，而无需原位萃取，这极大地简化了传统方法并加速了常规方法的应用。色谱分析。该方法可以成功地应用于具有多种API重力和粘度值的不同类型的原油。