Multivariate Curve Resolution Alternating Least-Squares As a Tool for Analyzing Crude Oil Extracted Asphaltene Samples

Abstract

Asphaltene deposition in the early stage of the oil reservoir life and later during any stimulation process emerges critical problems to the petroleum industry. Deposition of asphaltene aggregates raises strict problems in industries and demands markedly a practical and scientific knowledge of the mechanisms of aggregation and precipitation. Fluorescence emission spectroscopy has been widely used to illuminate the fundamental properties of crude oils and asphaltenes. It proposes analysis of some details of equilibrium, dynamic behavior, and aggregation composition of crude oil under specific condition. In this work, the fluorescence spectra of crude-oil extracted asphaltene samples were studied and analyzed by the application of multivariate curve resolution alternating least-squares (MCR-ALS). The asphaltene samples were extracted from crude oil of three different regions of Iran (Kuh-e-Mond, Bangestan, and Gachsaran). The excitation–emission fluorescence spectra of asphaltene solutions of variable concentrations (1.0–60.0 μg/mL) in toluene were recorded. The application of MCR-ALS analysis on the row-wise augmented matrices allows the identification of major components at different asphaltene solution concentration in each sample. The emission spectra, excitation spectra, and concentration profile of these components were deconvoluted to demonstrating structural features characteristic of each sample.