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

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.