Crude Oil and Bitumen Characterization and Water-Cut Measurements for Production Surveillance

Abstract

Accurate characterization of crude oil and bitumen is critical for understanding their behavior in production, processing, and thermal recovery operations. These complex hydrocarbon systems exhibit wide-ranging molecular weights, polarities, and compositions, making direct molecular-level analysis impractical. This study presents the development and integration of advanced analytical techniques to enable rapid, accurate, and broadly applicable characterization of crude oils, bitumen, and thermal recovery products. Hydrocarbon group-type analysis via SARA fractionation, which separates crude oil into saturates, aromatics, resins, and asphaltenes based on their solubility and polarity, remains a widely used method for assessing crude oil properties. However, conventional SARA methodologies suffer from long analysis times, limited reproducibility, and reliance on petroleum-derived standards, restricting their applicability to diverse petroleum systems. To overcome these limitations, a High-Performance Liquid Chromatography-based SARA method (SARA-HPLC) was systematically improved to enable fully automated, fast, and reproducible separation of the four SARA fractions. The SARA-HPLC instrument was further standardized by introducing newly developed reference SARA materials, eliminating reliance on petroleum-derived calibration fractions, and enabling consistent application across a wide range of hydrocarbon matrices. An integrated chromatographic workflow combining gas chromatography (GC1), simulated distillation (GC2), and gel permeation chromatography (GPC) was established to provide comprehensive compositional and molecular-weight profiling across the full carbon-number spectrum (C1-C100+). The proposed workflow overcomes key limitations of traditional characterization methods while covering a full range of petroleum samples, including live crude oils and highly complex bitumen matrices. The platform was further applied to quantify solvent concentrations in actual bitumen-solvent-water emulsions produced during solvent-assisted thermal recovery. Another focus of this study is the real-time quantification of water content in produced bitumen streams under operating conditions. Therefore, a novel microwave resonator-based sensor was developed for real-time, online monitoring of water and oil concentrations in produced emulsions. The sensor provides continuous water-cut measurements, offering an actionable tool for evaluating and optimizing the performance of thermal recovery pilots.