Advances in the application of comprehensive two-dimensional gas chromatography in petroleum geochemistry

Petroleum, a complex multi-component organic mixture, is susceptible to various physical, chemical, and biological transformations during its formation and migration. Consequently, it is difficult to identify compounds of extremely low concentrations or special compounds in petroleum using conventional one-dimensional gas chromatography (1DGC). In contrast, comprehensive two-dimensional gas chromatography (GC×GC), enjoying ultra-high resolution and sensitivity, high peak capacity, and accurate qualitative and quantitative detection results, allows for the separation and identification of complex mixtures, thus meeting the challenge of performing accurate, quantitative analyses of complex petroleum components. Key findings of this study include: (1) Coupled with various detectors such as a sulfur chemiluminescence detector (SCD), electron capture detector (ECD), flame ionization detector (FID), or a time-offlight mass spectrometer (TOFMS), the GC×GC exhibits wide application and notable efficiency in analyzing and detecting the hydrocarbon compositions and heteroatomic compounds of crude oil fractions; (2) GC×GC can be employed to analyze unresolved complex mixtures (UCMs) in heavy oil, assess the cracking degree of crude oil, determine the preservation threshold of ultra-deep liquid hydrocarbon, quantitatively assess the intensity of thermochemical sulfate reduction (TSR), and identify potential trace molecular compounds in crude oil and their structures; (3) GC×GC, which has exhibited unique advantages in the field of petroleum geochemistry, is expected to play a significant role in shale oil and gas exploration and research on the migration, accumulation, preservation, and modification of liquid crude oil in deep to ultra-deep reservoirs.