Abstract
Asphaltenes are known for causing flow assurance problems in numerous oil fields. In this study we present a comparative spectroscopic analysis of Xinjiang heavy oil asphaltenes as part of ongoing research for an environmentally friendly and cheap chemical inhibitor. The goal is to predict the internal morphology of these asphaltenes through comparative analysis using high precision spectroscopy. Fourier transform infrared spectroscopy (FTIR), proton-nuclear magnetic resonance (H-NMR) and electrospray ionization Fourier transform ion cyclotron resonance combined with mass spectroscopy were used in this analysis. Several studies have demonstrated the enormous potential of these techniques to characterize hydrocarbons. Here we comparatively apply these techniques to characterize Xinjiang asphaltenes with reference to earlier imaging studies with atomic force and scanning tunneling microscopy to assign a structure to these asphaltenes. Results revealed the nature of the asphaltenes to be polycyclic, aromatic with both heteroatomic and metallic content. Thirteen basic and eleven non-basic/acidic nitrogen compounds fused within the aromatic network were identified. The mass distribution is in the range between 100–800 Da. H-NMR revealed various structural parameters (aromaticity and degree of unsaturation) and together with FTIR various functional groups were identified that include: ethers, sulphides, amides and sulfoxides. The predicted structures are consistent with the “island” and “aryl linked core” models.
Highlights
Among the problems during the production of heavy oil in Eastern China is the precipitation of asphaltenes
The oil eld is a carbonate reservoir located in the northwest of china and is characterized by shallow burial and low temperatures
For analysis purposes the oil can be separated into four fractions: saturates, aromatics, resins and asphaltenes
Summary
Among the problems during the production of heavy oil in Eastern China is the precipitation of asphaltenes. Their mitigation and control is of vital importance. The oil eld is a carbonate reservoir located in the northwest of china and is characterized by shallow burial and low temperatures. The oil is categorized as heavy due to low H/C ratio and high viscosity.[2] For analysis purposes the oil can be separated into four fractions: saturates, aromatics, resins and asphaltenes. Separation/ extraction of these components simpli es oil characterization as each fraction can be independently analysed.[3,4] Saturates are aliphatic, non-polar, branched or linear including cycloalkanes
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