The Roles of Magnetic Field & Oil Composition in Treatment of Heavy Organics in Petroleum Fluids
thesisposted on 01.08.2019, 00:00 authored by Mohammed Hamza Khalaf
Asphaltenes are known to have a high tendency to form aggregates that may eventually deposit causing fouling in porous media of the oil reservoirs and flow lines. Literature is rich with the statistical and macroscopic aspects of asphaltene aggregation and deposition but there is a lack of understanding the fundamentals of asphaltenes and their behavior at microscopic level. A series of molecular dynamics simulations were performed to investigate the phenomenon of asphaltene aggregation and deposition and the aggregation inhibition techniques such as applying an external magnetic field. The results showed that asphaltene behavior was affected by the aromaticity of the associated organic solvent and the molecular structure of asphaltene fragments. However, the key determinant of asphaltene aggregation is the molecular structure of asphaltenes whereas the number and length of chains, the presence of heteroatoms, and the number and size of the aromatic cores influence the aggregation intensity. In addition to the asphaltene structure, the injected gases (nitrogen and air) enhanced the asphaltene aggregation significantly, whereas structures with long aliphatic chains and archipelago architecture revealed low association affinity than other flat asphaltenes. To alleviate asphaltene aggregation, an external magnetic field with different intensities was applied on asphaltene aggregates and the governed results showed an increase and decrease in asphaltene aggregation depending on magnetic field intensity, the medium, and asphaltene structure. Finally, the aggregated asphaltenes showed a tendency to be deposited on calcite surface (both rough and smooth). Deposition kinetics are influenced by the calcite surface morphology such that the deposition was higher on the rough surface than on the smooth surface. These results provide microscale insights on asphaltene aggregation, deposition and aggregation inhibition under different conditions which contribute positively in improving the application of enhanced oil recovery.