The Microscopic Mechanism of Asphaltene Deposition and Prevention of Deposition During Oil Extraction

The problems caused by asphaltene deposition, such as wellbore blockage, pump jamming, and spot corrosion, directly affect the development and exploitation of oil fields, which may increase the difficulty and cost of oil extraction operations. It is one of the important problems that urgently need to be solved in the oil extraction process. Herein, based on the real oil well blockage samples, the composition and properties of crude oil was analyzed, and the molecular structures of crude oil saturates, aromatics, resins and asphaltenes were designed. The mechanism of each component deposition to form blockage was researched from the molecular scale, and the microscopic mechanism of dispersant stabilizers in preventing deposition was explored. The results indicated that the adsorption energy order of the four fractions of crude oil on the simulated pipe wall was: asphaltene > aromatic > saturate > resin. Compared with other molecules, asphaltene had the lowest binding energy at the interface and was most easily adsorbed at the interface. Driven by the structure of heteroatoms and multi-aromatic rings, most asphaltene molecules accumulated at the interface in a “lying flat” form. The centroid distance between the simulated crude oil molecules and the simulated pipe wall significantly increased after adding dispersant stabilizers, effectively preventing the adsorption and deposition of asphaltene and aromatic. The mechanism of the deposition of the four fractions in crude oil to form blockages was explored, which would provide a theoretical basis for further research on the removal of asphaltene deposition and new ideas for the design of efficient dispersion stabilizers.