Asphaltenes flocculation mechanism based on population balance modeling

Author of the article:CHENG Liang1, YUAN Yongwen1, ZHU Xiuyu1, DU Yin2, HE Weirong1, JIA Bixia1, LIU Xinliang3, WANG Ming4

Author's Workplace：1. Drilling and Production Technology Research Institute, PetroChina Qinghai Oilfield Company, Dunhuang, Gansu, 736202, China; 2. No.2 Oil Extraction Factory, PetroChina Qinghai Oilfield Company, Dunhuang, Gansu, 736202, China; 3. Advanced Chemical Engineering and Energy Materials Research Center, China University of Petroleum (East China), Qingdao, Shandong, 266580, China; 4. State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao, Shandong, 266580, China

Key Words：Asphaltene; Flocculation; Population balance modeling

Abstract：The flocculation of petroleum asphaltenes poses significant challenges in the production, processing, and transportation of petroleum products. However, the asphaltene composition varies widely in different production sites and storage conditions, and the mechanism behind the flocculation is not well understood. This makes it difficult to select the appropriate asphaltene deposition inhibitor according to the field conditions. To gain a better understanding of the flocculation mechanism of petroleum asphaltenes, we conducted experimental research on the dynamic process of asphaltene flocculation and developed a population balance modeling for numerical simulation, aiming to regulate the size, structure, and strength of asphaltene flocs and predict their behavior in the flocculation system. The effect of asphaltene concentration, the volume ratio between toluene and n-heptane solvents, and the shear rate on the flocculation were studied. At the same time, the floc structure was introduced into the population equilibrium model to simulate the flocculation process. The experimental results show that the flocculation process of asphaltene particles is mainly affected by the shear rate; and the population balance model, which considers changes in floc structure, provides more accurate results. With the population equilibrium model, we are able to effectively simulate the evolution of flocs particle size over time during the asphaltene flocculation process. The results of this research will contribute valuable strategies to address the challenges posed by asphaltene flocculation in oil production, transportation, and refining processes.