A Unified Model for Aggregation of Asphaltenes

Abstract

Asphaltenes are the heaviest and most polar fraction of crude oil. They can precipitate at any point of oil production or transportation as a result of changes in the temperature, pressure, or composition. Their precipitation and deposition are having a serious economic impact on petroleum production. It was previously shown that that the precipitation of asphaltenes is a kinetic phenomenon. In this work, it is demonstrated that the kinetics of precipitation is universal among many different crude oils. However, the aggregation rates strongly depend upon the properties of the crude oil or the solvent used to stabilize asphaltenes. A new method of analysis is developed to estimate the aggregation rates by accounting for the properties governing the aggregation kinetics using Smoluchowski's aggregation model. It is shown that the viscosity and solubility parameter of the solution play an important role in controlling the aggregation behavior of asphaltenes in different crude oils and different model oils. However, with certain key assumptions in the kinetic analysis, all disparities in the aggregation rates of asphaltenes for different types of asphaltenes and crude oils disappear and the rates collapse onto a single curve. These findings will lead to a better understanding of the properties that govern the destabilization and growth processes, which can, in turn, give rise to new predictive models to foresee precipitation kinetics under different operational conditions.

The bitumen microstructure: a fluorescent approach

“…The capability for self-assembly of polyaromatic structures is an often observed phenomenon. Several studies found self-ordering behavior for such molecules and it has been proven that this effect, which is caused by p-p interactions, can also be found in asphaltenes [2,12,13,19,20,55,59,62]. For most bitumina studied in literature, the natural wax fraction is below 2 wt% as measured by standard distillation methods [32], while the typical asphaltene content is around 10 wt%.…”

Impact of maltene and asphaltene fraction on mechanical behavior and microstructure of bitumen

“…The existence of ordered agglomerates has been proven by small angle X-ray scattering and small angle neutron scattering experiments [11][12][13] and the nature of asphaltene agglomeration is well established for different solvents, leading to problems and discussions regarding the size of the asphaltenes and their agglomerates [11,[14][15][16]. The existence of a bitumen microstructure and its visualization was performed by various techniques, ranging from confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) to atomic force microscopy (AFM) [17][18][19][20][21][22][23][24][25][26].…”

Agregacja, koagulacja i wytrącanie się asfaltenów ze strumieni procesowych – przegląd literatury

“…W badaniach wykorzystano asfalteny ropopochodne, a jako rozpuszczalnik: toluen, 1-metylonaftalen oraz ich mieszaninę w proporcji 1:1. Wykazano ponadto, że lepkość oraz parametr rozpuszczalności odgrywają ważną rolę w kontrolowaniu agregacji asfaltenów [20].…”