(580b) Effects of Precipitant Concentration On Asphaltene Deposition

Asphaltene deposition is a costly concern in flow assurance. Precipitation and deposition can occur in the porous rock formations, well-bore, production lines and in the refinery. Capillary deposition has been considered a useful tool to measure the conditions under which deposition occurs and the extent of deposition. Previous research has studied the effect of different precipitants, deposition near onset and past onset conditions, and the effect of shear rate [1,2]. Recently, it has been shown that a critical onset point is not sufficient and there are kinetic effects associated with the precipitation and aggregation of asphaltenes [3]. Both the time required to detect precipitated asphaltenes and the quantity of asphaltenes precipitated is a strong function of the precipitant concentration. Previous deposition work has not considered the effects of precipitation kinetics.

This investigation examines the effect of precipitant concentration, as a parameter to control the precipitation kinetics, on the deposition characteristics of asphaltenes in crude oil. Key measured deposition characteristics include rate of deposition, thickness of deposit and deposit location. In addition to varying the volume fraction of precipitant, temperature effects and types of precipitant are also considered. Previous work has considered the formed deposit to be uniform distributed over the entire length of the capillary; the validity of this approach is also under investigation. The primary goal is to develop a fundamental understanding of the deposition process and how aggregation effects can be incorporated into a model of the capillary deposition process.

[1] J. Wang, J.S. Buckley, and J.L. Creek, ?Asphaltene Deposition on Metallic Surfaces,? Journal of Dispersion Science and Technology, vol. 25, 2004, pp. 1-12.

[2] L. Nabzar and M.E. Aguilera, ?The Colloidal Approach. A Promising Route for Asphaltene Deposition Modelling,? Oil and Gas Science and Technology Revue De Linstitut Francias Du Petrole, vol. 63, 2008, pp. 21-35.

[3] T. Maqbool, et al, ?Kinetics of Asphaltene Precipitation from Crude Oils,? The 9th International Conference on Petroleum Phase Behavior and Fouling, Victoria, Canada: 2008.