Asphaltene precipitation onsets for light and heavy oils in Argentina

JUAN MANUEL PADRÓ; CLARA SMAL; CISMONDI DUARTE, MARTIN

Congreso; PetroPhase 2021 (The 21st International Conference on Petroleum Phase Behavior and Fouling); 2021

Asphaltenes constitute the most polar and heavy fractionof crude oils, being insoluble in alkanes like n-Heptane, but soluble inToluene or other aromatics. Their precipitation from reservoir fluids oftencreates problems of different type in the oil & gas industry, includingformation damage with reduction of conductivity in the reservoir, flowassurance problems in tubing and surface facilities or flow lines, and evenfouling in refineries, due to blending of crudes of different type, which canalso cause asphaltene destabilization. In order to be able to take the rightdecisions regarding prevention and mitigation of these problems, it isimportant to know not only the asphaltene content but also -and more important-their tendency to precipitate. This can be mainly expressed through onsets,which are saturation points where precipitation starts, due to changes inpressure, temperature or composition [1].This work presents preliminary results for thedetermination of asphaltene precipitation onsets for different dead oils fromArgentina, by dilution in n-pentane or n-heptane. The experimental work wasbased on the “indirect method” as described in recent publications [2,3]. Thismethod, which is a combination of gravimetric and spectroscopy techniques, isproposed for obtaining the detection of asphaltene precipitation along thedilution process. Detection of the onset for asphaltene precipitation dependson the aging time of the samples, kind of oil, precipitating agent andtemperature. Time-dependency is related to the minimum particle size separatedby the centrifugation process. The adaptation of the default recommendations tolight or heavy oils are discussed, as well as options for pre-processing ofoils with different contents of emulsified water. To our knowledge, this is thefirst time that this type of methodology has been applied to Argentinian oils. References[1] F. M. Vargas, M. Tavakkoli, ASPHALTENE DEPOSITION:Fundamentals, Prediction, Prevention, and Remediation, CRC Press, 2018.[2] M. Tavakkoli, M. R. Grimes, X. Liu,C. K. Garcia, S. C. Correa, Q. J. Cox, F. M. Vargas, Energy Fuels, 29 (2015), 2890-2900.[3] M. Tavakkoli, A. Chen, C. Sung, K. M. Kidder, J. JinLee, S. M. Alhassan, F. M. Vargas, Energy Fuels, 30 (2016), 3676-3686.