Application of Triazine-Based Gemini Surfactants as Viscosity Reducing Agents of Tar Sand Derived Bituminous Crude

Abstract

The bituminous crudes derived from tar sands as well as heavy crude oils are characterized by high viscosity, which poses problems during their pipeline transportation. These oils contain a significantly higher percentage of asphaltenes, which have polycondensed aromatic ring structures and tend to self-aggregate to produce a viscoelastic structure resulting in the high viscosity. Apart from blending and dilution to reduce viscosity, a method being explored is the addition of chemicals in small amounts that can hinder or alter the aggregation in such a way that the viscosity is reduced. In the present work, two novel gemini surfactants were synthesized in the laboratory by the reaction between 4-(dimethylamino) benzaldehyde and 1-bromododecane, which formed an intermediate compound in the first step. This intermediate compound was treated with 6-methyl-1,3,5-triazine-2,4-diamine to obtain the gemini surfactant N,N′-bis­{(p-(N,N,N-dodecyldimethylammonium chloride) benzylidene} 6-methyl-1,3,5-triazine-2,4-diamine, denoted as VRA-1 and separately with 6-phenyl-1,3,5-triazine-2,4-diamine to obtain N,N′-bis­{(p-(N,N,N-dodecyldimethylammonium chloride)­benzylidene} 6-phenyl-1,3,5-triazine-2,4-diamine, denoted as VRA-2. After confirming the structures of these synthesized products by elemental analysis (CHN), infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy, these were investigated for their viscosity reducing properties. Studies were carried out for their application as viscosity reducing agents (VRAs) in the bituminous crude obtained from high grade Canadian oil sands. This bituminuous crude was blended with toluene followed by doping of these surfactants in the dosage varying from 100 to 600 ppm. The rheological behavior of these was determined at temperatures of 20, 40, and 60 °C at variable shear rates. The studies indicated that these types of compounds can be effective as viscosity reducing agents for heavy crude oils. In the present case, VRA-2 has shown better performance as compared to VRA-1.

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