Peeling Off Mechanism Of Asphaltene In The Presence Of Amphiphilic Polyelectrolytes

As accessible conventional crude oil declining and the demand of crude oil increasing,the development of technology to exploit unconventional oil,such as heavy oil,is urgently needed.However,heavy oil with a high content of asphaltene possessing high viscosity was illiquid,which has brought many difficulties to heavy oil exploitation.So,the desorption of asphaltene on heavy oil reservoir,the peeling off phenomena in pipeline as well as the corresponding microscopic mechanism,has important scientific significance.Asphaltenes were extracted from the oil sand in Long Lake of Canada in this study,and its composition and content have been characterized by XPS photoelectron spectroscopy,element analysis.It suggested that asphaltenes were adsorbed to the silica surface through the polar interaction,until it reaches saturation.The dynamic mechanism of asphaltenes desorbed from silica surface in the presense of amphiphilic macromolecules was investigated in situ by QCM-D.The asphaltenes were desorbed through electrostatic and polar interactions between polymers and asphaltenes,as well as the electrostatic interactions between polymers and binding sites of the solid surface.With an increase of concentration,hydrophobic domains were formed by intermolecular hydrophobic effect,which can remove the asphaltenes from silica surface by entrapment.Combined with the results of UV-vis spectroscopy and atomic force microscopy respectively,the actual asphaltene content in effluent and the adsorption layer morphology has been characterized,which further demonstrated the microscopic competitive adsorption mechanism between asphaltenes and polymers from silica surface.Finally,based on the Random sequence Model(Random Sequential Model,RSA)and take the diffusion effect as well as the concentration change of asphaltene and polyelectrolyte molecules in the competitive adsorption process into consideration,a new adsorption Model was established,which make an insight into asphaltene microscopic stripping mechanism by polymer.