Development and investigation of a neutral-alkaline oil-displacing composition based on a deep eutectic solvent for enhancing oil recovery from heavy, high-viscosity oil pools
M. R. SHOLIDODOV, L. K. ALTUNINA
Institute of Petroleum Chemistry, Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia
Keywords: deep eutectic solvents, heavy and high-viscosity oils, oil displacement efficiency, enhanced oil recovery methods, oil-displacing composition, surfactants
Abstract
Results of the synthesis of binary systems and ternary system of deep eutectic solvents (DESs) based on glycerol, choline chloride and urea are presented, along with the studies of their physicochemical and rheological properties, including the properties of their aqueous solutions. Based on the conducted studies involving the addition of a complex surfactant to DES, a new neutral-alkaline oil-displacing composition was developed. The results of laboratory tests aimed at studying the effect of the developed composition on the filtration characteristics of the heterogeneous formation of the Usinskoye field, as well as on the composition and properties of oil itself, are presented. The neutral-alkaline oil-displacing composition is applicable to various geological and physical conditions, in particular in the northern and Arctic regions. The effectiveness of the composition was evaluated under natural, steam-thermal, and steam-cyclic development conditions. Its use was found to smooth out filtration flows, increase reservoir sweep efficiency, restore permeability, and, as a consequence, increase oil displacement efficiency significantly over a wide temperature range. Analysis of the composition and properties of heavy, high-viscosity oil using IR spectroscopy and chromatography - mass spectrometry has shown that the developed composition alters oil characteristics by breaking the bridges linking saturated hydrocarbons with the esters/acids of resinous components. This leads to an increase in the proportion of oil fractions, with a simultaneous reduction of resin content, resulting in lower viscosity and improved oil quality.
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