ACID COMPOSITION BASED ON DEEP EUTECTIC SOLVENTS FOR DISPLACING HEAVY OIL

A composition characterised by adjustable physicochemical parameters within a broad range has been developed relying on the results of studies of the phase equilibria in the ternary system of deep eutectic solvents (DES) glycerol - carbamide - boric acid. The effect of this composition on oil recovery enhancement is studied, and results obtained in the laboratory studies of the effect of DES-based composition on the filtration characteristics of a heterogeneous formation in the carbonate reservoir of the Usinsk field are presented. The efficiency of the composition for oilfields at the early and late stages of development has been assessed by physical modelling. The treatment of a model of a heterogeneous reservoir with the composition is determined to cause a substantial increase in oil displacement coefficient at either low or high temperatures due to equalisation of filtration flows, an increase in reservoir coverage, and restoration of initial permeability. Investigation of the composition and properties of heavy high-viscosity oil before and after treatment with the composition shows that the application of DES-based acid composition does not affect the qualitative composition of oil. The use of the composition leads mainly to redistribution of the content of low- and high-molecular structures: predominantly light occluded hydrocarbons are displaced, while heavy oil components are adsorbed on the reservoir.