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A MoO 3 /deep eutectic solvent (DES) catalyst precursor solution was prepared by dissolving molybdenum trioxide in a DES based on choline chloride/urea. The catalyst precursor solution was characterized for its physical and chemical properties. The characterization results showed almost no change in the DES properties after the addition of MoO 3 . The solution was used in the catalytic upgrading reaction of heavy crude oil. The performance of the catalyst was analyzed by gas chromatography−mass spectrometry, Fourier transform infrared, and viscosity measurements of the heavy oil before and after the reaction. The use of the catalyst in the catalytic aquathermolysis showed an increase in the oil viscosity. In the presence of hydrogen and catalyst, the results showed a 43% reduction in the heavy oil viscosity, a 2.5°increase in the API gravity, and 32 wt % sulfur reduction.

Summary Because of increasing energy demand, unconventional resources such as heavy oil are being explored and recovered. Enhanced-oil-recovery (EOR) methods such as surfactants and polymer flooding must be optimized and new chemicals must be designed to produce more oil. This paper introduces a new deep eutectic solvent (DES) that is based on choline chloride/ethylene glycol for EOR. As preliminary investigations revealed, different concentrations of DES solutions in brine (0 to 100 vol%) were characterized by measuring density, viscosity, conductivity, surface tension, and refractive index at different temperatures (25 to 55°C). Then, the effects of the DES/brine solutions on emulsification with oil phase, wettability alteration, oil/solvent interfacial tension (IFT), formation damage, and tertiary heavy-oil recovery were studied. Potential of the DES solution on enhancing heavy-oil recovery was explored by use of coreflood experiments. This was performed at reservoir condition (pressure = 1,200 psi, temperature = 45 to 80°C) with Berea sandstone core samples and fluids from the field of interest (formation brine and crude oil). An increase in IFT rather than a decrease was observed between the DES/brine solution and the oil. The spontaneous-water-imbibition tests suggested that a decrease in oil-wetness led to an increase in oil production. Approximately 52% of residual oil after waterflooding was recovered with the DES from the coreflooding. The results show an increase in oil recovery with reservoir temperature (6, 13, and 16% on the basis of initial oil in place at 45, 60 and 80°C, respectively). The interaction of the DES with the core materials did not lead to formation damage, as demonstrated by the permeability measurements of the DES/brine solution before and after injection. Viscous forces and wettability alteration were found to be the dominant mechanisms for the tertiary oil-recovery enhancement.

Steam injection has become commercially available thermal enhanced oil recovery methods for recovering heavy crudes. Recently, there has been increase in research interest in in-situ catalytic upgrading. In this work, experimental investigations on the application of a new submicron dispersed trimetallic catalyst based on Ni-Co-Mo for enhanced recovery and upgrading of Omani heavy crude oil was conducted. The catalysis effect of the ultra-dispersed Ni-Co-Mo metals generated in-situ from water-in-oil emulsion was studied in the presence of sand packed bed as a porous medium in a steam simulation process. The results from the recovery tests showed a higher oil recovery (15% OOIP) in the presence of the catalyst than base steam injection case. Substantial improvement in quality of produced oil was observed as there was a tremendous reduction in oil's viscosity of about 25% with significant reduction in sulfur (26%), and increase in API gravity (10%). This enhancement of the quality of Produced liquids in terms of increase in API gravity, viscosity and sulfur reduction, is an indication of successful in situ upgrading of the oil. Analysis of solid and gaseous products recovered from the experimental runs conducted with the catalyst showed thermal expansion and viscosity reduction due to catalytic hydrocracking as the dominant mechanisms for oil recovery.