IGPT experts continue looking into conversion of Domanik shale rocks

A new paper saw light in Fuel.

Scientists have found that adding nickel sulfate intensifies the in-situ conversion of kerogen-containing domanik deposits and improves the quality of the resulting synthetic oil during hydrothermal treatment.

“We achieved not only an increase in yield but also a significant reduction in the weight of synthetic oil under realistic hydrothermal processing conditions,” reports Ameen Al-Muntaser, a research associate at the Laboratory of Generation, Storage and Transportation of Hydrogen and Low-Carbon Energy Carriers.

Hydrothermal experiments demonstrated that the use of nickel sulfate increases synthetic oil yield by 6 percent when the reservoir is heated to 300 degrees Celsius, by 11.55 percent when heated to 350 degrees Celsius, and by 10.96 percent when heated to 400 degrees Celsius. Furthermore, it was found that at 350 degrees Celsius, not only does the greatest increase in synthetic oil yield occur, but its quality properties also improve significantly. Specifically, the amount of light fractions C9–C20 increases relative to heavier fractions C21–C32,” the scientist adds.

The component composition and properties of the synthetic oil were analyzed using various methods, including gas chromatography, gas chromatography-mass spectrometry, and low-field NMR relaxation.

“It was found that when the catalyst is heated to 350–400°C, it promotes the hydrogenation and degradation of heavy components (resins, asphaltenes) into lighter aliphatic and aromatic hydrocarbons. The hydrogen-to-carbon ratio increases, and the sulfur content decreases. Using X-ray phase analysis of the waste rock, the formation of a nickel sulfide active phase (NiхS6) was detected—direct evidence of hydrodesulfurization in an aqueous environment,” says Shadi Abdulrahman Said, one of the study’s co-authors.

According to the scientist, another positive effect was discovered—improved wettability of the pore space. This facilitates the injection of the catalyst along with steam and the distribution of the catalytic solution.

“A 1% nickel sulfate solution reduces the contact angle of the domanik rock from 64.85 degrees to “26.9 degrees after one minute of stabilization at 65 degrees Celsius and a pressure of 120 bar,” he explains.

The innovative nature of this approach lies in the use of an affordable, water-soluble precursor compatible with hydrothermal technologies.

The approach proposed by KFU scientists can be integrated into existing steam-thermal technologies for developing low-permeability reservoirs and oil source rocks. This will ensure higher quality synthetic oil and help reduce hydrocarbon emissions. Improving pore wettability simplifies the delivery of the catalytic agent, which contributes to efficient oil production.

The study was conducted as part of the Priority 2030 Strategic Academic Leadership Program for the project “Supercritical Fluid Technologies for Improving Oil Production Efficiency in Low-Permeability Reservoirs and Oil Source Rocks.”