Siberian Federal University

The use of new technologies will help to make an industrial transition to a highly ecological economy in the Russian Federation and produce new equipment for the use of supercritical fluids in the oil and gas industry.

Supercritical fluid (SCF) — is a state of matter in which the difference between the liquid and gas phase disappears. Simply put, it is a something between a gas and a liquid. Many organic and inorganic substances can get into such a state, reaching a certain temperature and pressure. For example, for water, the critical point is t_kr= 374.2℃ and p_kr=21.4 MPa, and for carbon dioxide — t_kr= 31℃ and p_kr=7.38 MPa.

Supercritical fluid is used for the production and processing of polymers, in the food industry, pharmaceuticals and medicine, for the production of new materials and biodiesel, for the processing of biomaterials and the regeneration of sorbents.

"Supercritical fluid in the oil and gas industry is used mainly in the petrochemical industry. For example, as a part of supercritical extraction technology, due to abilities of SCF to dissolve substances and get new ones. Such fluids are just starting to be introduced — studies are being conducted on the use of SCF for the processing and disposal of oil sludge, for hydraulic fracturing, dissolution and production of new substances from asphaltene sediments, as well as to increase oil recovery," said the co-author of the study, senior researcher at the laboratory of biofuel compositions and the laboratory of physics-chemical technologies for the development of hard-to-recover Hydrocarbon Reserves, Associate Professor of the Department of Machinery and Equipment of Oil and Gas Fields of SibFU Praskovya Pavlova.

In the oil and gas industry, carbon dioxide injection into the reservoir is widely introduced in the world to increase oil recovery. The technology has been known since the 70s. But the use and study of supercritical carbon dioxide to displace oil and increase the oil recovery coefficient is just beginning to gain momentum in the global mining industry. The ability of supercritical liquids to penetrate porous media makes them attractive for extracting hard-to-recover hydrocarbon raw materials from the subsurface.

Scientists have noted that supercritical fluids penetrate porous media more easily than liquids, in addition, they surpass gases and liquids in the ability to dissolve substances. By changing the pressure and temperature parameters, many properties of the SCF can be "adjusted". At the same time, such fluids have disadvantages — they easily dissolve rubber or polymers, which can harm existing equipment, and the process of obtaining SCF requires high pressure and temperature, which leads to energy costs. Although, for example, the water in the depths of the Earth may be in a supercritical state.

"Of the supercritical technologies in the oil and gas industry, the use of supercritical carbon dioxide is the most common. This means that you can create and implement a technology with zero carbon dioxide emissions so that it is captured and injected into the reservoir or used in the petrochemical industry. For oil corporations, this is an opportunity to become more environmentally friendly and safe for the environment, which is especially important for oil production in the conditions of the fragile ecosystem of the Russian Arctic. We need a new approach to the technique and technology of oil production, preparation and refining," said the director of the School of Engineering Physics and Radio Electronics of SibFU Andrey Minakov.

The scientist clarified that new technologies are a new niche in the market, and Russian manufacturers have every chance to become one of the first participants in the industrial transition to a "green" economy. The production of new equipment adapted to the use of supercritical fluids for the oil and gas industry can be started in the Russian Federation.

"In the USA, Canada, Mexico and Venezuela, injection of carbon dioxide into the reservoir, cyclic injection of water and gas (WAG-technology or "Huff-n-Puff process") is practiced. However, the problem of controlling the process of supercritical carbon dioxide inside oil wells is still being studied. The number of deposits with high-viscosity types of oil and bitumen is growing in Russia, and new technologies for their extraction are very much needed. In addition, they will also allow us to solve the problem of reducing greenhouse gas emissions," Andrei Minakov stressed.

The researchers reported that due to the high solvent capacity of SCF, special attention should be paid to rubber and plastic parts of oil-producing equipment (cuffs, sealing and packaging elements, etc.). Pumping and compressor pipes used for pumping carbon dioxide with water must be covered with plastic or have epoxy liners made of fiberglass. Foreign experience has shown that, if corrosion mitigation measures are followed, carbon steels can be safely used for injection of supercritical carbon dioxide.

• Learn more