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This review covers the types and applications of chemical inhibitors of gas hydrate formation in the oil and gas industry. The main directions of the development of new types of highly effective and environmentally safe “green” kinetic hydrate inhibitors (KHIs) based on biopolymers are analyzed. The structure, physicochemical properties, efficiency of gas hydrate formation inhibition, and commercial prospects of polysaccharides in preventing and controlling the formation of gas hydrates are considered. The criteria for their selection, current experimental data, and the mechanism of inhibition are presented. Recent research in the development of cost-effective, efficient, and biodegradable KHIs for industrial applications in the oil and gas industry is also presented.

In this paper, we consider natural and modified polysaccharides for use as active ingredients in scale deposition inhibitors to prevent the formation of scale in oil production equipment, heat exchange equipment, and water supply systems. Modified and functionalized polysaccharides with a strong ability to inhibit the formation of deposits of typical scale, such as carbonates and sulfates of alkaline earth elements found in technological processes, are described. This review discusses the mechanisms of the inhibition of crystallization using polysaccharides, and the various methodological aspects of evaluating their effectiveness are considered. This review also provides information on the technological application of scale deposition inhibitors based on polysaccharides. Special attention is paid to the environmental aspect of the use of polysaccharides in industry as scale deposition inhibitors.

The influence of electromagnetic field (EMF), created in the frequency range from 100 to 200 kHz, on the calcium carbonate crystallization from supersaturated aqueous solutions on the model system CaCl2 - NaHC O3 - FeSO4 at 80°C at a molar ratio of CaCl2:FeSO4 (100:1), on the steel surface and in bulk was studied. It was found out that iron ions reduce the poorly soluble scales formed total mass (mainly CaCO3) by ∼12%, both adhered to the steel surface and in the solution volume. Under the EMF influence, the adhered crystals amount on the steel surface in the Fe2+ ions presence decreases by 40% and in the absence by 14%. In volume, under the EMF influence, on the contrary, the crystals’ number increased by 15% in the iron ions’ presence, in the iron ions absence it decreased by ∼ 6%. In the Fe2+ ions presence and under the EMF influence, a decrease in the aragonite formation was noted while the calcite and vaterite content increased.

The influence of the electromagnetic field (EMF) on the corrosion of structural carbon steel in a 3% aqueous solution of sodium chloride in the presence of CO2 was studied. It is shown that the EMF increases the corrosion rate of steel by 1.13 times in a 3% aqueous solution of NaCl in the presence of CO2. When Ca2+ ions are added to the solution, the corrosion rate of steel decreases under the influence of an electromagnetic field. It is assumed that the formation of CaCO3 in the near-surface layer of the solution and its adsorption on the metal surface prevents the development of corrosion. The influence of the electromagnetic field generated in the frequency range from 100 to 200 kHz on the crystallization of CaCO3 from supersaturated aqueous solutions on the model system CaCl2 – NaHCO3 – FeSO4 is studied. It was found that Fe2+, rather than EMF, has a more significant effect on salt deposition. The efficiency of the effect of Fe2+ on the inhibition of salt deposition in the model of mineralized water CaCl2-NaHCO3 is 11.5% higher than when exposed to EMF. During the crystallization of CaCO3, the predominant formation of aragonite is observed. In the presence of iron ions and under the influence of EMF, there was a decrease in the formation of aragonite and an increase in the formation of calcite and vaterite. Keywords: electromagnetic field; corrosion; carbon steel; iron ions; scale deposition; crystallization; calcium carbonate.