The unique properties of supercritical fluid technology have found wide application in various industry sectors. Supercritical fluids allow for the obtainment of new types of products with special characteristics, or development and design of technological processes that are cost-effective and friendly to the environment. One of the promising areas where supercritical fluids, especially carbon dioxide, can be used is the oil industry. In this regard, the present review article summarizes the results of theoretical and experimental studies of the use of supercritical fluids in the oil and gas industry for supercritical extraction in the course of oil refining, increasing oil recovery in the production of heavy oil, hydraulic fracturing, as well as processing and disposal of oil sludge and asphaltenes. At the end of the present review, the issue of the impact of supercritical fluid on the corrosion of oil and gas equipment is considered. It is found that supercritical fluid technologies are very promising for the oil industry, but supercritical fluids also have disadvantages, such as expansion or incompatibility with materials (for example, rubber).

One of the most effective technologies for recycling organic waste is its thermal destruction by pyrolysis methods to produce valuable products such as hydrogen and mixtures containing hydrogen. Increasing the thermal power of the flow helps to reduce the formation of secondary reactions, making the non-condensable hydrocarbon gas in the pyrolysis process cleaner, which simplifies further technology for the production of hydrogen and hydrogen-containing mixtures. In addition, the economic viability of pyrolysis depends on the energy costs required to decompose the organic feedstock. Using passive intensifiers in the form of discrete rough surfaces in heat exchanging channels is a widely used method of increasing heat transfer. This paper presents the results of numerical and experimental studies of heat transfer and hydraulic resistance in a channel with and without hemispherical protrusions applied to the heat transfer surface. The investigations were carried out for a reactor channel 150 mm long and 31 mm in diameter, with a constant pitch of the protrusions along the channels of 20 mm and protrusion heights h of 1 to 4 mm for 419 ≤ Re ≤ 2795. Compared to a smooth channel, a channel with protrusions increases heat transfer by an average of 2.23 times. By comparing the heat exchange parameters and the hydraulic resistance of the heat exchange channels, it was determined that h = 2 mm and 838 < Re < 1223 is the combination of parameters providing the best energetic mode of reactor operation. In general, an increase in h and coolant flow rate resulted in an uneven increase in heat transfer intensity. However, as h increases, the dead zone effect behind the protrusions increases and the rough channel working area decreases. Furthermore, increasing Re > 1223 is not advisable due to the increased cost of maintaining high coolant velocity and the reduced heat transfer capacity of the channel.

Thermal interaction between oil and gas wells and permafrost rocks leads to their thawing which can cause infrastructure deformation, greenhouse gas emissions, and landscape degradation. This paper presents a simplified engineering method for estimating the thaw radius around a cylindrical well with a constant wall temperature. Based on the Stefan condition and a quasi-steady-state temperature distribution in the thawed zone, an analytical formula (Equation 9) is derived. This formula explicitly relates the thaw radius to the well radius, thermal conductivity of the thawed soil, ice content, and latent heat of fusion, wall temperature, and time. The method accounts for the heterogeneity of the geological profile by identifying intervals with average thermophysical properties. Calculations for typical permafrost conditions (loam, ice content of 0.3, initial temperature - 2 °C, wall temperature - 5 °C) show that the thaw radius reaches 4.3 m after three years and exceeds 14 m after ten years at a wall temperature of 6 °C. Ice content slows down thawing, while high thermal conductivity accelerates it. The proposed formula has been verified by comparison with a finite-difference numerical model and the Kutasov–Eppelbaum method; the discrepancy does not exceed 15 %, which is acceptable for conservative engineering estimates. The method is suitable for rapid calculations to account for depth-dependent variations in permafrost properties. The results contribute to sustainable infrastructure design in permafrost regions by enabling quantitative assessment of safe well spacing, selection of operational regimes, and well thermal protection methods.