One of the pressing scientific challenges in the field of hydrocarbon production enhancement from hard-to-recover reserves using hydraulic fracturing is the insufficient understanding of how the elastic properties of hydraulic fracturing fluids affect proppant retention efficiency during fracture initiation in the near-wellbore zone. Earlier domestic and foreign studies on proppant transport capacity assert that fluid viscosity plays a key role in proppant retention; however, recent data indicate a significant influence of the elastic properties of polymer systems, particularly when using low-viscosity synthetic hydraulic fracturing fluids based on polyacrylamide (PAM). This study aims to provide a fundamental substantiation of the effect of viscoelastic properties of hydraulic fracturing fluids on proppant transport efficiency. The article presents the methodology and results of laboratory tests evaluating the viscoelastic and proppant transport properties of PAM-based and guar polymer-based hydraulic fracturing fluids. The findings demonstrate that PAM-based hydraulic fracturing fluids, despite their low effective system viscosity, exhibit more pronounced elastic properties compared to linear guar gels: the relaxation time and the first normal stress difference for the synthetic hydraulic fracturing fluid are 1.99 and 4 times greater than the corresponding values for the linear guar gel. The test results confirmed that the proppant settling rate in the PAM-based hydraulic fracturing fluid under static conditions was 28 times lower than that in the linear guar gel at equivalent active substance concentrations. The elastic properties of hydraulic fracturing fluids have a substantial effect on proppant transport capacity, supporting the potential of using low-viscosity synthetic PAM-based hydraulic fracturing fluids to enhance hydrocarbon production from reservoirs with permeability less than 1 mD.

The object of the study is a section of the gas and gas condensate collection system, consisting of an angle throttle installed on a xmas tree and a well piping located after the angle throttle. The aim of the study is to assess the impact of the flow velocity and wall shear stress (WSS) on the carbon dioxide corrosion rate in the area of interest and to come up with substantiated recommendations for the rational operation of the angle throttle in order to reduce the corrosion intensity. In the course of solving this problem, a technique was developed and subsequently applied to assess the influence of various factors on the rate of carbon dioxide corrosion. The technique is based on a sequence of different modeling methods: modeling the phase states of the extracted product, three-dimensional (solid) modeling of the investigated section, hydrodynamic flow modeling of the extracted product using the finite volume method, etc. The developed technique has broad possibilities for visualization of the obtained results, which allow identifying the sections most susceptible to the effects of carbon dioxide corrosion. The article shows that the average flow velocity and its local values are not the factors by which it is possible to predict the occurrence of carbon dioxide corrosion in the pipeline section after the angle throttle. The paper proves that WSS has prevailing effect on the corrosion intensity in the section after the angle choke. The zones of corrosion localization predicted according to the technique are compared with the real picture of corrosion propagation on the inner surface of the pipe, as a result of which recommendations for the rational operation of the angle throttle are formed.

The mining-transport equipment in technological schemes with application of the mobile crushing equipment represents difficult mining system with consecutive and parallel connection of separate technological elements. Reliability of system is defined on the basis of reliability of its components.