http://elar.nung.edu.ua/handle/123456789/6382 The scientific journal 2026-04-05T19:07:14Z http://elar.nung.edu.ua/handle/123456789/6389 Title: Quality control of surfactants for oil and gas extraction intensification Authors: Chuiko, M. M.; Vytvytska, L. A.; Stankovska, І. М. Abstract: The method of express control of the degree of rocks wetting by surfactants solutions and formation fluids while intensification of oil and gas extraction by controlling and regulating the interphase parameters at the formation fluid-rock – surfactant water solution interface in the process of bottom hole zone treatment has been sugggested. The basis of the proposed method is the dependence of the change in the impedance of the capacitive cell, which contains the studied fluids and specimens of the rock, on their wettability properties, which, in turn, determine the rate of dispersion of the solution on the investigated surface. The main informative parameter of the proposed method is the rate of impedance change, which is determined by the angle of inclination of the graphic dependences of the change of impedance in time when the solution of surfactant is being spread on the solid surface. To implement the developed impedance control method, a device was developed and a method of grading the degree of wettability for a comprehensive evaluation of the quality of surfactants and the selection of such surfactants that have the most optimal wetting properties for specifically-taken oil and gas rocks has been developed. 2017-01-01T00:00:00Z http://elar.nung.edu.ua/handle/123456789/6388 Title: Corrosion degradation of pipeline steels with different strength grades Authors: Zvirko, O. I. Abstract: Ukrainian gas mains steels, taking into account their age, are subjected to aging and degradation, which leads to deterioration of their properties, especially mechanical ones. Degradation of mechanical properties of steels is intensified by corrosion in the course of which hydrogen evolves and is absorbed by metal, so the metal becomes embrittled. The aim of this work is to define susceptibility of pipeline steels with different strength grades to corrosion degradation during their long-term service. The comparative studies of corrosion and electrochemical behaviour of low alloyed gas pipeline steels with different strength grades in NS4 aqueous solution, simulating soil environment, has been carried out. Pipeline steels with three strength grades in different states – in the as-received state and after long-term operation have been investigated. The influence of long-term operation on corrosion and electrochemical properties of steels has been analysed. It has been found that the 17H1S steel (steel is equivalent to X52 strength grade) is characterized by the lowest corrosion resistance among the studied steels, and the highest corrosion resistance is typical for the X70 steel in both studied states. Corrosion and electrochemical characteristics of pipelines steels with different strength grades in the NS4 environment have been significantly deteriorated due to long-term service. It has been found out that degree of corrosion degradation caused by long-term operation of gas mains is the highest for the high strength X70 steel. Electrochemical activation of pipeline steels caused by their long-term service comes out in an increase of cathode and anode processes intensity, increase of corrosion current density, decrease of polarization resistance and in a shift of corrosion potential values towards more negative ones for degraded steels compared with steels in the initial state. 2017-01-01T00:00:00Z http://elar.nung.edu.ua/handle/123456789/6387 Title: Numerical prediction of the current and limiting states of pipelines with detected flaws of corrosion wall thinning Authors: Milenin, O. S. Abstract: The main assumptions have been made for the physical and mathematical models of combined development of the stressstrain state and voids of ductile fracture in welded pipeline elements and pressure vessels with the detected 3D metal discontinuities (local corrosion losses of metal, macrovoids), including the ones located in the area of site welds for determination of the characteristic features of defective structures’ limiting state. Analysis of the stress-strain state of the welded pipeline section has been carried out based on finite element solution of the problem of non-stationary thermoplasticity by tracing elastic-plastic deformations from the beginning of welding to the complete cooling of the structure and subsequent loading to the limiting state. The continuum dilatation model of fracture is based on a stepwise prediction of micro- and macro-damage of material both in welding and under loading with internal pressure and external force bending moment to the limiting state on the basis of the Gurson–Tvergaard–Needleman theory. The criteria for macroscopic fracture of structure on a brittle-ductile mechanism have been proposed. Methods for probabilistic estimation of the stressed state of the pipeline structure from the point of view of fracture susceptibility, which are based on the integration of the calculated field of principal stresses within the framework of the Weibull statistics, have been developed. Functional dependences of Weibull coefficients on the properties of the metal, namely yield stress and degree of strain hardening, were obtained for correct quantitative assessment of the state of critical structures based on a complex analysis of the limiting state of steel pipelines under internal pressure. Specific features of the limiting state under loading with internal pressure and bending moment have been investigated based on an example of typical cases of operation damage of main pipeline elements such as local metal losses in the area of the site weld. It was shown that nature of interaction of residual post-weld stress state of metal with operation stresses from the geometry concentrator significantly affected the value of limiting pressure in the pipe. Besides, effect of the additional bending moment on load-bearing capacity of the pipeline section with isolated flaw of local corrosion wall thinning has been determined. The change of failure probability of the structure as a result of internal pressure and bending moment loading at various geometry dimensions of thinning flaw has been investigated based on the results of integral analysis of the pipeline flawed section state. 2017-01-01T00:00:00Z http://elar.nung.edu.ua/handle/123456789/6386 Title: Development of non-marking tubular holding equipment Authors: Kopey, B. V.; Liakh, M. M.; Liakh, Yu. M.; Mykhailiuk, V. V. Abstract: The article gives the recommendations of a technical solution for preventing the destruction of external surfaces of drill and casing pipes by wedge grippers in the process of performing descending-lifting operations. Also, a constructive solution to clamping the surface of the pipes during screwing or unscrewing of thread connections is proposed. The research of proposed technical solutions of grippers using computer models has been carried out. The main parameters of the design elements of the proposed wedge gripper and clamp are established, which can provide the technological process without destroying the outer surfaces of the pipes of the oil assortment. 2017-01-01T00:00:00Z