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Date submitted2020-05-25
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Date accepted2020-06-11
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Date published2020-12-29
Technological aspects of cased wells construction with cyclical-flow transportation of rock
- Authors:
- Andrei S. Kondratenko
A high-performance technology for constructing cased wells is proposed. Essence of the technology is the advance insertion of the casing pipe into the sedimentary rock mass and the cyclical-flow transportation of the soil rock portions using the compressed air pressure supplied to the open bottomhole end of the pipe through a separate line. Results of mathematical modeling for the process of impact insertion of a hollow pipe into a soil mass in horizontal and vertical settings are considered. Modeling of the technology is implemented by the finite element method in the ANSYS Mechanical software. Parameters of the pipe insertion in the sedimentary rock mass are determined - value of the cleaning step and the impact energy required to insert the pipe at a given depth. Calculations were performed for pipes with a diameter from 325 to 730 mm. Insertion coefficient is introduced, which characterizes the resistance of rocks to destruction during the dynamic penetration of the casing pipe in one impact blow of the pneumatic hammer. An overview of the prospects for the application of the proposed technology in geological exploration, when conducting horizontal wells of a small cross-section using a trenchless method of construction and borehole methods of mining, is presented. A variant of using the technology for determining the strength properties of rocks is proposed. Some features of the technology application at industrial facilities of the construction and mining industry are considered: for trenchless laying of underground utilities and for installing starting conductors when constructing degassing wells from the surface in coal deposits. Results of a technical and economic assessment of the proposed technology efficiency when installing starting conductors in sedimentary rocks at mining allotments of coal mines are presented.
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Date submitted2019-11-20
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Date accepted2020-01-20
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Date published2020-10-08
Effect of shear stress on the wall of technological pipelines at a gas condensate field on the intensity of carbon dioxide corrosion
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.
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Date submitted2020-05-06
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Date accepted2020-05-24
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Date published2020-06-30
Revisiting the evolution of deformation zones under platform conditions in the case study of the Kungur Ice Cave (Cis-Urals)
- Authors:
- Nataliya V. Lavrova
Observations in mining tunnels and caves allow to identify composition and development specifics of fault structures under subsurface conditions at various stages of geological history. Basing on the existing formation model of Kungur Ice Cave karst system, author examines the transformations of deformation zones, occurring in the mass of interlaid sulfate and carbonate rocks under platform conditions. Morphologic specifics of vertical structures – organ pipes, developed within one of the gypsum-anhydrite units, are defined by evolution stages of disjunctive faults, penetrating the entire rock mass of the Ice Cave. Point infiltration of surface waters and formation of a single channel, where rock softening and taluses from overlapping deposits gradually occur, are currently considered to be the initiators of pipe formation. At a later stage a sink forms on the surface, increasing the amount of water coming to the karsting mass. However, the size of debris in the talus, incommensurate with the pipe head, rounded arches of separate pipes, fragments of feeder channels, characteristic for artesian conditions of underground water circulation, faceted rock debris from overlapping deposits, specifics of wall structure all define the priority of pipe formation over grottos and cave galleries. Plastic properties of gypsum sediments and processes of their hydration define secondary modifications of pipe walls up to complete filling of the voids and formation of secondary pillars with subsequent renewed formation of vertical channels – significantly smaller in diameter and formed by infiltration waters when subject to corrosion.
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Date submitted2018-05-21
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Date accepted2018-07-14
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Date published2018-10-24
Increasing the wear resistance of adapters and drill pipes by elec-tromechanical processing
The directions of the research on increasing the wear resistance of drill pipe locks, threaded joints and casing drill string have been defined: application of drill pipes from the nose-resistant surfacing to the lock with Russian and foreign materials (hardbanding); hardening of the surface layer of drill pipe locks by electromechanical processing; hardaning of the external and internal locking thread of drill pipes by electromechanical processing. Comparative tests of the wear resistance of various hardening materials (hardbanding) of Russian and foreign production and the drill pipe lock without surfacing have been made. The recommendations for increasing the wear resistance of threaded joints by the method of electromechanical processing are developed, which determine the ways of increasing the resource and reliability of drill pipes and sub-assemblies, the formation of unique properties of parts, reducing the labor-capacity of manufacturing and restoring parts, increasing the efficiency of enterprises and organizations, protecting the environment and creation of competitive products. The materials of the article are of practical value for specialists of various fields engaged in the issues of increasing the reliability of technological equipment. The production success of using wear resistant surfacing technology on the body of a drill pipe joint is due to the possibility of using relatively simple and mobile welding equipment, carrying out work in the places of use of a drilling tool or temporary (permanent) production bases with a small transport arm from the field, re-depositing surfacing materials restoration of drill pipe locks; a wide and growing list of companies that receive accreditation for the production of these works.