Investigation of the mechanical properties and corrosion behaviour of hybrid L 80 Type 1 and duplex steel joints produced by magnetically impelled arc butt welding

In the field of deep geothermal energy, the mono-tube design will be increasingly used in the future, as significant cost savings can be expected in the production of boreholes up to depths of 6000 m. The previously used bolting of the pipe lengths by means of sleeves contributes significantly to the construction costs. In addition, there is an increased risk of failure for the sleeve bolting, especially if different materials have to be used in different layers for the purpose of increasing the corrosion resistance. Magnetically Impelled Arc Butt Welding (MIAB) was used for direct welding of pipe segments with complete elimination of socket bolting. In the process, the casing material (L80 Type 1), which is a cost-effective standard material, and a corrosion-resistant duplex steel (1.4462) were hybrid welded. The results show excellent properties both in terms of mechanical properties and corrosion resistance. It is shown that the advantages of the MIAB process in joining these different materials can successfully overcome the metallurgical challenges. This new approach for the production of borehole liners can contribute significantly to cost reduction in the construction of geothermal boreholes

Sorption materials for indoor environment cleaning from microorganisms

The article touches upon the problem of working area air pollution by pathogenic microorganisms. The problem’s solution requires increased efficiency of filtration materials. Using thermally expanded graphite and Cribrol® polymer composite material, we analyzed air purification quality of multifunctional rooms in comparison with traditional activated carbon. The filtration materials properties were studied using a set of analytical methods. The air was pumped through tested materials in a volume of 500–2000 liters with the use of PU-1B sampling device depositing microorganisms on the nutrient medium. We showed that activated graphite and Cribrol® are effective in cleaning the air from bacteria (cell sizes do not exceed 1 micron), as well as larger microorganisms (from 3 microns or more). Activated graphite completely trapped microorganisms in all test variants. The filtration capacity of the new materials turned out to be higher than that of traditional activated carbon, which indicates the prospects for their further research and practical application

Autoclave modeling of corrosion processes occurring in a gas pipeline during transportation of an unprepared multiphase medium containing CO2

The problem of selecting a method for ensuring the reliability of the unprepared fluid transport facilities of an unprepared fluid in the presence of carbon dioxide is considered. Carbon dioxide corrosion is one of the dangerous types of damage to field and main pipelines. It has been shown that dynamic autoclave tests should be carried out during staged laboratory tests in order to determine the intensity of carbon dioxide corrosion and to select the optimal method of protection. A hypothesis about the imperfection of the existing generally accepted approaches to dynamic corrosion testing has been put forward and confirmed. A test procedure based on the use of an autoclave with an overhead stirrer, developed using elements of mathematical modeling, is proposed. The flows created in the autoclave provide corrosive wear of the sample surface similar to the internal surfaces elements wear of the pipelines piping of gas condensate wells. The autoclave makes it possible to simulate the effect of the organic phase on the flow rate and the nature of corrosion damage to the metal surface, as well as the effect of the stirrer rotation speed and, accordingly, the shear stress of the cross section on the corrosion rate in the presence/absence of a corrosion inhibitor. The given results of staged tests make it possible to judge the high efficiency of the developed test procedure

Analysis of the reasons for the accelerated failure of oil pipelines in the regions of the Far North and Siberia

From about the time trends of development of oil gas complex of the country requires reassess the reliability and durability of pipelines for various purposes. The reason for this trend is the gradual displacement of the producing provinces towards regions with extremely low climatic temperatures, difficult natural conditions, and highly aggressive components of the oil production. Analysis of the reasons for the accelerated destruction of pipes in the northern regions of the country made it possible to identify two main causes of failure. This is the development of corrosion- mechanical defects and insufficient cold resistance and crack resistance of materials at low climatic temperatures. The paper analyzes the role of non-metallic inclusions in increased defectiveness of steel X70 pipes, an analysis of the influence of the microstructure and non-metallic inclusions of operation the pipes in cold climate

Complex Mathematical Modeling of the Well Drilling Process

Recently, the technologies for the global modeling of the process of oil well drilling have become widespread. Mathematical modeling is used in well design, virtual testing of various drilling equipment, simulations of various emergency situations, and personnel training. Complex modeling of the well drilling process includes the simulation of such phenomena as the dynamics of the drill string and its contact interaction with walls, the flow of the drilling fluid and its interaction with the soil (considering influxes and leakages), soil crushing by the drill, the transfer of cuttings particles by the drilling fluid, heat exchange with the soil, and others. This paper provides a detailed review of the existing modeling approaches to solving such problems. Most of the studies included in the review focus on building a detailed mathematical model of one or several of the above processes. Moreover, all these processes mutually influence each other, which also needs to be considered in the analysis. It appears that further development of such a multiphysics approach will be the main direction of research in this area in the near future

Structural heterogeneities of tube steels taken into account in the development of contactless magnetometry of pipeline systems

One of the problems facing gas and oil pumping companies is the aging of pipelines, whose service life is rapidly approaching, or even exceeding, the resource planned during design. The only possible way to evaluate the possibility of further safe operation and residual life of pipelines is to conduct studies of the actual state of the parent metal and welded pipe joints. However, the direct investigation of metal pipes is practically impossible due to the linear dimensions of objects and their position. The analysis of the state of the pipeline system can only be made with the help of contactless, most often magnetic methods. Interpretation of magnetograms and detection of defects that are dangerous for the operation of pipes is one of the most difficult problems facing defectoscopists, which can be solved only by creating a library of structures and defects. This paper presents the results of a structural analysis of the metal of pipes, which must be taken into account when interpreting the results of magnetograms. These results constitute a part of the library of defects in pipeline systems developed in SPbPU

Several erosion test results of means of sand control

When screens are used as the sole means of sand control, they function as a downhole filter. The entry of sand or other particles into horizontal and vertical wells presents the problem of steel erosion and productivity lost. Downhole is the most desirable location to restrict its access into the well. The problem of material reliability testing is relevant today, that’s why several erosion tests were made and studied. Self-made test bench allow varying velocity flow and fractions conditions (composition, quantity, size, hardness). Slurry erosion experiments resulted in wear of downhole sand control screens. The wear criteria were checked by weight loss of screen samples material and its integrity degradation. The idea of slurry erosion tests was to reveal screens wear

Predicting the durability of zinc coatings based on laboratory and field tests

Galvanizing is one of the most common methods of corrosion protection. For the deposition of zinc coatings used such methods as gas-thermal deposition, thermal diffusion saturation in powder, hot-dip galvanizing, cladding, and galvanic precipitating during electrolysis. The hot-dip galvanizing is the most common method, which is used in construction, automotive and other industries. Paper presents the results of research of zinc coatings used in sea conditions. The aim of the work was to determine an acceleration factor by comparing the corrosion rate in laboratory conditions with the data from field tests. Laboratory studies were carried out in a salt fog chamber. Samples were periodically removed from chamber to build the dependence of the corrosion rate on the exposure time. Field tests were carried out at the exploitation area. Result of the work is a guide that allows to predict the corrosion rates of zinc coatings using laboratory tests. The advantage of this test method is shorter time of exposure in comparison with field test

The Effect of the Operation of Downhole Equipment on the Processes of Corrosive Wear (by the Example Inflow Control Devices of Nozzle Type)

Existing approaches to assessing the reliability and safe operation of downhole equipment provide for assessing only the direct impact of erosion and corrosion processes on the degradation of the material. At the same time, the influence of downhole equipment operating modes on the intensity of corrosion and erosion processes is not evaluated. The necessity of using inflow control devices is shown. The necessity of selecting inflow control devices for specific operating modes of the well is highlighted in order to avoid increased erosion wear due to increased sand production. In this article, a series of studies was conducted to assess the influence of the hydrodynamic characteristics of the fluid flow, which vary depending on the operating modes of the nozzle-type inflow control device, on corrosion processes in the well. It was shown that the level of wall shear stress (WSS) of the base pipe, immediately after the flow control device in the direction of fluid flow, affects the intensification of corrosion processes in downhole equipment. Studies of WSS on the pipe wall were carried out using a dynamic autoclave and elements of mathematical modeling. The design factors (the angle of inclination of the main hydraulic channel of the inflow control device relative to the base pipe) affecting the change in tangential stresses on the wall of the base pipe were investigated. The mechanism of corrosion wear of the base pipe was revealed

Investigation of Factors Influencing the Autoclave Tests Results of Internal Anticorrosive Polymer Coatings

Polymer coatings are one of the most common methods for protecting metal structures from corrosion damage. For example, in the oil and gas industry, polymer coatings are used to protect the inner surfaces of oilfield pipelines. Forecasting the service life of the coating is an unsolved problem. Existing test methods allow to assess the quality of coating application and compliance with the declared properties, for example, resistance at a certain temperature, but do not allow to understand the expected service life or degradation dynamics. One solution to this problem may be the development of existing methods of autoclave testing of coatings with the addition of more criteria for assessing degradation. This paper considers the methodological features of autoclave testing with rapid pressure relief. The decompression autoclave test was considered from the point of view of the principles of its conduct and evaluation of test results. The tests were carried out in environments containing hydrogen sulfide and carbon dioxide. The main object of the tests was anticorrosive polymer powder coatings applied in industrial conditions. The work assessed the influence of the following factors on the test result: pressure relief time, test cycle, and coating quality. Attention was also paid to the evaluation methods; aside from the adhesion assessment, optical microscopy and the evaluation of the microhardness of coatings were used. As a result of the work carried out, it was shown that the pressure relief rate within 5 s affects the test results. An increase in micropores and a drop in the microhardness of coatings after cyclic autoclave tests were also shown. The method of assessing the degradation of coatings using microhardness also showed the convergence of the results with the traditional method of assessing adhesion. The results of the work can be used to modify the autoclave testing method and transition to resource forecasting