For the sake of ensuring the energy security of Ukraine, the trouble-free operation of the oil transportation system becomes of strategic importance. The problem is exacerbated in connection with the long service life of individual objects of the system, which leads to degradation of the properties of the pipe material due to corrosive and erosion processes, which is enhanced by the effect of time-varying loads. Today, in world practice, various methods are used to strengthen defective sections of pipelines: installation of steel, plastic and fiberglass couplings, winding of an elastic composite tape, the use of reinforcing composite couplings, etc. To study the effect of microcracks, corrosion and erosion defects on the Druzhba oil pipeline of OJSC Ukrtransnafta with an installed bandage, full-scale tests of a defective section of a pipe (material - 17GS steel) reinforced with bandages made of a similar material using a UI1 / 200 GK installation were carried out. As a result of research, the pressure of its destruction was determined. During the tests, strain gauging was used to determine pipe deformations. Comparison of the values of stresses obtained experimentally and analytically confirmed that the use of bands on defective sections of the pipeline is an effective means for extending their service life. For a more accurate and detailed analysis of the reliability and durability of oil pipelines, a study of the defective parts (break point) cut from the pipeline was carried out. As a result of the studies carried out on the models - "cutouts", corrosion defects with a depth of up to 5 mm were registered, which is about 55% of the loss of metal, however, the pipe was not destroyed by these defects, but by a defect of the "crack" type. To obtain the profile of the defect from the model - "cutout", scanning was carried out using a sensor fixed on a mobile tripod connected to a computer via an ADC. At the next stage of research, the assessment of the residual resource was carried out using the analysis of full-scale kinetic curves of damage to hazardous sections of the oil pipeline through experimental studies of models - "cutouts". A fatigue curve has been constructed, which can later be used to predict the fatigue life of such elements.

The rapid development of well construction technologies is inherently associated with the improvement of the technology that is used in this case. Tools of a new generation - bits with diamond cutters (PDC) - are widely used, in which technical and economic indicators are significantly better than roller cone bits. Although their design is well developed, the issue of optimizing the operation parameters of jetting nozzles, the design features of which determines the efficiency of well construction, remains relevant. Despite the effectiveness of the existing design of PDC bits, the study of hydrodynamic parameters was carried out using simulation modeling. Such a study makes it possible to assess the hydrodynamic parameters of the bit, develop recommendations for their improvement, which in turn will improve the efficiency of well construction in general. Computer programs designed for simulation of hydrodynamic processes make it possible to determine the necessary parameters with great reliability. However, the accuracy of the obtained result will depend not only on the settings of the grid of finite volumes, the number of iterations, but also on the initial data. Therefore, in the calculation model, in addition to the main parameters, such as the flow rate of the drilling fluid, the pressure at the bottom of the well, the bit rotation frequency, density, temperature and model of the drilling fluid viscosity, the roughness of the surfaces of both the bit and the walls, and the bottom of the well are taken into account. As a result of simulation, the drawbacks of the existing designs of PDC bits were identified, which can be eliminated using the proposed design of the jet nozzle, which: creates a large vorticity of the fluid flow, which positively affects the capture and removal of cuttings; makes it possible to regulate the direction of fluid movement (especially important for nozzles that are located farther from the bit axis), which will improve the removal of cuttings and, accordingly, will prevent it from re-entering the bottom

Purpose. Development of a method for simulating the screwing torque/moment and researching the design of double-shoulder threaded joints while preserving their geometric parameters. Determination of the optimal length of the additional shoulder pin part for the developed drill collar (DC) of NC50, NC55 type of various standard sizes. Establishing the dependence between the pin part length of the additional shoulder and other geometric parameters of the double-shoulder joint of the DC for further use when developing other standard sizes of similar design threads. Methodology. The development of design and the method for simulating the screwing torque of double-shoulder threaded joints was carried out using the finite element method and parametric modeling. Finding. A method for simulating the screwing torque of threaded joints was proposed and developed, which made it possible to improve the model of their automated design. The optimal lengths of the pin part of the additional shoulder of the developed design of double-shoulder threads of the NC50, NC55 types were determined. For planning threaded joints of similar design with the above-mentioned types of threads, a dimensionless coefficient was derived and its value was calculated. A nomogram was built to determine the length of the joint additional shoulder pin part due to the value of this coefficient. Originality. The model of automated design for double-shoulder threaded joints of drill string parts has been improved. This model preserves their geometric parameters and enables modeling a wide range of standard sizes of similar joints. Practical value. The optimal geometric parameters of the developed structures of double-shoulder threaded joints of the drill string elements were determined. A nomogram was built to determine the length of the additional shoulder pin part of the joint by the value of the dimensionless coefficient.

On the basis literary sources analysis, it was defined, that failures of the pump rod threaded connections are the most common exceed one-third of the total number of the rod string failures. It is due to non-uniform load distribution across thread turns of the pump rod threaded connections. The simulation modelling of standard design of pump rods was performed and graphic dependencies of stress distribution were developed on the gaps the pump rod threaded connections. The methods to reduce load non-uniformity across thread turns of the pump rod threaded connections were considered. The design of the pump rod connection was proposed; it shall have the variable mean diameter of the nipple thread by adding one more element, fitted in the nipple body hole.  The comparison of stress distribution dependencies on the gaps the pump rod nipple of the standard and proposed design showed that stress decrease in the first gap of the thread turn by 60  MPa, and in the third and next turns stresses increases and become uniform by the value. This change of stresses on turn gap, when it is operated in the well.

Today it is impossible to imagine drilling wells without the use of threaded connections. Despite continuous improvement of these threaded connections, their accident rate does not decrease. The peculiarity of operation of threaded joints of drill string elements is the impact of significant torsional, bending moments and tensile and compression loads on them. That is why the research of their stress-strain state is still important. To determine the stress-strain state of a threaded connection, in which there are deviations of one of the most important thread parameters, namely, the location of the main plane, a three-dimensional model of the NC50 connection has been constructed for study using the finite element method. As a result of the simulation of the thread connection, the main plane of which is placed in accordance with the requirements of regulatory documents, the distribution of stresses on the thread hollows of the nipple has been established, according to which the maximum stresses occur in the hollows of the coils placed closer to the supporting face, and then gradually decrease. This distribution of stresses obtained by simulation coincides with the known theories. Performed simulations, in which the placement of the main plane shifted by 2 mm toward the supporting face of the nipple showed a change in the distribution and growth of the value of stresses on the thread troughs of the nipple and the change in the value of the contact pressure at the supporting ends of the nipple and socket. It is worth noting that such changes will adversely affect the operation of the thread connection. The study of a threaded connection in which the main plane is displaced by 2 mm away from the bearing end of the nipple showed an increase in stresses along the troughs of the threads of the nipple and a sharp decrease in the values ​​of contact pressure at the bearing ends of the nipple and coupling. Under these conditions, the threaded connection will fail in a small number of operating cycles.