The emergence and impact of relaxation oscillations on the oil and gas drilling strategy has been studied very little, while their importance cannot be underestimated. The dynamic equilibrium in the system of the drill string - drive is determined by the energy balance between the energy consumption of the drill string during its operation and the power of the drive motor. In case of violation of this equilibrium state on the part of energy consumption relaxation oscillations may occur with consequences in the form of emergencies. In this regard, the determination of the influence and the need to take into account the relaxation oscillations in the drill string - drive system in the calculation of drilling strategy are extremely important tasks. According to experimental data, the selection of power from the drive motor in the event of relaxation oscillations can reach about 47%, which leads to a violation of the energy balance in the drill string - drive system and, as a consequence, appearance of self-oscillations of the drive motor power. The proposals on compensation of relaxation oscillations in the drill string - drive system by the Yagubov – Perminov method are considered.

Keywords: drilling strategy; relaxation oscillations; dynamic equilibrium; energy balance; torsional self-oscillations

The design of the magnetic separator meant to extract the emulsified oil droplets from reservoir water with the use of nanodispersed particles of magnetite and non-uniform magnetic field is proposed. The method for estimating the performance of the magnetic separator in the structure under consideration and the selection of optimal parameters is described in detail.

Keywords: magnetic separator; neodymium magnet; highly dispersed magnetite; emulsified oil; ferromagnetic cartridg.

In this paper, a method of static shear stress measuring for waxy crude oils in the temperature range, where their non-Newtonian properties are manifested as structured disperse systems, is proposed and tested. The method is based on the measurement of the shear stress dependence on deformation at a constant shear rate in the range 0.1 – 0.01 s^-1  with CR type rotary viscometer. The influence of such factors as temperature, mixture composition, time of thixotropic hardening, the presence of depressant additive and heat treatment on the static shear stress of oil from the USA-Ukhta MN is experimentally shown.

Keywords: controlled shear rate rheometer; depressant additive; heat treatment; waxy crude oil; yield stress; thixotropy.

Qualitative drilling-in is the key to further effective operation of oil and gas wells. Technically and technologically, this can be achieved by reducing the differential pressure and creating a protective «shield» on the wellbore wall, preventing penetration of the drilling fluid with the cuttings into the productive formation. For these purposes a bottomhole assembly is recommended, which includes a jet pump and a jet colmatator disposed above the bit. The article describes an improved method for calculating the jet pump with colmatator given downhole conditions during the drilling process. As an example, the parameters of the jet pump are determined and its operating characteristic is presented. The possibilities of optimizing the operating parameters of the jet pump by changing the colmatator’s nozzle diameter.

Keywords: drilling; primary opening; differential pressure; fluid coating; jet pump; hydraulic calculation; head; nozzle; mixing chamber; diffuser

The stress-strain state in the region of a single dent and in the area of a dent interacting with a metal loss defect is experimentally investigated. The object of research was a pipe (outside diameter is 114 mm, wall thickness is 4.5 mm, length is 1 m) with artificially made dent and loss of metal. The experiments were carried out on a laboratory stand to generate internal pressure in the pipe and measure deformations in the pipe wall. Dependences of hoop and longitudinal deformations on the internal pressure for different points of the dent region, as well as the distributions of hoop and longitudinal deformations in the axial and circumferential directions of the pipe in the dent region are obtained. The criterion for determining the combined defect «dent with metal loss» is recommended to use.

Keywords: deformation; stress intensity; combined defect; metal lossr; dent.

During the operation of main pipelines, it is possible to change the initial position of the pipe and the occurrence of bending stresses, which can make a significant contribution to the stress-strain state of the pipeline in operation. The accuracy of the determination of bending stresses and the conclusion about the pipeline section performance is ensured by the accuracy of the calculation of the bending radii of its axis. The results of the studies showed that increasing the interval between the control points used to calculate the bending radius of the axis of the pipeline increases the error in determining the actual bend radius. The most significant error in determining the radius of bending of the pipeline axis is observed in areas of small curvature and in points adjacent to such areas. When determining the bend radius, the interval between the points of control should be taken equal to 10 … 20 m, the non-uniformity of interval between adjacent points should be minimal.

Keywords: pipeline; axis configuration; control points; step; bending radius; bending stresses; accuracy of values.

The paper presents a method of coercimetric analysis of the stress state in the pipeline wall at the inlet and outlet sections of the aerial cooler apparatus (ACA) of the gas compressor unit and compares the obtained values of longitudinal and circular stresses with the calculated results obtained on the basis of the finite element method, as well as with the results based on the experimental determination of stresses by means of hardness measurement. The obtained results indicate that these methods of coercimetric analysis allow adequately describe the stress state at the control points at the inlet and outlet of the ACA. The development of this method will allow the express analysis of the stress state in the elements of the structures of existing compressor stations and other objects of the gas transportation system (GTS), which will provide a significant economic effect to the enterprises of the gas industry due to reductions in the cost of maintaining and repairing the functioning elements of the GTS.

Keywords: coercimetric analysis; coercive force; finite element method; solidometry; pipeline; air cooling unit section; annular and longitudinal stresses.

As a result of a probabilistic solution of the stability condition, using the quadratic approximation method, an expression is obtained for the mathematical expectation of the diameter of the core axisymmetric shell used in the oil and gas industry, according to the required standard reliability condition, when the soil bed ratio, Young's modulus and diameter are random variables and obey the normal distribution law . The influence of the variability of the design parameters on the reliability of the core axisymmetric shell (oil and gas pipeline) by the criterion of stability is investigated. The algorithm allows at the design stage of the object in question to evaluate the design position of the oil and gas pipeline in weakly bearing soils, which will reduce the risk of accidents due to possible loss of stability.

Keywords: oil and gas pipeline; stability; reliability; weakly bearing soil; pipeline, emergency risks; pivotal (core) axisymmetric shell.

The paper considers ways to optimize contractual relations with grid companies for the supply of energy sources. At present, the most common form of relations between suppliers and consumers of resources causes penalty payments not only with increased energy consumption, but also with reduced values of resource consumption. Analysis of operational data showed that almost half of all equipment failures occurs without the appearance of any characteristic trends. It is extremely difficult to predict interruptions in the energy consumption of the corresponding equipment by parametric methods. Taking into account the probabilistic nature of the work and failures of the pumping and power equipment of oil and gas enterprises, the use of game theoretic methods is most expedient for forecasting the volumes of energy consumption.

Keywords: maximin; minimax; matrix of winnings; strategy; degree of risk; savage, Valda, Hurwitz criteria.