The problems of traction properties increase in locomotives are considered. The necessity in devices for instantaneous control of a friction coefficient of wheels and rails based on the impact of electric current or a magnetic field upon a wheel/rail contact area. There are defined basic fields of researches essential for the actual realization of such devices. It is defined that devices based on electric current impact require the introduction of considerable changes in the units of a crew part for wheel pair insulation and searches of problem solution in the separation of traction current and control one and the prevention of control current impact upon alarm systems. It is offered to consider magnetic amplifiers of adhesion as a solution of a short-term outlook which can be introduced in an existing locomotive fleet and those using current impact as a solution of newly-developed promising machines. There is offered a design of an individual traction drive simplifying a problem in the arrangement of devices for instantaneous control of a friction coefficient.

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The influence of reservoir rock properties on sand production in wells is considered. It was concluded that the rock should be considered rather not from the point of view of its strength, but from the point of view of the type of cementitious substance and its distribution. When predicting sand production, it is necessary to take into account the internal stresses of the rocks, as well as the change in these stresses during drilling, perforation and operation of the formation due to the violation of their initial state. Within the framework of this work, an analysis of the main causes of sand production during the operation of gas wells and the negative consequences of sand production for gas production equipment is presented. It has been established that water breakthrough, formation depletion, pressure drop at the bottom of the wells due to their frequent shutdown are the main prerequisites for the removal of sand from the bottomhole formation zone. Sand production is associated with such negative consequences as plugging in wells, erosion of underground and surface equipment, collapse of the top of the bottomhole formation zone and production strings. The main technologies for the prevention and elimination of accidents associated with the removal of mechanical particles from the reservoir are considered. Based on the research results, an algorithm was proposed for selecting technological modes of well operation in conditions of water and sand. The parameters for choosing the optimal operating mode of a gas well are substantiated, in which sand is not extracted with the subsequent disabling of downhole and wellhead equipment, the integrity of the bottomhole zone is not violated, and the well is not selfcontained. The results obtained can be applied to improve the efficiency of gas wells operation and predict their trouble-free operation.

During the entire development of an oil and gas field, it is necessary to carry out a complex of various studies aimed at identifying the parameters of the productive layer. One of such studies is the analysis of core material, as a result of which the following parameters of the rock are determined: porosity, permeability, Young's modulus and others. The listed characteristics must be taken into account when building a geological and hydrodynamic model of a field. In addition to these parameters, the strength properties of the rock should be determined, since they are necessary in the design of the wellbore. Such characteristics can be obtained by conducting research in specialized laboratories. This is not always possible due to various reasons. A number of studies confirm the fact of the relationship between the acoustic properties of a rock (the velocity of the longitudinal and transverse waves) and the strength characteristics. The acoustic properties of the rock must be taken into account when interpreting the acoustic logs of the wells, which allows to reveal the distribution of rocks along the wellbore. Based on the velocities of ultrasonic waves propagation, it is possible to calculate the elasticity dynamic modulus, which let assess the tendency of the rock skeleton to compaction as a result of the effective stress action. Therefore, the determination of the rock acoustic properties is necessary when planning the development of a field and its implementation. The results of laboratory studies aimed at establishing the relationship between the strength and acoustic properties of rocks are presented. During the experiment, the dynamic Young's modulus was also determined and its relationship with the speed of ultrasonic waves propagation was revealed. As a result of laboratory studies, empirical dependences of the ultimate strength in volumetric compression (σс), elasticity dynamic modulus (E ) and the velocity of transmission of longitudinal (vp) and transverse waves (vp) were obtained. An assessment of the obtained values was given over the entire measurement range.