Purpose. Substantiation of the design solutions in separate units of the modernized hydromechanical devices and specification of rational technological modes of their operation in specific geological and technical conditions. Proposals on construction of wells by development and introduction of progressive methods and techniques. Methodology. Analysis of the peculiarities of the modernized hydromechanical drilling devices in terms of rock breaking is performed using modern methods of analytical analysis and experimental research, i.e. by using mathematical and physical modeling; method of modeling and processing of research results in the SolidWorks medium and others; control and measuring tools and materials. The process of solving the problems of optimal planning of the experiment was divided into four stages: development of a planned model; preparation of the necessary initial data; calculation of the model; obtaining and processing of the results. The well rock-breaking processes were modeled on a special-purpose laboratory stand equipped with a measuring and control unit (flow meter, manometer, tachometer, and coordinate spacer). Findings. The main ways to improve well hydromechanical technologies have been identified. The fundamental principles have been formulated concerning the process of design of such equipment schemes that will combine the most productive and efficient methods of the rock mass operations. A number of factors characteristic of the implementation of well hydromechanical technologies, have been identified, i.e.: rational range of physical properties of rocks according to which proper technical and technological characteristics of the devices are selected; structural use of mechanical rock-breaking organs of the devices; and operating parameters of the drilling process. It has been proved that the developed design schemes of hydromechanical drilling devices, in terms of their optimal technical performance and technological development, can be recommended for their use in the appropriate geological and technical conditions, where the implementation of other methods is inexpedient or limited. Originality. Formation of the peripheral part of the bottomhole is a subordinate factor determined by the device design; effective profiling is possible only due to the introduction of additional components into the hydromechanical drilling devices, which makes it possible to use certain technological methods. Practical value. The obtained results of laboratory and analytical studies are basic to design operating parameters of the well deepening processes by using the hydromechanical devices. Data from the study on bottomhole working processes of hydromechanical technologies are the starting point for the substantiation of design and technological parameters of modernized pellet impact devices.

Purpose is to substantiate design factors and technological parameters of next-generation facilities of hydromechanical drilling basing upon the determined features of interaction between breaking pellets and rock mass. Methods. The studies of directionality features and bottomhole processes for rock mass breaking have been carried out using the current analytical methods and laboratory experiments. Among other things, certain mathematical and physical simulation techniques, methods of theoretical processing and interpretation of the research results under SolidWorks, Statgraphics, and Маthсаd environments, and a number of relevant instruments and materials have been applied. Following their technological sequence, the well bottomhole rock-breaking processes were simulated using a special laboratory stand equipped with a control-and-measuring unit (inclusive of a flowmeter, manometer, tachometer, and coordinate spacer among other things). Findings. Application perspectiveness of the combined techniques for rock breaking has been proved. Structural designs of the next-generation facilities for well drilling have been proposed. The pellet-impact drilling features have been analyzed from the viewpoint of its significant dynamic component during the rock mass breaking. Nature of the effect of breaking load rate on the results of bottomhole deformation processes has been identified. Efficiency of the proposed scheme to improve pellet-impact drilling based upon maximum use of a well bottomhole deformed by pellets has been proved. Measures to increase technical and technological indicators of pellet drilling have been considered. Requirements for the conditions stabilizing operation of a collar of the pellet-impact device have been outlined. Further research tendencies have been specified. Originality. It has been determined that compliance with specific geometrical and hydromechanical ratios, corresponding to the stable mode of a well sinking, is the factor required for reliable operation of hydromechanical drilling facilities. Practical implications. The results of stand-based tests as well as analytical studies may become the foundations to develop efficient engineering decision for hydromechanical well drilling with high technical and economic indicators. The data, concerning bottomhole rock breaking processes, are the basic ones to work out rational standard parameters of well sinking processes.

Specialists of Dnipro University of Technology are among the leading researchers involved in studying the specifics of implementation and functioning of rational and energy-efficient schemes of organization of circulation processes while well drilling and operating. In particular, we have carried out thorough and comprehensive studies of physicochemical phenomena used while creating, preparing, and using the washing fluids. The purpose of the paper is to study and generalize the approaches to designing the parameters of hydraulic well washing programme under complicated geological and technical conditions, analysis of the factors of its correction basing on substantiation of analytical and research regularities of well circulation processes, and optimization of a component and quantitative composition of drill cleaning agents, which are aimed at the most efficient intensification of the bottomhole breaking processes. The development and implementation of a progressive complex hydraulic washing programme for wells under construction are analyzed involving modern methods of analytical analysis and experimental studies. The drilling circulation processes in a well were modelled in terms of experimental wells involving a drill rig UKB-4P and corresponding auxiliary tools and equipment.

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The problem of development of gas hydrate deposits is complicated by a range of problems connected with the adaptation of traditional methods and procedures to develop the mentioned type of raw materials. Construction methods of the directed well deserve high attention since they are the most efficient solution to provide a stable process of gas fraction production. Experts of the Dnipro University of Technology are at the top among the studies engaged in implementation and operation of gas hydrate deposits. Among other things, the experts have designed rational bottomhole assemblies of the directed drilling for the conditions of gas hydrate deposits. Such devices have a number of functional features. The paper describes following particularities being the most significant ones: a material to produce destructive balls and their physical properties; operating modes of a drilling process; directionality of bottomhole circulation processes as for the operational parameters of flushing fluids; and spatial location of well direction. Both calculations and bench tests favoured the process intended to identify functional features of the devices and proved convincingly the truthfulness of the initial theoretical foundations to drill the directed wells with the help of the modernized hydromechanical boring tool combined with a feeding device. The paper purpose is to analyze and substantiate structural solutions within the certain units of techniques for complex use as well as determine the rational operating schedules of the latter in the context of specific geological conditions where the directed wells are under construction.