Purpose. To rationalize well washing by considering the influence of the annular channel limitation, granulometric composition of the mud, limitation of the joint movement of mud particles, drill string rotation, shape of the movement channel, and rheological properties of a cleaning agent. Methodology. Applied laboratory studies on the properties of drilling fluids are carried out using modern methods of analytical analysis and experimental studies, in particular, by using general principles of mathematical and physical modelling, methods of processing the results of studies in the EXCEL, MATNSAD environment, control and measuring devices of the laboratory of washing liquids of the Department of Oil-and-Gas Engineering and Drilling of Dnipro University of Technology (hydrometer, viscometer, plastometer, stalagmometer), and materials (technical water, clay bentonite powder, reagents, stabilizers and activators, surfactants as well as equipment and laboratory base of “Ukrnafta” PJSC to carry out certain stages of research. Findings. The properties of surface-active substances and activated washing liquids are analyzed. The main technological properties of drilling fluids are studied. Comprehensive information on the physical and chemical ability of flushing drilling fluids is provided. The main technological measures ensuring the stability of drilling process using activated-surfactant drilling fluids are considered in detail. The main technological principles of determining rational formulations of a selected cleaning agent in the circulation of Newtonian liquids are formulated and substantiated. A detailed description of surfactants, their properties and methods to study the formed solutions is given. Originality. The process of a rock-breaking tool on the well bottom will be stable in the conditions of dynamic equilibrium of the rock-breaking processes and removal of broken products into the annular space. Therefore, for a correct understanding of wellbore washing issues, basic regularities are established of the specified processes and the influence of various factors on these processes. Practical value. It has been proven that in order to give a drilling fluid the necessary properties that, on the one hand, will ensure an increase in the efficiency of rock breaking on the well bottom, and, on the other hand, will create favourable conditions for stable removal of cuttings onto the surface and maintenance of the well walls in a stable condition, it is necessary to apply different methods, in particular chemical activation as well as magnetic, thermal and electrochemical activation, in its different varieties.

Purpose. To analyse certain complex components of the rock breaking act during the well construction stipulated by the design features of the technical means of hydromechanical drilling and diversity of manifestations of hydraulic and physicochemical properties of the activated circulation medium. Methodology. Physicochemical parameters of the process of active substance adsorption from the water solutions on the rock surfaces were studied in terms of their disperse material by identifying optimal ratio in the solid phase particles volume of the activated solution group with the recording of time interval of the adsorption equilibrium establishment. Features of bottomhole processes in terms of the operating modernized facilities of hydromechanical drilling were considered involving up-to-date methods of analytical analysis and experimental-laboratory studies, i.e. by using certain techniques of mathematical and physical modelling, methods for processing and interpretation of the research results by means of SolidWorks, STATGRAPHICS, D, and control-and-measuring equipment and materials. Findings. The peculiarities of the combined hydromechanical drilling technique have been analysed from the viewpoint of the creation of the most efficient conditions of bottomhole rock breaking. Since a considerable degree of the development of breaking processes is the practically proved factor of hydromechanical drilling, the rationalization and intensification of those processes may be achieved by means of controlled physicochemical effect of the surface active medium. The experimental study was carried out to analyse the directedness of the development and results of surface interaction adsorption within the boundary of phase separation as the main factor of intensification of the rock mass breaking. A comparative analysis was performed concerning the surface activity of the corresponding substances that differ in their schemes of dissociation in a water solution whose properties are to be corrected additionally to make them close to the ones peculiar for natural drill muds. Positive influence of the adsorption phenomenon on the results of contact interaction of breaking elements of hydromechanical facilities was examined; this phenomenon is shown in the decelerated wear of metal surfaces. Originality. Useful influence of the physicochemical properties of the substances under consideration decreases beginning from the ionogenic anion-active sulfonol towards the ionogenic cation-active katapin K and to the non-ionogenic substance OP-10 (-10). However, in terms of combining the compositions of the mentioned substances, it can be strengthened additionally. Practical value. The indicated laboratory and experimental studies are the basic ones to design the mode parameters of the washing programme for a hydromechanical drilling well; they belong to the main output data used while substantiating the design and technical-technological parameters of the modernized pellet impact devices.

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. Development of a methodology for optimizing the technological parameters of the airlift operation, based on the analysis of the pressure balance in the annulus and in the drill string that occurs during drilling. Methodology. The tasks were solved by a complex research method, which includes a review and generalization of literary and patent sources, analytical studies on existing methods for optimizing the technological parameters of drilling with reverse circulation using an airlift. Findings. It has been established that in the study on the airlift circulation method during rotary drilling with reverse circulation, an important role is played by the analysis of the pressure balance arising in the course of drilling in the annulus and in the drill string. It takes into account both hydrostatic pressures and pressure losses for pumping water and water-air mixture. A technique has been developed for assessing the effect of rate of penetration on circulation parameters. Originality. For the first time, it has been shown that the analysis of the pressure balance makes it possible to establish, with a given accuracy, the average effective values of the output parameters: the density of the water-air mixture, its upward flow rate, and the air flow rate at a given velocity of the upward flow of water as it approaches the mixer. Practical value. The proposed technique makes it possible to establish the dependence of the values of the output parameters on the depth of the well, as well as the required compressor performance to provide a given drilling fluid flow rate.

The object of the study reported in this paper is the parameters of a device for implosion impact on aquifers during well development. The problem of increasing the productivity of aquifers was solved by removing colmatation products formed during the drilling process and restoring the natural permeability of the formations. This could ensure high production of wells and their long-term trouble-free operation. One of the most effective ways to develop wells is implosion impact. However, its use is hampered by the complexity of the structure of existing devices, the high cost of use, and the insufficient reliability of their operation. To overcome this, an original device for implosion impact on aquifers was designed and its operating parameters were determined. A procedure has been devised for determining the maximum permissible sizes of intervals not filled with liquid under the conditions of preventing casing string collapse. The effect of these intervals on reducing the total weight of the casing string was investigated. An optimal well structure was proposed for the conditions of the Tonirekshin field. The critical dimensions of empty intervals were calculated for all wall thicknesses of casing pipes included in the well design. It has been established that the amount of weight reduction of the casing string in the well due to the Archimedean force for field conditions is 43–47 %. Archimedean force increases with increasing pipe wall thickness. Reducing the weight of the casing string reduces the required winch power, allowing the use of lighter drilling rigs. The procedure for preparing for repeated implosion impacts has been studied. The studies performed and the recommendations presented will be effective when drilling and developing wells under the conditions of the Mangistau Peninsula, at the Tonirekshin field.