This paper is devoted to the history of exploration of sintezed and natural gas hydrate. Academic, engineering and energy periods of the history of gas hydrates studies are described. The most significant researches in this area are described. The main practical projects in the world for the study and production of gas hydrates are reviewed.
ВплиВ Витрати промиВальної рідини на контактну температуру при бурінні сВердлоВинPurpose. To establish the influence of drilling fluid circulation rate onto the contact temperature during the rotation drilling using an impregnated diamond drill bit; to verify the mathematical model of the diamond drill bit heating process in the course of boreholes drilling.Methodology. Bench experiments and theoretical analysis using methods of mathematical modeling. Findings. In the course of the bench experiments the data of influence of the drilling fluid circulation rate on the contact temperature during drilling of granite rock with a 59-mm diameter drill bit were obtained. A relevant mathematical model of the drill bit heating under the variable rate of drilling fluid was represented on the basis of a system of the heat transfer differential equations. A comparative analysis of experimental and predicted data was carried out, and its findings positively confirm the reliability of the mathematical modeling of heat transfer processes in the downhole during bore-hole drilling.Originality. The methodology of experimental measuring of the contact temperature during the bench experiment borehole drilling using resistance sensors was proposed herein. New experimental data was obtained which allowed establishing a correlation between the contact temperature and the rate of drilling fluid in the downhole area. The proposed mathematical model of the process is found to be adequate; it allows predicting the temperature mode on the working face of borehole in the course of drilling. The findings of the research make it possible to substantiate the effect of the diamond core drilling performance gaining due to transition from the fixed time operation parameters to the variable ones.Practical value. The regularities of action of the drilling fluid circulation rate on the contact temperature of the "tool -working face" system in the course of borehole drilling were established. The performed research confirmed the possibility of managing the thermal mode of drilling by variation of the drilling fluid circulation rate. The diamond core drilling performance gains, therefore, are possible to achieve by way of increasing the thermal stimulation of the mining rock. The developed mathematical model allows forecasting the contact temperature in the course of borehole drilling for various values of the drilling fluid circulation rates. Using of this model makes it possible to define the permissible diminishing of the drilling fluid circulation rate in order to prevent any abnormal thermophysical wear of the drill bit.Keywords
Purpose. To study the impact of pulse flushing on the power consumption of rock decomposition during diamond core drilling.Methods. Theoretical analysis, processing of the obtained experimental data.Findings. The decrease in power consumption of rock decomposition process during drilling with jet pulse flushing was studied. The influence of the bottom-hole power and jet pulse flushing parameters on the efficiency of rock decomposition process was investigated. Physical mechanisms of mining rock degradation under the jet pulse flushing were considered in the article.Originality. It was established that the drilling performance is growing along with increasing of pauses between the flushing liquid supply intervals. At that, the relative reduction of energy consumption of the rock decomposition process is increasing when the bottom-hole power is decreasing. The study provides theoretical grounds for the increase in the mechanical rate of drilling during the jet pulse flushing owing to utilization of the generated frictional thermal energy in the bottom-hole. It is demonstrated that using pulse flushing intensifies the processes of thermal cycling degradation of the mining rock. Practical implications.It is demonstrated that the pulse flushing mode has a potential to improve the performance of diamond core drilling. The outcomes of the research can be useful for grounding the specifications of the jet pulse flushing method during the development of the energy saving modes of diamond core drilling processes.
Purpose. To study the effect produced by the intermittent flushing on hydrodynamic processes in the hydraulic system of a diamond bit. Methods. Mathematical modeling methods and CFD experiment.Findings. A mathematical model of hydrodynamic processes in the flushing ports of the drill bit hydraulic system in conditions of drilling with intermittent flushing is presented. Numerical study of hydrodynamic processes for symmetric intermittent flushing was conducted. The velocity and pressure fields in the flow of the drilling fluid (water) in the ports were obtained. It was shown that pressure changes significantly in the flow with formation of low pressure zones and low intensity vortex during the pause in feeding. Analysis of the obtained effects shows that the use of intermittent flushing allows to control the hydrodynamic processes and influence the diamond drill bit operation.Originality. Hydrodynamics of intermittent flow of the flushing fluid in the hydraulic system of drill bits was investigated for the first time ever. The obtained results are the basis to theoretical substantiation of technological effects during drilling with intermittent flushing, such as improving bottom hole cleaning from slurry and increasing drilling speed. Practical implications.The results of the study are important for developing a technique and technology of diamond drilling with intermittent flushing.
Purpose. Development of calculation procedure and analysis of pressure losses in the flow of washing fluid circulating through a hydraulic system of the core barrel.Methods. Theoretical analysis based on the methods of hydraulic calculation.Findings. An approach to computation of hydraulics processes is proposed herein. Design ratios have been developed in order to determine the pressure losses in the inner area of the core barrel and in the annular space, taking into account changes of the hydraulic system geometry by height of the barrel. The regularities of pressure loss change in the flow depending on the depth of the discharge ports are obtained. The influence of the core bit's wear on pressure loss was studied. The efficiency of the hydraulic systems of core bits 01А3-76 and БС33-76 was analysed.Originality. It is proved that the existing recommendations for determining the pressure losses in the hydraulic system of the core barrel give conservative values of this parameter. The proposed method of determining the pressure losses, as distinct from the known, is sensitive to the design features of the barrel and core bits. For the in first time, the developed procedure takes into account pressure changes in the hydraulic system during the run due to the core bit wear. It is shown that the loss of pressure during the run can be used as an indicator of the core bits' wear.Practical implications. The proposed method allows to determine more precisely the necessary pump rate in developing borehole drilling technology. The suggested calculation procedure can be used to design the flushing system of new core bit concepts as well.
Представлены результаты производственных испытаний технологии оборудования гидрогеологической скважины криогенно-гравийным фильтром. Определена экономическая эффективность испытанной технологии.
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