| Trenchless or horizontal directional drilling technology in hard rocks is one of the most important factors to measure the level of trenchless drilling technology in a country. It is the driving force to promote the development of horizontal directional drilling technology forward with good application value and social benefits. The development of horizontal hard rock directional drilling technology requires not only theoretical innovation and craft merit but also need to further implement of creating device. At present, the conventional directional drilling technique is mainly rotary drilling hard rock and special reamer. While drilling in hard, broken, soft interlayer and gravel layer, it is unavoidable to face many problems such as difficult construction, low drilling efficiency and high cost. Traditional hard rock complex stratum horizontal directional drilling technology and equipment have new hard rock horizontal directional drilling process equipment an urgent thing. All the well-known research institutions, universities and technical services companies are actively involved in the research of the technology domestically and overseas with the aims to promote the technology of hard rock horizontal directional drilling.The hydraulic impact rotary drilling technology has unique advantages such as high drilling efficiency in hard rock stratum, good pore forming quality and less drilling accidents which is widely used in geological exploration, water well cores, oil drilling, geothermal drilling and scientific drilling fields. The hydraulic hammer drilling tool(The hydraulic jet hammer)as a kind of new type hammer which is using bi-stable fluidic amplifier as control mechanism, its energy utilization rate is high and the working conditions of the drilling tools are well adapted, which have a good application prospect of new type hydraulic hammer drilling tools. Using together with screw motor drilling tools can effectively solve the difficulties of long construction period drilling in hard rock, low drilling efficiency and higher costs in the fields of oil drilling and gas well drilling and horizontal directional drilling.The paper aimed at the problems of horizontal directional drilling technology in hard strata, the hydraulic hammer drilling tool equipped with the screw motor is put forward applying in the field of hard rock horizontal directional drilling for the first time, the hydraulic hammer drilling tool is developed with large impact energy, long service life and high working stability which is used in horizontal directional drilling. Analyzing the working principle of the impact drilling tool and theoretical research of pressure changing rules of front and back cavity in the cylinder body, the GSC- 203 hydraulic hammer drilling tool is designed which is used in hard rock horizontal directional drilling, the numerical simulation calculation of the flow field and pressure distribution inside the drill tool are completing, the simulation results and the experimental results is analyzing contrastively, and the working performance of the GSC- 203 hydraulic hammer drilling tool is evaluated synthetically which is used in horizontal hard rock directional drilling. The main research contents and conclusions of this paper are as follows:(1) For the problems exist in the technique of horizontal directional well such as low drilling efficiency and long construction period and high drilling cost, the research status and advances on the domestic and overseas technology equipment and methods for conventional hard rock drilling are researched, the working mechanism and application advantages of the hydraulic hammer drilling tool in the field of horizontal directional well, and the feasibility research of the development of the hydraulic hammer drilling tool used for hard rock horizontal directional drill. For the structure optimization design and promotion and application of sinker drill tool, a preliminary basis is provided.(2) The theoretical research of the liquid jet oscillation drilling tool in the field of hard rock horizontal directional drilling is carried out based on the basic knowledge of fluid dynamics, the mathematical models of pressure variations in front cavity and back cavity and the horizontal motion of piston impact hammer in the process of hydraulic hammer drillinging for hard rock horizontal directional drill are set up, which provide the theoretical basis for structural design.(3) The structure design, drawing and prototype of GSC-203 hydraulic hammer for hard rock horizontal directional drill are completed according to the construction technique requests, the structural strength of drilling tool is checked, and the theoretical calculations on the service life of element, loading capacity of seal grooves and the matching capability between impact drill tool and roller bit are carried out to provide technical support for performance optimization of impact drilling tool.(4) The model of fluid filed inside of impact drilling tool was established with the help of three-dimensional mapping software and mesh tool such as Solidworks and Hypermesh, and the flow field and pressure distribution dynamic change rules of GSC-203 hydraulic hammer drilling tool system for hard rock horizontal directional drill were analyzed through the fluid dynamics numerical simulation analysis software FLUENT by dynamic meshing analysis technology, thus the rationality of structure design of impact drilling tool is verified. The simulated result shows that the final speed of hammer, system pressure drop and working frequency are affected by the work flow and the impact of travel. The longer the impact of travel, the faster the final speed of hammer and the lower the working frequency of drilling tool. And the system pressure increases with the increase of work flow and impact of travel.(5) Carried out the indoor experiment of GSC-203 type horizontal directional drilling with jet hydraulic percussive drill and designed the non-contact last impacting velocity measuring system based on the eddy current displacement sensor. Tested the last impacting velocity, frequency, system pressure drop and impact energy et with different length, different work flow and compared the experimental and numerical simulation results. Indoor experimental results and numerical simulation results are very similar, which show that the impact of horizontal directional drilling fluid percussion drilling tool is mainly affected by flow rate and impact travel. With the increase of the flow rate, the wall switch of the fluidic element is more stable, which is beneficial to improve the working performance of the impact drilling tool.(6) Completed the drilling test of jet type hydraulic percussion drilling tool for GSC-203 horizontal directional drilling. In the process of experiment, impact drill tool and screw motor mechs well, pressure of drilling tool system is moderate and drilling process is stable. The highest drill rate is 29m/h, the average drilling rate is 21.52m/h. Compared with the conventional hard rock horizontal directional drilling technology, and the drilling speed is increased by more than 30%.(7) Indoor experiment and numerical simulation calculation results show that, the GSC-203 type horizontal directional drilling with liquid jet dynamic impact drilling tool is reasonablely designed and can meet the technical requirements of hard rock horizontal directional drilling to drilling tools, which is suitable for the hard complex formation of oil and gas pipeline laying, underground public facilities construction horizontal directional drilling construction fields. |
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