Turbine Blade Research Of Small Size Turbodrill Apply To Coiled Tubing

In recent years, along with the coiled tubing technology matures, it gets attention as a high efficient, low cost drilling technology. Domestic and foreign literature showed that use of coiled tubing in underbalanced drilling, smile hole drilling, deepening old wells, sidetracking and workover has a broad prospect.The coiled tubing operations process can’t lack downhole motor. At present, most of the coiled tubing operation is matching the screw drill. However, it has transverse vibration in the course of drilling, which has an adverse effect on the coiled tubing string life. And it has poor resistance to high temperature that is not suitable for deep well operation. Abroad has also been actively exploring turbodrill match coiled tubing to fit in request of the small drill press, low-torque limitations and improve ROP. Compared with the screw drill, all the components of turbodrill are made of metal, determines that it can withstand high temperatures, high pressure working environment. Now with the shallow oil and gas resource gradually dried up, toward the deeper formation drilling is the future trend of drilling work, as well as the development of coiled tubing technology, which the advantage will gradually emerge that the turbodrill match with coiled tubing.There was no small size turbodrill is especially suitable for coiled tubing operations at home, and some small size turbodrill has also existed the problem of low efficiency. The main research work of this paper is carrying out study of the blade design for small size turbodrill that can match with coiled tubing. Designing a small size, high efficiency plane cascade can satisfy the use of coiled tubing, on this basis attempt to use three dimensional (quasi-3D) turbine cascade design, improve the efficiency of turbodrill, and analyze the impact of turbine blade’s leading edge and trailing edge radius to turbine efficiency.Firstly, according to some requirements of the coiled tubing drilling, and referring to parameters of foreign same specifications turbodrill decided to structure and performance parameters that design of the turbine. On the basis of reference literature, comprehensive comparison of existing methods that create turbine cascade, selecting five polynomial method make the blade profile. In the course of selecting blade structure parameters, the effects of some structural parameters on hydraulic performance of turbine are analyzed, and preliminarily selected structural parameters blades. With the help of mathematical software MATLAB to solve the profile of turbine blade equation, then created3D model by solidworks, combined with fluid simulation analysis software FLUENT analyze the hydraulic performance of the model. The parameters of the structure of the blade can be preferably optimized and adjusted to obtain a high efficiency blade according to the results of the analysis.The main contents and conclusions are completed and obtained in this paper:1. Determined turbine blade structure angle by theoretical calculation formulas according to the performance and structure parameters of turbine;2. To determine the turbine blade installation angle, the leading edge of circular arc radius, the trailing edge of circular arc radius, the leading edge of the cone angle, the trailing edge of the cone angle, relative pitch according to the existing empirical formulas and the range of experience values. Some of the parameters may need to be modified according to the hydraulic simulation calculation results;3. Chosen quintic polynomial as a design method that type line of the turbine blade section, and in accordance with the parameters determined by the turbine blades using matlab to solve the suction and pressure side cross-sectional profile equation. Finally, created the3-D model for turbine stator and rotor using solidworks according the blade section profile equation;4. Constructed the fluent channel model of turbine stator and rotor, and imported it into numerical fluid analysis software fluent, the hydraulic performance of turbine are simulated to select the appropriate parameters. Under the premise of meeting performance, try to improve the hydraulic efficiency of the turbine as far as possible. To calculate the mechanical properties data of turbine that has24blades-Torque T, input power N1, output power N2, pressure drop△P and efficiency η, and drew the corresponding performance parameters change curve with speed n. According to the hydraulic simulation data and the initial design parameters, when the displacement is121/s, meet the design requirements of the single-stage turbine rated speed is1900r/min, the pressure drop is about0.119MPa, torque4.47N, maximum efficiency is about62.27%;5. Changes of turbine blade leading edge radius impact on the turbine performance are simulated and analyzed. It can be seen from the calculation results and the curve is done by the results, when the other conditions remain unchanged with the leading edge radius increases the turbine torque, pressure drop, the output/input power are showing an increasing trend. But the input power of the growth rate slightly faster than the output power, efficiency show a downward trend. Leading edge radius is in the range of0.6～1.1mm, the percentage change of turbine efficiency is relatively small, no more than1%.6. Changes of turbine blade trailing edge radius impact on the turbine performance are simulated and analyzed. It can be seen from the calculation results and the curve is done by the results within the permissible range of trailing edge radius, if the other conditions remain unchanged with the trailing edge radius increases the turbine torque, pressure drop, the output/input power are showing an increasing trend. But the power output growth faster than input power, efficiency shows a downward trend, and declined rapidly. Trailing edge radius is in the range of0.4-0.6mm. If the trailing edge radius increases0.1mm, the percentage change of turbine efficiency is larger relative to leading edge radius. In this respect, the trailing edge radius is larger than the leading edge radius.7. Try to take5different sections in blade, and obtain5sections profile at the same speed, the same output torque conditions. Then, between the sections is connected linearly along the line that is constructed by the center of the leading edge radius. According to the blade create turbine, it can be seen by hydraulic simulation calculation and analysis data in the case of meeting the initial design parameters, the highest efficiency of the turbine is about62.71%, the displacement is121/s, the speed is about1800r/min, the pressure drop is about0.113Mpa. The three-dimensional blade compared with straight blade, turbine performance have slight increase under the same displacement and turbine performance parameters meet the requirements, but it is not obvious. On the other hand, if the appropriate transition method can be found between the sections in the future, it will provide a great help to improving the hydraulic efficiency, it is worth being researched.