Analysis Of Mechanical Properties Of Small Borehole Drilling Tool Connection Thread

In the reservoir development, slimhole drilling technology is widely used in the old well drilling. But in slimhole drilling, due to the old well hole production casing size limit and capacity constraints, pump and drill must have high strength, to improve the drilling depth, it is necessary to design a special drill pipe, in the case of decrease the size of cross section to improve the strength of the drill pipe. Because of the weakest part of a special drill pipe is the nipple, so you need to analysis this kind of slimhole drilling tools, to see if it is suitable for practical drilling condition.Based on the analysis of API standard NC31 clasp, the thesis put forward a new double shoulder special tool joint. In order to analyze the tool joint mechanical properties, the thesis build on refined 3 d mesh, then the three-dimensional finite element model is established. Through the analysis of the existing full well drill string dynamics simulation platform, the thesis studies the sidetrack drilling operation in the whole well drill pipe under load conditions, to provide basic data for the analysis of drill pipe joint thread strength. Then the three-dimensional finite element simulation analysis was carried out on the tool joint, the results of the analysis with API standard NC31 clasp tool joint finite element simulation analysis results are compared, and evaluated the mechanical properties of the tool joint. On this basis, analyzed the special 88.9 mm drill pipe joint of ultimate bearing capacity, including maximum and minimum torque under different tension torque, to guide the actual loading of the drill pipe and the stick to process, and get the limit of the drill pipe drilling depth. Finally, on the tool joint structure improvement, two-stage buckle joint structure is designed. And come with the structure's three-dimensional finite element simulation analysis, the analysis found that the improved joint mechanical's properties enhanced obviously,and is more suitable for the slimhole drilling.On the research purpose,the thesis based on the old heavy residual oil reservoir drilling,to increase drilling depth, improve recovery factor and so on in the reality needs, put forward the slimhole drilling tools special fastener structure; On the research methods, the research model based on 3 d finite element mesh refinement, simulated the stress characteristics of joint closer to actual working condition; In practical application, the study has important practical significance on determine the limit of slimhole drilling tools drill deep and guide the work of torque applied and clasp process.