The seamless drill pipe for oil drilling is made by friction welding between the drill pipe body and the joint. On the basis of ensuring that the structure and mechanical properties of the drill pipe body and joints meet the technical requirements, the structure and mechanical properties of the friction welding weld and the heat-affected zone become the key to the quality control of the drill pipe.
The mechanical properties of friction welding seam and heat-affected zone are determined by its structure. Therefore, studying the microstructure characteristics of friction welding seam and heat-affected zone of drill pipes and their influence on mechanical properties is important for guaranteeing and improving drill pipes. Quality is of great significance.
Friction welding of drill pipe is a solid phase welding. Since then, people have carried out detailed studies on the structure of fusion welding welds and heat-affected zones, and have reached clear conclusions. However, there are few reports on the research on the structure of friction welding welds and heat-affected zones of drill pipes.
Features of drill pipe joints:
1.Increase the torsional strength of the joint.
2.The streamlined optimization design is adopted to increase the inner diameter of the joint, thereby reducing the cyclic pressure loss along the inner edge of the drilling tool, and at the same time reducing the joint outer diameter, thereby greatly improving the fishing ability of the drilling tool and correspondingly reducing the annulus circulating pressure loss. Improve the hydraulic performance of the joint and maintain high torsion resistance.
3.The smooth inner diameter joint design is adopted to obtain a more stable liquid flow and smaller turbulence, reducing erosion; reducing the chance of cement and solid particles depositing in the joint; improving the transmission efficiency and capacity of the pump in the drill string; Increased the ability of lifting and lowering various cable instruments in the drill string (reduce the possibility of impact)
4.The double shoulder design makes the stress distribution more balanced, and the load can be shared at both ends of the buckle; compared with the API connection, the rigidity is stronger, and the stress concentration at the connection is reduced; because the stress concentration is reduced, the resistance is improved Fatigue, thereby extending its service life.