What is the manufacturing process of drill pipe?

Drill pipe is a hollow thick-walled steel pipe used for drilling. It can transmit vertical force and torque. It is widely used in various types of oil drilling, such as directional wells, horizontal wells, etc. The lower part of the drill collar is connected to the drill bit, and the upper part is connected to the drill pipe. The drill pipe mainly transmits motion and power, and the drill collar directly drives the drill bit to work.

1. Development of oil drill pipe

The history of humans using Gongxian drilling to obtain resources can be traced back to the 11th century. At that time, people used bamboo and wood as tools and people and animals as power to drill salt wells, and used the natural gas produced to boil brine to obtain table salt. These bamboo woods, which were first used for drilling wells, can be called the first generation of drill pipes. At the beginning of the 20th century, steel tools and equipment were used, and steam engines were used as power to drill wells. The drilling tools at that time can be regarded as the second generation of drill pipes. Due to the application of drilling technologies such as horizontal wells, deep wells, ultra-deep wells, and extended reach wells, drilling costs and drilling risks are also increasing. Traditional drill pipes can no longer meet the requirements of use. New drill pipes are moving towards high strength, high toughness, Development in intelligence, digitization, anti-corrosion, safety and environmental protection.

2.What are the manufacturers of drill pipes?

The world's famous drill pipe manufacturers include the U.S. Grant Drilling Tool Company (now acquired by National Oilwell Company) and the French-German joint venture Vaam Company, with two production capacities accounting for about half of the world's total. Representative drill pipe manufacturers in China include Shanghai Baosteel, Jiangsu Shuguang Grant Drill Pipe Co., Ltd., BAOWI STEEL MANUFACTURING CO., LTD, etc. In recent years, with the increase in oil prices, the usage and price of drill pipes have also increased. Shanxi Fengfan Drilling Tools Co., Ltd., Wuxi Simles Petroleum Special Pipe Manufacturing Co., Ltd., Shanghai Huashi Hailong Petroleum Equipment Co., Ltd., Jiangyin DeMaster Group and others have also joined the ranks of drill pipe production. Ordinary drill pipes have completely replaced imports and have formed a certain export capability.

3.The production of drill pipe roughly includes three parts: pipe end thickening, tool joint processing, friction butt welding and subsequent processing.

3.1Pipe end thickening

The pipe body material of oil drill pipe is low carbon alloy steel. The continuously cast and rolled round steel billet is heated by a large rotary furnace and then enters the stretching machine and the mandrel automatic punching machine for shaping. After being heated again, the inner and outer diameters are finished and straightened into the pier. Forging process. Since the welding part of the oil drill pipe is the weakest link during use, the ends of the seamless steel pipe must be thickened at both ends of the pipe body before welding to increase the thickness to improve the strength of the weak part and make the welding part The overall strength is greater than the overall strength of the pipe body. According to different pipe diameters, it is generally divided into three types: internal and external thickening, internal thickening, and external thickening, among which the internal and external thickening types are the main ones. The process of pipe end thickening is to first heat and evenly heat the pipe end of the seamless steel pipe; secondly, the pipe end is pierced using hydraulic or pneumatic methods. The outer surface is formed by a mold, and the inner surface is naturally formed by the temperature gradient: Finally, the entire pipe body is heat treated, straightened, and non-destructively inspected. The key technology for thickening the pipe end lies in the formation of the inner surface transition zone, because this part is the weakest and has the most complex stress during use. About 70% of accidents occur in this part, so it is very important to the quality of the drill pipe.

3.2Tool joint processing

The material of the tool joint is generally medium carbon alloy steel. The blank is heated and stamped in three times, and then machined after normalizing. First, the inner hole, outer circle, and end face of the blank are turned. Secondly, the joints are quenched and tempered to obtain comprehensive mechanical properties. Finally, the joints are threaded. The threaded parts must be copper plated or phosphated to prevent Sticking phenomenon occurs during use.

The quality of joints lies in the two key processes of heat treatment and thread processing. The heat treatment structure directly affects the various mechanical properties of the joint, so advanced drill pipe factories use fully automatic continuous controllable atmosphere protection heating, oil or water-based quenching agent quenching, and reducing atmosphere protection during the joint heating process to ensure that the workpiece is not Oxidation, decarburization and carburization. After the joints are quenched and tempered, surface hardness testing and magnetic particle testing are performed one by one. Thread processing is performed after heat treatment. The drill pipe thread is a coarse tapered thread. In the connection process of the drill pipe, the thread plays a key role. Therefore, thread processing is mostly carried out using high-precision CNC machine tools. The thread pitch, pitch, taper, pitch and other parameters of the processed joints are measured one by one to ensure the thread buckle shape and accuracy requirements, thus effectively ensuring the quality of the drill pipe joint. Connection performance.

3.3Friction butt welding and subsequent processing

Friction butt welding of drill pipe is an important part of the entire drill pipe production. In order to ensure the welding quality, almost all drill pipe factories use fully automatic friction welding machines and are equipped with welding parameter monitoring devices to monitor the friction time during the welding process. , friction pressure, upsetting pressure, upsetting time and shortening amount and other parameters are automatically monitored and recorded to ensure weld quality. After welding, it is necessary to remove the welding fingernails, perform tempering treatment on the welding heat-affected zone, and conduct non-destructive inspection of the welds. Among them, the tempering heat treatment of the seams is very important. Almost all manufacturers use the medium heating method. Carry out and automatically record heating temperature, heating time, holding time, quenching time and other parameters. The advantages of this kind of weld heat treatment are: the heating heat-affected zone is narrow and the heating time is short; the structure of the welding zone is uniform and stable, and the performance is reliable; the residual stress on the surface of the welding zone is small.

4.Manufacturing Process of Drill Pipes

Drill pipes are crucial in the oil and gas industry, used for drilling deep wells. They must withstand high pressure, temperature, and wear during drilling operations. The manufacturing process for drill pipes involves several key stages to ensure strength, durability, and reliability.

4.1Material Selection

The manufacturing process begins with selecting high-quality steel alloys. The material must have excellent tensile strength, resistance to corrosion, and fatigue. Common materials used include carbon steel and alloy steel, often with additional elements like chromium and molybdenum to enhance performance.

4.2 Billet Preparation

The selected steel is formed into billets or blooms, which are large blocks or cylinders of metal. These billets are carefully inspected for impurities or defects before moving to the next step in the process.

4.3 Heating and Extrusion

The billets are heated in a furnace to temperatures between 1,600°F to 2,100°F (871°C to 1,149°C). This heating process makes the material malleable and ready for shaping. The billets are then extruded into hollow pipe shapes through rotary piercing and elongation. This process stretches the material into the desired length and diameter while maintaining uniform wall thickness.

4. 4 Rotary Piercing and Elongation

The billet is pierced by a rotating tool, creating a hole in the center of the material. The hollow pipe is then elongated and stretched to the required length using elongation mills. This ensures that the drill pipe is formed to the correct dimensions.

4.5Heat Treatment

Heat treatment is a crucial step to enhance the pipe’s mechanical properties. The drill pipe is heated to a high temperature, followed by a rapid quenching process to harden the material. The pipe is then tempered at lower temperatures to relieve internal stresses and improve toughness, ensuring it can handle the pressures and forces encountered during drilling.

4.6Threading and End Finishing

The ends of the drill pipe are machined to create high-precision threads for connecting the pipes to other drilling equipment, such as collars, bit subassemblies, and other pipe sections. The threading process must meet strict specifications to ensure a secure and leak-proof connection.

4.7 Inspection and Testing

Rigorous inspection and testing are performed to ensure the drill pipes meet industry standards. Non-destructive testing (NDT) methods, such as ultrasonic testing, magnetic particle inspection, and eddy current testing, are used to detect any internal or surface defects. Mechanical property tests, including tensile, impact, and hardness tests, are conducted to verify the pipe’s strength and durability.

4.8 Surface Treatment and Coating

The drill pipes are coated with protective layers to resist corrosion and wear. This can involve applying phosphate coatings, varnishes, or other protective finishes. The coating not only increases the pipe's longevity but also helps to prevent damage during handling and transportation.

4.9 Final Inspection and Packaging

Once the drill pipes pass all tests and quality checks, they undergo a final inspection to confirm the dimensions and quality. The pipes are then cleaned, labeled, and packaged for shipment to customers or field operations.

To sum up, as the difficulty of oil exploration and development continues to increase, higher requirements are put forward for the quality of drill pipes, and the development is diversified. The production of drill pipes in various countries has gone through more than ten years of R&D and trial production. The manufacturing technology has basically matured and has begun to independently develop new products. I believe that in the near future, oil drill pipe products will surely be among the best in the world.