Coiled tubing is a single length of several kilometers and repeated bending, achieve multiple plastic deformation of the new oil pipe. Coiled tubing equipment and its operation is called "universal working machine" in the foreign countries such as the United States, Canada and other countries, it has become the oilfield coiled tubing operations essential oil equipment. Currently the longest continuous tubing is 9000m long, with respect to such special tubing manufacturing core technology is:
1, The chemical elements
Due to the harsh environment service, coiled tubing mechanical properties and corrosion resistance have high requirements, to optimize the design of the chemical composition of the material, it must also implement clean control the whole process of smelting, rolling, etc., to minimize inclusions and S, P and other harmful elements.
2, Processing
Since dislocation multiplication after other causes hardening and Bauschinger effect together, transform law tubular body strength to control.
3, Heat treatment
By tube heat treatment to achieve optimum control of microstructure and properties, especially high strength and high ductility and low residual stress.
4, Welding Technology
Low carbon and low alloy steel, currently used mainly HFW welding technology, need to study the optimum welding parameters (such as current, voltage, frequency, welding speed, forming angle, the pressing amount, etc.), research and seam weld heat treatment technology.
5, Butt
To achieve continuous production HFW pipe, it must first take a long sheet, the current sheet docking mainly TIG, MAG and plasma welding or the like. The method under study is friction stir welding method.
6, Pipe butt
Coiled tubing during use may cause local damage, injury or defect part must be cut away, and the tubes are connected by welding. The traditional method of docking ships by hand TIG welding, the welding quality is difficult to control, so that the current automatic welding technology.
7, New manufacturing technologies
As CVR technology, which uses continuous pipe of the same size tube and heated to 940 ℃ through online medium frequency induction by thermomechanical rolling, on the one hand to achieve seamless or HFW weld optimization, on the other hand to achieve variable wall thickness or adjustable. In addition, there are special stainless steel tube continuous laser welding technology.