A unique welding technique for coiled tubing pipes for oil and gas enterprises of the Republic of Belarus is being developed by the Certification and Testing Center of the Department of Equipment and Technology of Welding Manufacture of the Belarusian-Russian University.
This welding technique has a number of advantages: it helps avoid performing drill string assembly and disassembly operations; it gives access to sidetracks of the well, which can significantly reduce the cost of repair and restoration work.
It should be noted that the welding of these materials is rather difficult due to strict specifications that welded joints must meet when used in an aggressive environment and subjected to large alternating stresses. So far, positive results have been obtained in welding coiled tubing pipes with a specified minimum tensile strength (SMTS): 552 N/mm², 607 N/mm², 669 N/mm², 758 N/mm², 793 N/mm².
The technique is based on the use of the welding material with large accumulated plastic strain before fracture. Due to the specific character of alloying, the strength of the weld subjected to alternating bending strain increases to 800 N/mm² with little or no loss in ductility.
This welding technique involves using special equipment and tooling to ensure that the heat affected zone is not heated above the recrystallization temperature of the base metal.
This technique will significantly simplify and improve the efficiency of operations inside the oil and gas well, as well as facilitate and accelerate round trip operations.