Production process flow of casing and tubing

Date:2024-04-22Tags:Casing, well casing, casing and tubing, API5CT

Casing and tubing are steel pipes used to support the well walls of oil and gas wells to ensure the normal operation of the entire oil well during the drilling process and after completion. Each well requires several layers of casing and tubing based on different drilling depths and geological conditions. Cement must be used to cement the casing and tubing after it is lowered into the well. Unlike oil pipes and drill pipes, it cannot be reused and is a one-time consumable material. Therefore, the consumption of casing accounts for more than 70% of all oil well pipes. Casing and tubing can be divided into: conduit, surface casing, technical casing and oil layer casing according to usage conditions. Casing and tubing is used to create a good flow channel for oil or natural gas in underground reservoirs to flow to the surface. The important function of production casing is to protect the well wall and isolate fluids in each layer, so as to facilitate layered testing, layered mining and layered transformation of oil and gas wells.

Casing and tubing

Production process of oil casing and tubing:

The pipes are inspected by the magnetic flux leakage detector, and the qualified products are processed by the CNC pipe thread lathe in turn. If they pass the inspection, they will be used for future use: the bad coupling materials are threaded by the CNC pipe thread lathe.


After the inspection, the flaw is detected by the magnetic flux leakage detector, and the pipe is marked after passing the inspection. Next, the coupling screwing machine connects the pipe to the coupling. After passing the inspection, the marking machine is used for marking, and the pressure is tested by the hydrostatic pressure tester (water pressure (0~70MPa, different pipe diameters and different pressures), measure the length and weigh, put protective rings on both ends of the pipe, use an automatic painting machine to evenly apply epoxy asphalt anti-corrosion paint on the outer wall of the pipe, then spray mark, and finally the finished product passes the inspection Then pack it and put it in the product storage area.


Casing and tubing process flow

Raw material preparation: The raw material of oil casing is mainly steel, usually carbon steel or alloy steel. Before production begins, steel plates or steel pipes of various specifications and quality grades need to be prepared as raw materials.


Plate cutting and forming: First, the prepared steel plate is cut into slabs of appropriate size according to the design requirements. Then, the slab is rolled into a tube shape by a plate rolling machine to form the initial shape of the oil casing.


Welding process: welding the rolled tubular steel plate. This step usually uses technologies such as high-frequency induction welding, arc welding or inert gas shielded welding to ensure that the welding quality meets standard requirements.


Heat treatment: After welding is completed, the oil casing needs to be heat treated to eliminate internal stress and improve the mechanical properties of the steel. Heat treatment includes annealing, normalizing, quenching and other processes. The appropriate heat treatment method is selected according to different steel materials and requirements.


Cold working and forming: The heat-treated oil casing needs to be cold worked and formed to achieve the size, shape and surface quality required by the design. This may involve cold drawing, cold rolling, cold bending and other processes.


Surface treatment: Surface treatment of oil casing is very important, usually including rust removal, pickling, shot blasting and other processes to ensure that the surface of the pipe is smooth and clean, and to improve corrosion resistance.


Inspection and quality control: During the production process, various inspections are required on oil and casing, including dimensional inspection, chemical composition analysis, mechanical property testing, etc., to ensure that product quality meets the standard requirements of  API5CT. At the same time, a complete quality control system is established to strictly control every link.


Performance: Solution to poor toughness of casing and tubing

One is to use rapid cooling after tempering to avoid high temperature brittleness and gain toughness.


The second is the sub-temperature quenching method, which effectively improves harmful elements and impurities and improves toughness through incomplete austenitization of steel. The first method has relatively strict requirements on heat treatment equipment and requires additional costs. The low-temperature fire is lower than the conventional temperature, which reduces the quenching stress and thereby reduces the quenching deformation. This ensures the smooth operation of heat treatment production and provides good raw materials for subsequent wire processing.

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