Requirements for the Quality of Oil Casing Couplings

What is an oil casing coupling?

Oil casing coupling is a kind of oilfield drilling tool, mainly used for the connection of oil pipes. The oil casing coupling mainly solves the problem that the existing coupling is prone to fatigue and fracture due to stress concentration.

The coupling structure of the oil casing is: the end of the oil pipe and the inner wall of the coupling are connected by a tapered thread, and the end of the coupling body and the oil pipe are connected by a flat thread with the same thread and the same pitch. It has the characteristics of stress concentration at the root of the external thread of the oil pipe connected with a single taper thread, which is not easy to cause fatigue and fracture, and has a good connection effect. Prevent the occurrence of oil well pipe string breakage accidents.

Requirements for the quality of oil casing couplings:

In order to increase the service life of the oil well pipe and reduce the cost, the oil field requires that the oil well pipe can be reused many times, which puts forward the requirements of excellent anti-galling performance for the oil pipe. Because if the tubing is hooked, the integrity of the threaded connection will be damaged. Continued use may lead to leakage at the threaded connection, reduction of the connection strength, and serious accidents such as falling off the well, causing huge economic losses to the oil field.

The API specification requires that the oil pipe can be made and unbuckled 6 times without sticking when in use. Although the well conditions of each oil field are different, the make-up conditions (make-up method, make-up torque and rotational speed control, etc.) when the tubing goes down the well are also different, and the requirements for the number of times of make-up and break-up of the tubing are different. All the above require that the number of times of making and unloading the oil pipe can reach more than 10 times, and some oil fields even require it to reach more than 30 times.

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