The
casing is mainly used to support the wellbore during and after drilling to ensure the normal operation of the entire oil well after the drilling process is completed. Different types of casing used in oil production: The surface oil casing is used to protect the well from contamination by shallow water and shallow gas layers and to support the wellhead equipment and maintain the other layers of the casing. Technical casing is used to separate the pressures at different levels so that the drilling fluid can be circulated and the production casing can be protected.
In order to install anti-blasting devices, leak-proof devices and tail pipes in wells. Oil reservoir casing drains oil and natural gas from the reservoir beneath the surface and is used to protect the well and stratify the drilling mud. When the oil casing is produced, the outer diameter is usually 114.3 mm to 508 mm. Domestic casing according to SY/T 6194-96 regulations, casing length is not fixed, its range of 8-13m. But no less than 6m can be provided, the number of which must not exceed 20%.
The inner and outer surfaces of the sleeve must not have folds, hair lines, separations, cracks, folds, and scabs. These defects should be completely removed, and the depth of removal should not exceed 12.5% of the nominal wall thickness.
Couplings shall not have defects such as folds, hairline, separation, cracks, pleats, and scabs on the outer surface of the coupling. The surface of the threads of the casing and coupling should be smooth. No burrs, tears, and enough breakage of the threads will affect the strength and other defects of the tight connection.
