Oil casing application
Oil casing is a steel pipe used to support the wall of oil and gas Wells to ensure the normal operation of the drilling process and the entire well after completion. Each well uses several layers of casing depending on the drilling depth and geology. Casing after the well to use cement, it is different from tubing, drill pipe, can not be reused, belongs to a one-time consumption of materials. Therefore, casing consumption accounts for more than 70% of all oil well pipes.
Casing classification
Casing can be divided into pipe, surface casing, technical casing and oil casing according to the use.
According to the strength of the steel itself, the casing can be divided into different steel grades, namely J55, K55, N80, L80, C90, T95, P110, Q125, V150 and so on. Different well conditions, well depth, the use of steel grades are also different. In the corrosive environment, the casing itself is also required to have corrosion resistance. In the place of complex geological conditions, it is also required that the casing has the performance of anti-collapse.
Oil casing specifications and dimensions
1, domestic casing according to SY/T6194-96 regulations, casing length is variable, its range of 8-13m. However, casings not shorter than 6m May be supplied, and the number shall not exceed 20%.
2. The inner and outer surfaces of the casing shall not be folded, hairlines, separated layers, cracks, rolled folds and scars. These defects should be completely removed, and the removal depth should not exceed 12.5% of the nominal wall thickness.
3, the outer surface of the collar shall not have folding, hair lines, separation, cracks, rolling, scarring and other defects.
4, casing and collar thread surface should be smooth, no burr, tear and enough to interrupt the thread affect the strength and tight connection of other defects.
Oil casing standard
API SPEC 5CT-2011 Tubing and Casing Specification is a standard published by the American Petroleum Institute for petroleum casing, which is commonly used in petroleum tubing, tubing, and casing.