Tubing can be divided into flat tubing (NU), thickened tubing (EU) and integrated joint tubing.Flat tubing means the end of the tubing is threaded without being thickened and is fitted with a coupling.The thickened tubing means that after the two ends of the tubing are thickened externally, they are threaded and coupled with a coupling.The whole joint tubing means that one end is internally thickened before externally threaded and the other end is externally thickened before internally threaded, which is directly connected without a coupling.
Usages of tubing:
1.oil and gas extraction: after the oil and gas well has been completed and cemented, the tubing is placed in the casing of the oil layer to pump oil and gas to the surface.
2.Water injection: when the downhole pressure is not enough, inject water into the well through the tubing.
3.Steam injection: In the process of heavy oil thermal recovery, heat insulation tubing should be used to input steam underground.
4.Acidizing and fracturing: to increase the production of oil and gas wells at the later stage of well drilling or in the future, it is necessary to input acidizing and fracturing media or solidified substances into the oil and gas reservoirs. Both media and solidified substances are transported through tubing.
|Specifications of Commomly Used API 5CT Tubing|
Steel grades of tubing:
Steel grades of tubing are: H40, J55 and N80, L80, C90, T95, P110. N80 is divided into N80Q and N80-1, similarities of the two are the tensile properties,differences are the delivery status and impact performance, according to the state of normalizing delivery or N80-1 when the Ar3 finishing temperature is greater than the critical temperature and tension after reducing air cooling.It can also be replaced by hot rolling, and neither impact work nor non-destructive testing is required :N80Q must undergo tempering (quenching and tempering) heat treatment, impact work should comply with API 5CT regulations, and non-destructive testing should be conducted.
L80 is divided into L80-1, L80-9CR and L80-13CR, and their mechanical properties and delivery state are the same. The difference is in usage, production difficulty and price. L80-1 is a common type, L80-9CR and L80-13CR are both highly corrosion-resistant tubing, which is difficult to produce and expensive, and is usually used in heavily corrosion-resistant oil wells.
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