1, Tubing classification
Tubing can be divided into the tubing (NU), upset tubing (EU) and the overall joint tubing. Flat means theoil casing pipe end without directly threading thicker and bring couplings. Upset tubing means after two pipe ends through external upset, then threading and bring couplings. Overall joint tubing means through internal upset end car thread the other end through the car outside the thick thread, with no direct connection couplings.

2, Tubing role
① extracting oil and gas: oil and gas well cementing kick and then placed in the oil casing pipe to extract the oil and gas to the surface.
② water: When the downhole pressure is not enough, through the tubing into the well water.
③ steam injection: in heavy oil thermal recovery process, the use of insulated tubing downhole steam input.
④ acidizing and fracturing: Late in drilling oil and gas wells or in order to improve the yield, it is necessary to enter the reservoir acidification and fracturing media or cured, and cured medium is delivered by pipeline.