Pipes used for oil recovery, gas recovery, water injection and acid fracturing are tubings.
The tubing is divided into plain end tubing(NU), external upset tubing (EU) and integral joint tubing. Flat tubing means that the pipe ends are threaded directly without thickening and have a coupling. The thickened tubing means that after both ends of tubing are thickened outside, threaded again, and then put on the coupling. The integral joint tubing refers to one end of the internal thickening with the external threads, the other end of the external thickening with the internal threads, direct connection without coupling.
The tubing has the following functions,
1. Oil and gas extraction: After the oil and gas well is completed and cementing, the tubing is placed in the casing to extract the oil and gas to the ground.
2. Water flooding: When the downhole pressure is not enough, pour water into the well through the tubing.
3. Steam injection: In the process of thermal recovery of heavy oil, heat pipes should be used to feed steam into the well.
4. Acidizing and fracturing: In the late drilling period or in order to increase the production of oil and gas wells, it is necessary to import acidizing and fracturing media or solidified materials into the reservoir. The media and solidified materials are transported through tubing.
Table 1 Common specifications of tubing