Casing is important to oil drilling equipment, and its main equipment includes drill, core pipe and casing, drill collars and drilling small diameter steel pipe and so on.

The casing is used to support oil and gas wall of the pipe, to ensure that the drilling and completion of the process of the normal operation of the wells. Depending on the drilling each well depth and geological conditions, to use several layers of casing. Casing cementing go down after using it with tubing, drill pipe are different, can not be reused, a one-time consumable materials. Therefore, the total consumption of the casing is 70% of the oil well pipe. Casing can be divided according to usage: catheter, surface casing, casing and production casing. Casing is a large-diameter pipe, play a fixed oil and gas wells, or wellbore wall effect. The casing is inserted into the well hole, fixed with cement to prevent the formation and borehole spaced borehole collapse and to ensure circulation of the drilling mud to the drilling mined.

Casing is mainly used for drilling oil wells during drilling and after completion of the support wall to ensure that the conduct of the drilling process and completion of the wells after the regular oil casing normal operation. OCTG mainly used for oil and gas well drilling and oil and gas transportation. It includes oil drilling pipe, oil casing, pump tubing. Oil drill pipes are mainly used to connect the drill collar and drill and pass drilling power. Casing is mainly used for drilling and completion of the right wall of the support, to ensure that the conduct and completion of the drilling process after the normal operation of the wells. Pumping wells at the bottom of the tubing will mainly oil, gas transported to the ground. Casing is to maintain the wells run lifeline. As different geological conditions, underground complex stress state, pulling, pressing, bending, torsional stress acting on the combined effect of the tube, which the casing itself, the quality of the higher requirements. Once the casing itself is damaged for some reason, could lead to the whole production wells, or even scrapped.