Oil casingUse

　　Oil casingIt is a large-diameter pipe that plays the role of fixing the oil and gas well wall or borehole. The casing is inserted into the borehole and cemented in place to prevent the borehole from separating rocks and collapsing, and to ensure the circulation of mud for convenience and extraction. Oil casing is a steel pipe that supports the pipe wall of oil and gas wells, and ensures the normal operation of the whole well. Depending on the depth and geology, several layers of casing are used for each well. Casing wells shall be cemented. It is different from tubing and drill pipe and cannot be reused. It is a one-time consumer material. Therefore, the casing consumption accounts for more than 70% of the total consumption of oil well tubing.

　　Oil casingOil, natural gas and oil, natural gas transmission. It includes oil drill pipe, oil casing pipe and pumping unit pipe. The oil drill pipe connects the drill collar and the drill bit to transmit power. Oil casing and support to the well wall to ensure the normal operation of the whole well. Oil pumping pipes are used to transport oil and natural gas from the bottom of the well to the surface.

Oil casing is the lifeline of oil well operation. Due to the different geological conditions, the underground stress state is complex, and the comprehensive effect of the tension, compression, bending and torsion stress of the pipe body puts forward higher requirements on the quality of the casing itself. If the casing itself is damaged for any reason, it may lead to production reduction or even the abandonment of the whole well.

The casing can be divided into different steel grades according to the strength of the steel itself, namely J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. Oil casing steel grade: H40, J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. Processing form of casing end face: short round thread, long round thread, trapezoidal thread, special buckle, etc. and well wall support to ensure the normal operation of the entire well after the end.

Different well conditions, well depth, the use of steel grade is also different. The casing itself also requires corrosion resistance in corrosive environments. Casing also needs to be pressure resistant where geological conditions are complex. 27MnCrV is a new type of steel used in the production of TP110T steel pipe casing, and 29CrMo44 and 26CrMo4 are used in the conventional production of TP110T steel pipe casing. Compared with the latter two, the content of 27MnCrVmo element is less, which can greatly reduce the production cost. However, after the production of 27MnCrV by normal austenite quenching process, there is obvious high temperature tempering brittleness, resulting in low impact toughness and instability. In order to solve this kind of problem, two methods are usually used: one is to use rapid cooling after tempering to avoid high temperature brittleness and obtain toughness. Secondly, the sub-temperature quenching method can effectively improve the harmful elements and impurities and improve the toughness through the incomplete austenitization of the steel. The first method has strict requirements for heat treatment equipment, which adds additional costs.