Oil casingIt is mainly used for drilling oil and gas wells and transporting oil and gas. It includes oil drill pipe, oil pipe and oil pumping pipe. Oil drill pipes are mainly used to connect drill collars and drill bits to transmit drilling power. Oil casing is mainly used to support the borehole wall during and after the drilling process, so as to facilitate the normal operation of the whole oil well during the drilling process and after the completion. The oil casing mainly transports the oil and gas at the bottom of the oil well to the surface. Oil casing is the lifeline of oil well operation. Due to different geological conditions, the underground stress state is complex, and the tensile, compressive, bending and torsional stresses act on the pipe body, which puts forward higher requirements for the quality of the casing. Once the casing itself is damaged for some reason, the production of the whole well may be reduced or even scrapped.

According to the strength of the steel itself, the oil casing can be divided into different steel grades, namely J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. Different steel grades are used for different well conditions and well depths. In a corrosive environment, the housing itself is required to have corrosion resistance. In complex geological conditions, the casing is required to have the ability to resist collapse. 27MnCrV is a new type of steel for the production of TP110T oil pipe sleeve, and the conventional steel for the production of TP110T oil pipe sleeve is 29CrMo44 and 26CrMo4. Compared with the latter two, 27MnCrV contains less Mo, which can effectively reduce the production cost. However, after the production of 27MnCrV by conventional quenching process, there is obvious high temperature temper brittleness, resulting in low impact toughness and instability. There are usually two ways to solve such problems in production. One is to avoid high temperature brittleness, rapid cooling after tempering to obtain toughness. Secondly, the subcritical quenching method can effectively improve the harmful elements and impurities and improve the toughness through the incomplete austenitization of the steel. This method requires strict heat treatment equipment and requires additional costs. AC1 = 736,AC3 = 810, and the heating temperature during subcritical quenching is between 740 and 810. The heating temperature was 780 minutes and the quenching holding time was 15 minutes. The tempering temperature after quenching is 630, and the tempering heating holding time is 50 minutes. Since the subcritical quenching is heated in the two-phase region, the quenching is carried out in the state of retaining some undissolved ferrite, and the toughness is improved while maintaining a high degree. At the same time, the low temperature quenching is lower than the conventional temperature, which reduces the quenching stress, thereby reducing the quenching deformation, ensuring the smooth progress of heat treatment production, and providing good raw materials for subsequent turning processing. The process has been applied in processing plants. The quality data show that the yield strength Rt0.6, tensile strength Rm 910-940MPa and impact toughness Akv 65-85J of the steel pipe after heat treatment meet the requirements of damage resistance.

The data show that the 27MnCrV steel pipe is a kind of oil casing. On the other hand, it also shows that the subcritical quenching process is a method to avoid high temperature brittleness in steel production. Oil casing is a kind of large diameter pipe, which can fix the well wall or borehole of oil and gas well. The casing is inserted into the borehole and fixed with cement, which helps to stratify the borehole and prevent the borehole from collapsing. At the same time, the drilling mud is circulated, which is convenient for drilling and production. Oil casing steel grades are: H40, J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. The processing forms of casing head are: short round thread, long round thread, trapezoidal thread, special buckle, etc. Used in oil well drilling, mainly used to support the well wall during drilling and after completion to ensure the normal operation of the entire oil well during drilling and after completion. The important position of oil pipelines The petroleum industry is an industry that uses a large number of tubing, and tubing occupies a very important position in the petroleum industry. The consumption of oil well pipe can be calculated according to the annual drilling footage. The mechanical and environmental behavior of oil pipelines has an important impact on the oil industry's adoption of technology and increased production and efficiency.