Oil Special Pipe Processing Technology and Application

The oil special pipe is mainly used for drilling oil and gas wells and conveying oil and gas. It includes oil drill pipes, oil casing, and oil pipes. Oil drill pipes are mainly used to connect drill collars and drill bits and transmit drilling power. The oil casing is mainly used for supporting the well wall during and after drilling to ensure the drilling process. And the normal operation of the entire well after completion. The oil pipe mainly transports the oil and gas at the bottom of the oil well to the ground.

Oil casing pipe is the lifeline for maintaining oil well operations. Due to different geological conditions, the state of the downhole is complicated, and the combined action of tension, compression, bending and torsion stress acts on the pipe body, which puts high requirements on the quality of the casing itself. Once the casing itself is damaged for some reason, it may result in a reduction in production and even scrapping of the entire well.

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 and so on. The well conditions and well depth are different, and the steel grades used are also different. The casing itself is also required to have corrosion resistance in a corrosive environment. It is also required that the casing has anti-crushing properties in places with complicated geological conditions. 27MnCrV is a new type of steel for the production of TP110T steel grade oil pipe sleeves. The conventional production of TP110T steel grade oil pipe sets is 29CrMo44 and 26CrMo4. Compared with the latter two, 27MnCrV contains less Mo element, which can greatly reduce production costs.

27MnCrV steel has AC1=736°C, AC3=810°C, and the heating temperature during sub-temperature quenching is selected between 740-810°C. The sub-temperature quenching selects the heating temperature of 780 ° C, the quenching heating holding time is 15 min; the quenching and tempering selects the temperature of 630 ° C, and the tempering heating and holding time is 50 min. Due to sub-temperature quenching in α + γ two phases.The zone is heated and quenched while retaining a portion of the undissolved ferrite, and the toughness is improved while maintaining high strength.

After the production of 27MnCrV by normal austenitizing quenching process, there is obvious high temperature temper brittleness, resulting in low impact toughness and instability. The method of rapid cooling after tempering avoids high temperature brittleness and obtains toughness. Sub-temperature quenching method effectively improves harmful elements through incomplete austenitization of steel grades and impurities to improve toughness. The requirements for heat treatment equipment are relatively strict and additional costs are required. The low temperature quenching is lower than the conventional temperature, which reduces the quenching stress, thereby reducing the quenching deformation, thus ensuring the smooth operation of the heat treatment production, and providing a good raw material for the subsequent wire processing.