Oil casing pipe uses in oil and gas wells

Oil casing is a steel pipe used to support the well wall of oil and gas wells to ensure that the drilling process is carried out and that the entire well operates properly after completion. Several layers of casing are used in each well depending on the drilling depth and geological conditions. The casing is cemented after the well is drilled, and unlike tubing and drill pipe, it is not reusable and is a one-time consumable material. Therefore, the consumption of casing accounts for more than 70% of all oil well tubing.

Oil special pipe is mainly used for drilling of oil and gas wells and transmission of oil and gas. It includes oil drilling pipe, oil casing and oil pumping pipe. Oil drill pipe is mainly used to connect drill collar and drill bit and transmit drilling power. Oil casing is mainly used to support the well wall during the drilling process and after completion to ensure the drilling process and the normal operation of the whole well after completion. The pumping tubing is mainly used to transport oil and gas from the bottom of the well to the surface.
Oil casing is the lifeline that keeps the well running. Due to the different geological conditions, the downhole stress state is complex, with tensile, compressive, bending and torsional stresses acting on the tubing body in an integrated manner, which places high demands on the quality of the casing itself. Once the casing itself is damaged for some reason, it may lead to production reduction of the whole well or even scrapping.
According to the strength of the steel itself, the casing can be divided into different steel grades, i.e. J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. Different well conditions and depths require different steel grades. In corrosive environments, the casing itself is required to have corrosion resistance. In places with complex geological conditions, the casing is also required to have anti-crushing properties.

27MnCrV is a new steel grade for the production of TP110T steel grade casing. 29CrMo44 and 26CrMo4 are the conventional steel grades for the production of TP110T steel grade casing. 27MnCrV contains less Mo elements than the latter two, which can greatly reduce the production cost. However, the normal austenitizing quenching process is used to produce 27MnCrV with significant high-temperature temper brittleness, resulting in low and unstable impact toughness.
To solve such problems are usually used in two ways: one is the use of tempering after rapid cooling method to avoid high-temperature brittleness, to obtain toughness. The second is the sub-temperature quenching method through the incomplete austenitization of steel to effectively improve the harmful elements and impurities, improve toughness. The first method, relatively strict requirements for heat treatment equipment, requires the addition of additional costs.
AC1=736°C and AC3=810°C for 27MnCrV steel, the heating temperature during sub-temperature quenching is selected between 740-810°C. Sub-temperature quenching selected heating temperature 780 ℃, quenching heating holding time of 15min; quenching and tempering selected temperature 630 ℃, tempering heating holding time of 50min. due to sub-temperature quenching in the α + γ two-phase zone heating, quenching in the retention of part of the undissolved ferrite state, while maintaining a higher strength, toughness is improved.
At the same time, low-temperature quenching is lower than the conventional temperature, reducing the stress of quenching, thus reducing the deformation of quenching, which ensures the smooth operation of the production of heat treatment, and provides a good raw material for the subsequent wire turning process.
The process has been applied in the processing plant, quality assurance data show that the yield strength Rt0.6 in 820-860MPa, tensile strength Rm in 910-940MPa, impact toughness Akv in 65-85J between the steel pipe after heat treatment, 100% of the destruction resistance qualified. The data show that 27MnCrV steel pipe has been quite high quality high steel grade petroleum casing, on the other hand, also shows that the sub-temperature quenching process is a way to avoid high temperature brittleness in the production of steel products.

1. Petroleum casing is a large diameter tubing that serves to hold the wall or well bore of oil and gas wells in place. The casing is inserted into the borehole and secured with cement to help isolate the borehole from rock formations and prevent collapse of the borehole, as well as to ensure the circulation of drilling mud for drilling and extraction.
2. Steel grade of oil casing: H40, J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. Casing end processing forms: short round thread, long round thread, partial trapezoidal thread, special buckle, etc. It is mainly used for oil well drilling to support the well wall during the drilling process and after the completion of the well to ensure the normal operation of the entire well after the completion of the well.
3. The important position of oil pipe
4. The petroleum industry is an industry that uses a large amount of petroleum tubing, and petroleum tubing occupies a very important position in the petroleum industry.
5. 1, oil tubing usage, spending a lot of money, saving money, cost reduction potential is huge. The consumption of oil well pipe can be projected by the annual drilling footage. According to the specific situation in China, roughly 62kg of oil tubing is needed for every 1m of drilling, including 48kg of casing, 10kg of tubing. 3kg of drill pipe and 0.5kg of drill collar.
6. the mechanical and environmental behavior of oil tubing has an important impact on the adoption of advanced technology and increased production and efficiency in the oil industry.
7. The failure loss of oil pipe is huge, and its safety, reliability and service life are of great importance to the oil industry.