Introduction Of Seamless Steel Pipe Petroleum Casing

Seamless steel pipe is widely used in our daily life, and one of the very important application areas is as our energy channel to transmit energy, including oil, natural gas and so on. It can be laid not only on land but also in the seabed, which brings great convenience to the energy circulation in different regions, and is a mode of transportation incomparable to land and sea transportation.

As such an important means of production of oil transportation pipeline, what is special? Here we come together to understand the seamless steel pipe in the oil casing knowledge.

Petroleum casing is the lifeline to maintain the operation of oil wells, mainly used to support the oil and gas well walls to ensure that the drilling process is carried out and the normal operation of the entire well after the completion of the well.

Oil pipe and casing is different from ordinary seamless steel pipe, due to the application of more complex geological environment, different geological conditions, the downhole stress state is complex, tensile, compressive, bending, torsion stress combined effect on the tubing body, the casing itself puts forward high quality requirements.

In API SPEC 5CT standard, the steel grade of casing and tubing indicates its yield strength and some special characteristics. The steel grade is usually indicated by one letter and two or three numbers, e.g. N80.

In most cases, the further back in the alphabetical order of the letters, the greater the yield strength of the tube is represented. For example, N80 Grade 1 steel has a greater yield strength than J55. The numerical notation is determined by the minimum yield strength of the pipe expressed in thousands of pounds per square inch. For example, the minimum yield strength of the N80 grade is 80,000lb/in2. The API SPEC 5CT standard lists the following casing grades: H40, J55, K55, N80, M65, L80, C90, C95, T59, P110, and Q125; and casing grades: H40, J55, N80, L80, C90, T59, and P110. The casing steel grades are H40, J55, N80, L80, C90, T59, P110.

Several layers of casing are used for each well according to different drilling depths and geological conditions. Cement is used to cement the casing after it is lowered into the well, which is different from tubing and drill pipe, not reusable and belongs to disposable consumable materials. Once the casing itself is damaged for some reason, it may lead to the reduction of production of the whole well, or even scrapped. Therefore, the consumption of casing accounts for more than 70% of all oil well tubing.