Introduction to seamless steel pipe oil casing

Seamless pipes are widely used in our daily lives. One of the very important application areas is as an energy channel for us to transmit energy, including oil, natural gas, etc. It can be laid not only on land, but also on the seabed, which brings great convenience to the flow of energy in different regions. It is a transportation method that is unmatched by land and sea transportation.

As such an important means of production, what is so special about oil pipelines? Let's take a look at the knowledge of seamless steel pipes in oil casing pipe.

Oil casing is the lifeline to maintain the operation of oil wells. It is mainly used to support the well wall of oil and gas wells to ensure the drilling process and the normal operation of the entire well after completion.

Oil pipes and casing are different from ordinary seamless steel pipes. Due to the complex geological environment and different geological conditions, the downhole stress state is complex. The combined effects of tension, compression, bending and torsion stress on the oil pipe body and casing itself have raised many questions. High quality requirements.

In the API SPEC 5CT standard, the steel grade of casing and tubing indicates its yield strength and some special properties. The steel grade is usually represented by a letter and two or three numbers, for example: N80.

In most cases, the letters later in the alphabetical order represent a greater yield strength of the pipe. For example, N80 Grade 1 steel has a higher yield strength than J55. The numerical sign is determined by the minimum yield strength of the pipe, expressed in thousands of pounds per square inch. For example, the N80 grade has a minimum yield strength of 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; casing grades: H40, J55, N80, L80, C90, T59 and P110. Casing steel grades include H40, J55, N80, L80, C90, T59, and P110.

Each well uses multiple layers of casing according to different drilling depths and geological conditions. Cement is a material used for cementing wells after casing is lowered into the well. Unlike oil pipes and drill pipes, cement cannot be reused and is a one-time consumable material. Once the casing itself is damaged for some reason, the well production may be reduced or even scrapped. Therefore, the consumption of casing accounts for more than 70% of all oil well tubing.

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