Seamless carbon steel pipe - oil casing

Oil casing seamless carbon steel pipe is a kind of pipe specially used for oil well pipe system, the main function is to protect the well wall formed in the drilling process, isolate different strata and prevent underground media from penetrating into the wellbore, its design and manufacture must strictly meet the high pressure, high temperature and corrosion environment requirements of oil field engineering. The following details the concept of this product, manufacturing process, performance characteristics and applications.

What is oil casing seamless carbon steel pipe?

Oil casing seamless carbon steel pipe is made of low carbon steel through perforation, drawing or hot rolled seamless process, used in oil well casing. Casing is mainly used to protect the wellbore wall formed during drilling, isolate different formations, and prevent downhole fluids from contacting the formation directly, thereby improving the safety and production efficiency of the well.

Manufacturing process

The method of seamless manufacturing is used, and the common perforation method and drawing process are used. Compared with welded pipes, seamless pipes do not have welded joints, have better uniformity and pressure resistance, and can maintain performance in high temperature and high pressure environments, which is suitable for use in oil fields.
After a series of drawing processes, casings often need to be annealed or normalized to improve the internal structure of the material, eliminate residual stress, and further improve toughness and fatigue resistance.
After production, it is usually subjected to internal and external anti-corrosion coating treatment (such as spraying epoxy or 3PE/3PP coating) and cathodic protection to cope with the corrosion of groundwater, hydrogen sulfide, carbon dioxide and other media.

Product standard

Oil casing is often referred to API 5CT standard, which specifies the chemical composition, mechanical properties, dimensional tolerances, inspection methods and test requirements of oil well casing. API 5CT is divided into different grades (such as Grade E, Grade J, Grade K, Grade L, etc.), and different grades correspond to different performance and use environments.

Material requirement

Oil casing seamless carbon steel pipe is usually made of low carbon or low alloy steel, this kind of steel usually has good weldability, ductility and sufficient strength.
In addition, it is also necessary to strictly control the content of carbon, manganese, silicon, phosphorus, sulfur and other elements to ensure that no embrittlement or rapid corrosion occurs under high pressure, high temperature and corrosive media environments. At the same time, according to different grades (such as J55, K55, etc.), the chemical composition and mechanical performance requirements will be different.

Parameter requirement

Outer diameter: 10 mm -910 mm.
Wall thickness: 1 mm -56 mm.
Length: 4.88m-14m or on request.

Performance characteristics

High pressure resistance and integrity
The seamless process is used to ensure that the pipeline structure is uniform, has good pressure resistance and impact resistance, and can run stably in high pressure environment for a long time.

Excellent mechanical properties
After proper heat treatment, the casing steel has high tensile strength and good ductility, which can meet the complex stress requirements in drilling, water injection and production.

Good corrosion resistance
Combined with internal and external anti-corrosion coating and cathodic protection technology, it can effectively resist corrosion in the environment containing hydrogen sulfide, carbon dioxide and other corrosive media, and extend the service life.

High dimensional accuracy
Strict manufacturing and processing technology ensures that the outer diameter, inner diameter and wall thickness of the pipe are uniform, ensuring the sealing and connection stability after installation.

Summary

The seamless carbon steel pipe has become the key component of oil casing system by its integrity without welds, strict heat treatment and precision machining technology, and comprehensive anti-corrosion protection measures. It can not only effectively protect the drilling wall, isolate the formation and transport media, but also show excellent mechanical properties and durability in high pressure and corrosive environments, providing a solid safety guarantee for oilfield production.