Casing Pipe

Chemical Composition, Mass Fraction(%)

Note：If the wall thickness is less than 17.78mm, the molybdenum content of the C90-1 steel grade has no lower limit.

 Dimension Tolerances

Tensile and Hardness Requirements

Casing: Casing is a wide range pipe that serves as the structural retainer for the walls of oil and gas wells, or well bore. It is inserted into a well bore and cemented in place to protect both subsurface formations and the wellbore from collapsing,  to allow drilling fluid to circulate, and extraction to take place. 

used for lining the complete borehole which has been dug into the ground to procure oil. Similar to the drill pipe, the oil well casing pipe is also subjected to axial tension, therefore they are required to be made from high-quality strong steel material. OCTG casing is large diameter pipe which are held in place in the borehole using cement.
The diameters of OCTG casing pipe range from 4.5″ to 36″. The well-cemented pipe acts as the structural component of the well and offer hole integrity. They prevent the well from collapsing when the drilling process is on. Good quality, well cemented casing can stay in place for the whole life of the well.The oil well casing pipe are further divided into:

• Conductor Casing – Conductor casing is the first boundary between the surface and the subsurface. It helps prevention of well collapse; it keeps away the groundwater and most importantly provides structural support. Conductor casing is installed in the ground by either drilling it or hammering it down. They are available in sizes ranging from 18″ to 36″.

• Surface Casing – The purpose of Surface casing is primarily environmental and to ensure safety. It helps in separating the freshwater zones, offering protection from blowout and supporting the wellhead and blow out prevention (BOP) equipment. Therefore surface casings are required to maintain very high safety standards. They are responsible for supporting the next casing in line.  They may vary in size depending on their purpose, but the most common size of surface casing is 13 3/8”.
  Intermediate Casing: Intermediate casing is not always required in all types of oil and gas production. If used, they are placed between the surface and the production casing. They are available in sizes ranging from 13 3/8” to 16”.

• Production Casing – Production casing help provide structural integrity and pressure control of the hydrocarbon-bearing sections mainly during the production of oil.

• Production Liner – Production liners can be suspended from the production casing or one of the previous casings. They help in reducing the cost significantly as the liner is not required to run through the full depth of the well. Liners can be pre-perforated to help save time and cost.

The oil well casing is subject to high axial tension because of the external pressure received from the rocks surrounding it and the internal pressure during the oil extraction. A well-cemented casing can be very useful in the drilling process in several ways:

• The casing holds the drill string, preventing the unstable upper formation from caving in

• Helps the prevention of contamination of water well zones
  Provides an even internal bore for easy installation of the production equipment

• Helps prevention of the contamination of production zones

• Helps prevention of fluid (oil) loss

• Helps seal off the high-pressure zones from the surface of the earth

Standards and Technical Conditions for Supply:API Spec 5CT ISO13680

Steel Grade: H40、J55、K55、M65、L80-1、N80-1、N80Q、C90、P110、Q125