Casing string

• Casing string
  Casing string in oil and gas drilling projects, is the steel strings according to different uses and purposes well down.
  Its primary role for protection, sealing all kinds of complex formation, stability, setting up oil and gas channels, installation of wellhead equipment, etc.
  Casing is divided into: tubing (top), surface casing and intermediate casing, production casing (casing) and so on.
  Hanging from the top (outer) casing bottom, and does not extend to the top of the wellhead casing liner.
  China and international drilling casing series are usually 20 ", 13 three-eighths" 9 five-eighths ", 7" and 5 "(outer diameter of casing).