Different type of casing and their function :
Stope pipe:
- It is run to prevent washout of near surface unconsolidated formation
- It provides a circulation system for the drilling mud.
- It ensure the stability of ground surface.
Conductor pipe:
- It is run from the surface to a shallow depth to protect near surface unconsolidated formation.
- Seal off shallow water Zones
- It provide protection against shallow gas flow.
Surface casing:
- It is run to prevent caving of weak formation that are encountered at shallow depth.
- It should be set in competent rocks such as hard limestone.
- It serves to provide protection against shallow blowout, hence BOPs are connected to the top of this string.
Intermediate casing:
- It is usually set in the transition zone below or above an over pressured zone.
- It seal off a severe loss zone or to protect against problem formation.
Production casing:
- It is run to Isolate producing zone.
- It provide reservoir fluid control.
- It permits selective production in multizone production.
Liners:
- It does not reach the surface.
- Liners are hung on the intermediate casing by use of a liner hanger.
