Oil and Gas Drilling, Different type of casing and their function

Different type of casing and their function :
Stope pipe:

1. It is run to prevent washout of near surface unconsolidated formation
2. It provides a circulation system for the drilling mud.
3. It ensure the stability of ground surface.

Conductor pipe:

1. It is run from the surface to a shallow depth to protect near surface unconsolidated formation.
2. Seal off shallow water Zones
3. It provide protection against shallow gas flow.

Surface casing:

1. It is run to prevent caving of weak formation that are encountered at shallow depth.
2. It should be set in competent rocks such as hard limestone.
3. It serves to provide protection against shallow blowout, hence BOPs are connected to the top of this string.

Intermediate casing:

1. It is usually set in the transition zone below or above an over pressured zone.
2. It seal off a severe loss zone or to protect against problem formation.

Production casing:

1. It is run to Isolate producing zone.
2. It provide reservoir fluid control.
3. It permits selective production in multizone production.

Liners:

1. It does not reach the surface.
2. Liners are hung on the intermediate casing by use of a liner hanger.