Definition - What does Casing String mean?
Casing String is a stretched section of an oilfield pipe which is lowered down in the wellbore and cemented in order to reach the hydrocarbons in the reservoir. This string is primarily used for further cementing of a well and helps in the isolation of the well from hydrocarbons when the drilling operation is not performed.
Petropedia explains Casing String
A Casing String has casing joints which are roughly 10 to 12 meters in length with a male threading on each end and is connected with small length couplings also known as female threaded pipes. The Casing String has to withstand the string load and thus, the strength of material required for Casing String has to be very high.
There are three types of casings used in the industry:
- Hole director
- Intermediate string
- Production string
Some of the important reasons because of which casing is required in a well are:
- Provisions of pressure integrity across the wellbore
- Protection of fresh groundwater from contamination
- Sealing off fractured locations in a well
- Sealing high pressure zones
- Sealing low strength formations