Casing string

This article may be too technical for most readers to understand. Please help improve it to make it understandable to non-experts, without removing the technical details. (November 2020) (Learn how and when to remove this message)

In drilling technology, casing string is a long section of connected oilfield pipe that is lowered into a wellbore and cemented. The purpose of the casing pipe is as follows:

• prevent the collapse of the borehole
• prevent formation fluids from entering the borehole in an uncontrolled way (blow out)
• prevent fluids in the borehole ( such as produced oil or gas, drilling mud etc.) from entering other formations