Definition - What does Casing mean?
Casing, also known as well casing, is a pipe with a large diameter that is assembled, inserted and cemented into a section of a recently drilled wellbore. It is designed in such a way that it can withstand various forces like burst, collapse and tensile failure, and chemically excessive brines as well. Running pipe is the operation during which the casing is done.
Petropedia explains Casing
Oil well casing is inserted during a running pipe operation into a borehole and held in place with cement. It helps the drilling process in many ways like preventing fresh water contamination, unstable upper formations, isolating various zones with different pressures in drilled formations. This steel pipe is cemented in place in order to stabilize the borehole during the construction process. It forms a major structural component of the borehole and performs several functions. The casing can be found based on the range of sizes and the material grades. The casing design for each size is done by measuring the worst conditions that can be faced during production and drilling.