A steel or plastic pipe that serves as the lining of a well, preventing it from caving in, and protecting groundwater from contamination by surface water.

Well casing refers to the steel tubes which are cemented into a wellbore following drilling. This casing provides a variety of functions including the prevention of fresh water contamination and cave-ins. Usually several layers of well casing are used to ensure continued well integrity.

The layer of metal that surrounds the wellbore to provide structural integrity and to prevent loss of fluids. Multiple layers of casing and cement are used to prevent loss of fluids into sensitive roc [..]