Casing is the major structural component of a well. Casing is needed to: Maintain borehole stability Prevent contamination of water sands Isolate water from producing formations Control well pressures during drilling, production, and workover operations Casing provides locations for the installation of: Blowout preventers Wellhead equipment Production packers Production tubing The cost of casing is a major part of the overall well cost, so selection of casing size, grade, connectors, and setting depth is a primary engineering and economic consideration.
