casing

Casing is a large-diameter pipe that serves as the structural retainer for the walls of oil and gas wells, or wellbore, it is inserted into a well bore and cemented in place to protect both subsurface formations and the wellbore form collapsing and to allow drilling fluid to circulate and extraction to take place. Casing pipes are ordinarily produced with outside diameter sizes of 114.3mm to 508.0mm