Introduction
Surface casing: install casing head at the top, and hang and support the casing of subsequent layers through the casing head; It separates the surface shallow water layer and the shallow complex bottom layer, and is a fresh water layer that is not polluted by drilling fluid Intermediate casing (technical casing): it is used to isolate strata with different formation pressures or complex formations with easy collapse and leakage.
Production casing: it protects the production layer and provides a channel for oil and gas to flow from the production layer to the surface.
Drilling liner: reduce the load of drilling rig during casing running and the load of casing head after cementing, save a lot of casing and cement, and reduce cementing cost.
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