Different types of casing used in oil extraction include:
Conductor casing is the first string of casing installed in the well structure; it serves to isolate seawater, guide the drill bit into the well and direct drilling mud returning from the wellhead to the mud pit, seal off loose and unstable formations beneath the seabed, and support the weight of the surface, intermediate, and production casing strings.
Surface casing is used to seal off unstable, soft upper formations, aquifers, and shallow gas zones; it allows for the installation of wellhead equipment to control well kicks and blowouts, while also supporting the weight of intermediate and production casing strings or liners.
Intermediate casing is used to isolate complex formations that are difficult to control, thereby ensuring the smooth progress of drilling operations.
Production casing serves to isolate oil, gas, and water zones and establish a conduit for long-term hydrocarbon extraction.
Liners are categorized by function into drilling liners, production liners, tie-back liners, and others.
Additionally, based on the threading configuration at the ends, oilfield casing can be classified into types such as short round thread, long round thread, buttress thread, and special connection casing.
