1.Surface Casing: Extends from the wellhead to the shallow stable formation, with a typical depth ranging from tens to hundreds of meters (specifically determined by the thickness of surface soil layers and geological conditions).
2.Intermediate Casing: Located below the surface casing, extending to the complex formation section above the target zone (oil and gas reservoir), with a depth that can reach several thousand meters (adjusted according to geological complexity).
3.Production Casing:Penetrates the target zone (oil and gas reservoir), usually extending from the bottom of the intermediate casing to a certain depth below the oil and gas reservoir, and is one of the deepest-set casing types.
