Drilling Riser conductor Casing BTC 18 5/8" J55 87.5ppf
In order to prevent the collapse of the loose layer on the surface of the borehole, the upper fresh water layer is sealed to prevent it from being polluted by the drilling work and the casing run by installing the wellhead blowout preventer. The running depth of surface casing should be determined according to the depth of unconsolidated formation and the fracture pressure gradient of upper formation. The diameter of surface casing is determined by the number of casing layers and the diameter of production casing.
