(1) guide bush: mainly used in Marine, drilling in the desert, to separate water and sand, ensure the smooth progress of the drilling the main specifications of this layer casing is: Ø (30) in 762 mm x 25.4 mm, 762 mm (30) in Ø x 19.06 mm.
(2) surface casing: mainly used for the first drilling, drilling surface soft strata to bedrock, in order to seal this part of the strata will not collapse, surface casing for sealing.Main specifications of surface casing: 508mm(20in), 406.4mm(16in), 339.73mm(13-3/8in), 273.05mm(10-3/4in), 244.48mm(9-5/8in), etc.The depth of the lower pipe depends on the depth of the soft stratum, which is generally 80~1500m.The external pressure and internal pressure it bears are not big, generally use K55 steel class or N80 steel class.
(3) technical casing: used in the drilling process of complex strata, when the collapse layer, oil layer, gas layer, water layer, leakage layer, salt-paste layer and other complex parts, need technical casing sealing, otherwise the drilling can not be carried out.Some Wells are deep and complicated, and the drilling depth is thousands of meters. Such Wells need several layers of technical casing, and the mechanical properties and sealing performance are very high. The steel grade is also high.The main specifications of technical casing are: 339.73mm(13-3/8in), 273.05mm(10-3/4in), 244.48mm(9-5/8in), 219.08mm(8-5/8in), 193.68mm(7-5/8in), 177.8mm(7in), etc
(4) oil layer casing: when drilling to the target layer (oil, gas layer), it is necessary to use the oil layer casing to seal the oil and gas layer and the upper exposed strata, the oil layer casing is the tubing.The casing of oil layer is the deepest in all kinds of casing, and its mechanical properties and sealing performance are also the highest. The steel grades are K55, N80, P110, Q125 and V150, etc.The main specifications of reservoir casing are: 177.8mm(7in), 168.28mm(6-5/8in), 139.7mm(5-1/2in), 127mm(5in), 114.3mm(4-1/2in), etc.