Uses of OCTG Casing
Guide Casing
Guide casing is mainly used for drilling in the ocean and desert to separate water and sand and ensure the smooth progress of drilling. The main specifications of this layer of casing are: φ(30) inches × 762 mm × 25.4 mm, φ(30) inches × 19.06 mm.
Surface Casing
Surface casing mainly used for the first drilling, drilling the soft surface layer to the bedrock, in order to seal this part of the formation will not collapse, the surface casing is sealed. Surface casing main specifications: 508 mm (20 inches), 406.4 mm (16 inches), 339.73 mm (13-3/8 inches), 273.05 mm (10-3/4 inches), 244.48 mm (9-5/8 inches) inches) etc. The downpipe depth depends on the depth of the soft formation, generally 80~1500m. The external pressure and internal pressure it bears are not large, generally K55 steel grade or N80 steel grade is used.
Technical Casing
Surface casing is used in the drilling process of complex formations, when encountering complex parts such as slump layers, oil layers, gas layers, water layers, leakage layers, salt-gypsum layers, etc., technical casing sealing is required, otherwise drilling cannot be performed. conduct. Some wells are deep and complex, with drilling depths of thousands of meters. Such wells require several layers of technical casing with high demands on mechanical and sealing properties. The grade of steel is also high. The main specifications of technical casing are: 339.73mm (13-3/8"), 273.05mm (10-3/4"), 244.48mm (9-5/8"), 219.08mm (8-5/8") ), 193.68 mm (7-5/8 inches), 177.8 mm (7 inches), etc.
Oil layer Casing
When drilling to the target layer (oil and gas layers), it is necessary to seal the oil and gas layer and the upper exposed formation with oil layer casing, and the oil layer casing is the oil pipe. The oil layer casing is the deepest among all kinds of casings, 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: 177.8 mm (7 inches), 168.28 mm (6-5/8 inches), 139.7 mm (5-1/2 inches), 127 mm (5 inches), 114.3 mm (4-1/2 inches) 1/2 inch) etc.
