Surface casing and conductor casing for conventional onshore oil and gas wells in Colombia.
20″ K55 BTC is the standard surface casing specification for medium-depth conventional onshore wells in South America. At 106.5 ppf (158.4 kg/m), this is one of the heavier weights in the 20″ range — selected when the operator needs higher collapse resistance, greater cement annular volume control, or simply prefers the additional wall thickness margin for the tophole section where borehole conditions are often less predictable.
K55 grade (minimum yield 379 MPa / 55 ksi) provides adequate strength for surface casing loads without the cost premium of N80 or higher-grade steel. BTC connection was specified for its proven track record in surface casing applications: its square-shoulder buttress thread achieves 100% pipe-body tensile efficiency in most weights and seals adequately for the liquid-service conditions typical of shallow surface casing.
Application profile: 20″ surface casing isolates the freshwater zones and stabilises the tophole section before drilling ahead to intermediate depths. In conventional Colombian onshore fields, surface casing is typically set between 150 m and 600 m depth, meaning collapse and burst loads are modest — the governing design load is usually hook load during installation and cementing.
ZC Steel Pipe supplied this 208-piece order with API 5CT PSL1 MTC, BTC gauge inspection records, and thread compound pre-applied to pin and coupling. Pipe ID stencilling confirmed grade, size, weight, and heat number on each joint.