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What is Oil Country Tubular Goods(OCTG)?

Release time:

2026-03-01

Author:

Lynn Chow

Source:

Comprehensive Analysis of OCTG Pipe&Tubing (Oil Country Tubular Goods)

OCTG (Oil Country Tubular Goods) is a core metal pipe essential for oil and gas exploration, development and production. It is widely used in drilling, completion, cementing and transportation, undertaking key tasks such as well wall support, formation isolation and oil-gas conduction. As the "lifeline" of oil and gas wells, its quality directly determines well service life and operational safety. OCTG pipe&tubing mainly includes Casing and Tubing, plus auxiliary components, forming a complete system.

I. Core Types and Uses of OCTG Pipe&Tubing

OCTG pipe&tubing is mainly divided into casing, tubing and auxiliary pipes, each with distinct functions to adapt to different oil and gas extraction links.

(I) Casing: The "Protective Barrier" of Well Walls

Casing is a large-diameter pipe cemented to the well wall to prevent collapse, isolate formations and protect wellheads. It is divided into 4 types by depth and function:

Conductor: OD > 20 inches, depth 50-250 feet, fixes wellhead and stabilizes surface soil, the "first line of protection".

Surface Casing: OD 13⅜-16 inches, protects shallow fresh water layers and ensures subsequent drilling safety.

Intermediate Casing: OD 9⅝-13⅜ inches, isolates high-pressure/corrosive formations in middle-deep wells.

Production Casing: OD 4½-7 inches, contacts production layers directly, protects layers and supports tubing.

(II) Tubing: The "Transport Channel" for Oil and Gas

Tubing transports oil and gas from well bottom to surface, requiring high corrosion resistance and sealing. It is divided into 3 types by size:

Small-sized: OD 1.050-2.375 inches, for low-pressure, low-yield shallow wells.

Medium-sized: OD 2.875-3.500 inches, the most common, for conventional output wells.

Large-sized: OD 4.000-4.500 inches, for high-yield, high-pressure wells.

(III) Auxiliary Pipes

Key auxiliary components include Pup Joints (adjust pipe length) and Couplings (connect pipes, ensure sealing and strength), which are vital for the complete OCTG system.