The distinction between oil casing and oil drill pipe can be summarized into two primary aspects: their respective applications and the materials they are made from.
Oil casing serves as a steel conduit that bolsters the walls of oil and gas wells, ensuring the integrity and functionality of the well throughout the drilling process and beyond. Depending on the drilling depth and geological characteristics, multiple casing layers are employed in each well. Once the casing is positioned in the well, cement is applied to secure it in place. Unlike other types of pipes used in drilling, oil casing is a single-use item and cannot be reused, which is why it constitutes over 70% of the total consumption of oil well pipes. Casing can be categorized into guide tubes, surface casings, technical casings, and production casings based on their specific functions.
Drill pipes, on the other hand, are the rods that are linked together in drilling equipment to transfer power. The typical components of a drill string include the drill bit, drill collar, drill pipe, stabilizer, special joints, and square drill pipes. The drill string's fundamental roles are to：
(1) raise and lower the drill bit
(2) apply pressure for drilling
(3) convey power
(4) transport drilling fluids
(5) carry out specialized operations such as cement squeezing and managing subsurface incidents.
Oil drill pipes are available in a variety of steel grades from API standard E75 to S135 and come in sizes with outer diameters ranging from 2 3/8″ to 6 5/8″. They also include double-shoulder joint drill pipes with enhanced torsional resistance and special-grade BNK C95S drill pipes designed for wells containing sulfur. These pipes are predominantly utilized in the construction of deep wells, horizontal wells, and extended-reach wells during the exploration and development of oil and gas resources.
