Guidelines for the Use of Oil and Gas Casing and Tubing
Date:2026-07-09
During the preliminary preparation stage, the transportation and storage of casing and tubing require great care. Non-metallic slings must be used during lifting to prevent impact damage; for storage, the pipes must be elevated at least 120 mm off the ground using wooden or non-metallic supports. They must not be stored outdoors, and pipes of different materials must be kept separate to avoid any mix-ups.
Before running the pipe into the well, every joint must undergo a drift test to ensure the internal bore is clear and unobstructed. Additionally, threads and sealing surfaces must be meticulously inspected; any minor damage could pose a safety risk and requires the pipe to be set aside for remediation.
Moving to the core operational phase: before running the pipe, threads and sealing surfaces must be thoroughly cleaned and dried with compressed air, followed by the even application of specialized thread compound compliant with API RP 5A3 standards. Special attention is required for pipes made of special materials like 13Cr; only nylon brushes may be used for cleaning—steel wire brushes are strictly prohibited.
During the make-up process, the threads must first be engaged manually to ensure proper alignment. Subsequently, hydraulic tongs equipped with a torque monitoring system are used for mechanical tightening, typically at a rotational speed not exceeding 25 revolutions per minute. The make-up torque must be precisely controlled within specified limits and verified via torque curves to ensure a reliable seal at the connection.
Operational requirements vary depending on the specific working environment. For instance, when handling corrosion-resistant alloy pipes (such as 13Cr), nylon slings must be used for lifting, and rubber pads must be placed on pipe racks and catwalks. Make-up tools must utilize non-marking slips and tongs to prevent scratching the pipe body, which could otherwise trigger stress corrosion cracking.
Throughout the running and pulling operations, the lowering speed of the pipe string must not be excessive—particularly in deviated wells—and is usually controlled at 0.15 to 0.20 meters per second to prevent impact loads from damaging the threads. During lowering, the casing must also be filled with fluid to reduce friction against the wellbore and minimize the risk of getting stuck.
The reason for such rigorous standards is fundamental: casing and tubing constitute the "lifeline" of an oil well. Even a minor operational error can damage the pipe body; given the complex mechanical and corrosive conditions downhole, such slight damage can trigger serious issues or even result in the total loss of the well. These precise operational protocols are primarily based on relevant American Petroleum Institute (API) standards.
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