Welded Casing Types
Welded casing is essential in drilling operations, serving as robust steel liners that stabilize the wellbore, seal surrounding formations, and withstand high pressures. Typically fabricated using electric-resistance or spiral welding techniques, these casings offer durability and integrity.
There are several welded casing types used across various well sections:
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Conductor Casing (Drive Pipe): The first, largest-section casing, usually installed before drilling begins. It stabilizes the ground near the surface and supports the rig.
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Surface Casing: Protects groundwater zones and allows attachment of safety equipment like blowout preventers.
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Intermediate Casing: Isolates high-pressure or unstable formations during deeper drilling stages.
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Production Casing: Runs through the reservoir, providing a conduit for oil and gas while preventing formation cross-communication.
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Liner: A partial casing that doesn’t extend to the surface, used to isolate problematic sections cost-effectively.
Welded versions of these casings are manufactured using longitudinal electric-resistance welding or spiral welding. They provide seamless strength and comply with ASTM or API standards. The welds are heat-treated to improve toughness and reduce the risk of brittleness.
