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What is Oil casing?
- May 31, 2018 -

Casing is large diameter pipe that is assembled and inserted into a recently drilled section of a borehole and typically held in place with cement.

Casing that is cemented in place, aids the drilling process in several ways:

  • Prevent contamination of fresh water well zones.

  • Prevent unstable upper formations from caving in and sticking the drill string or forming large caverns.

  • Provides a strong upper foundation to use high-density drilling fluid to continue drilling deeper.

  • Isolates different zones, that may have different pressures or fluids - known as zonal isolation, in the drilled formations from one another.

  • Seals off high pressure zones from the surface, avoiding potential for a blowout

  • Prevents fluid loss into or contamination of production zones.

  • Provides a smooth internal bore for installing production equipment.

Casing arranged on a rack at a drilling rig in preparation for installation

A slightly different metal string, called production tubing, is often used without cement in the smallest casing of a well completion to contain production fluids and convey them to the surface from an underground reservoir.

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