Preparing Casing

A casing is a large diameter pipe that is inserted into the hole and casing is run (lowered in the hole) as soon as the hole has been drilled and should be secured in place by cementing and it should be inspected before running it to make sure all joints are in a good condition for tools and equipment to be able to pass through it later on. The procedure of preparing casing is below:

1. Remove the casing/thread protectors.

2. Inspect the pipe for physical damage to the tubular body and ends.

3. Look for any damage to determine if the joint is suitable for downhole use.

4. Check the thread to see if they have any damages.

5. Drift the tubulars before cleaning the threads. The rabbit can pull dirt and other objects through the end of the pipe. Drifting the casing is to check that the internal diameter of the casing meets the specified tolerance. A tool called a drift or rabbit is run through the length of the casing to check the internal diameter.

Casing is needed to:

• Maintain borehole stability.

• Prevent contamination of water aquifer.

• Isolate water from producing formations.

• Control well pressures during drilling, production, and workover operations. Casing provides base or connection for the installation of:

• Blowout preventers.

• Wellhead equipment.

• Production packers.

• Production tubing.

The cost of casing is a major part of the overall well cost, so selection of casing size, grade, connectors, and setting depth is a primary engineering and economic consideration.