What Are The Methods for Lowering Casing for Oil Casing Pipe?

1. Conventional Casing Running

This is the most common method employed for lowering oil casing. It generally involves:

Casing String Assembly: The casing pipe is assembled on the rig floor, connecting multiple sections or joints.

Lifting: The casing is lifted using a hoisting system, typically a drilling rig’s hook or elevators.

Lowering: The casing is lowered into the wellbore by engaging the drill pipe or casing with the hoisting system. This is done at a controlled speed to prevent damage.

2. Casing with a Casing Running Tool (CRT)

Casing Running Tools are specialized tools designed to facilitate the running and positioning of casing:

Mechanical Advantage: CRTs provide a mechanical advantage during casing operations and help in the proper alignment, reducing the likelihood of the casing sticking or getting hung up in the wellbore.

Controlled Lowering: These tools can control the rate of descent and offer better handling in challenging conditions like narrow or crooked wellbores.

3. Hydraulic Casing Running Tools

These tools use hydraulic pressure to aid in the lowering and positioning of casing strings:

Hydraulic Control: Operators can adjust lowering speed and position with fine control, improving safety and accuracy.

Suitable for Complex Operations: Particularly useful in deep or complex wellbores where traditional techniques might be difficult.

4. Casing with Blowout Preventer (BOP)

When running casing in high-pressure or offshore environments, using a BOP system is essential:

Preventive Setup: The BOP is installed on the ocean floor or wellhead and monitored while the casing is being run to prevent any potential blowout during the operation.

Controlled Environment: This method provides a controlled environment while lowering the casing.

5. Float Equipment

Float equipment can be used during casing operations to enable easier lowering and to prevent fluids from entering the casing:

Float Shoe/Floats: A float shoe is installed at the bottom of the casing string. It allows for the casing to be lowered while preventing backflow of cement or other fluids into the casing.

6. Casing Handlers

Casing handlers are specialized rigs or equipment designed to assist with casing operations:

Automation: These systems can automate the lowering process to improve accuracy and safety.

Safe Operation: They allow for reduced manual handling, minimizing the risk of accidents.

7. Gravity Lowering

In some cases, gravity can be used as a method to lower the casing:

Controlled Descent with Weight: Using the weight of the casing string itself to guide it into the wellbore at a controlled speed. Typically less common as operational conditions often necessitate more controlled techniques.

8. Casing Drilling (with DRILLED Casing)

This technique involves drilling with casing rather than traditional drilling methods:

Simultaneous Operations: During drilling, the casing is simultaneously lowered, reducing the risk of wellbore collapse in unstable formations.