Drillable

Drillable: A Vital Component in Drilling & Well Completion

In the world of drilling and well completion, the term "drillable" refers to any downhole tool or equipment designed to be intentionally broken up by the drill bit during the drilling process. This practice allows for efficient removal of tools and equipment no longer needed, preventing obstruction and streamlining operations.

Here's a breakdown of commonly drillable tools and equipment, along with their functions and why they are designed to be "drillable":

1. Drill String Components:

• Drill collars: These heavy, thick-walled steel components are used to apply weight to the drill bit and provide stability to the drill string. Once the desired depth is reached, drill collars can be drilled out to reduce weight on the bit.
• Drill pipe: The primary component of the drill string, drill pipe connects the surface equipment to the drill bit. While not commonly drillable, in some instances, the top few joints of drill pipe may be designed to break apart in case of a stuck pipe incident.
• Stabilizers: These tools are used to control the trajectory of the drill string. While not intended to be drilled out, stabilizers are sometimes designed with a weak point that allows them to break off if they become stuck.

2. Downhole Tools:

• Reamer: A reamer is used to enlarge the hole drilled by the bit, ensuring smooth flow of drilling mud. Reamer sections are often designed with a weakened area that allows them to break apart once their function is fulfilled.
• Centralizers: These tools keep the drill string centered within the wellbore, preventing it from contacting the sides. Centralizers can be made from drillable materials to avoid obstructing the flow path.
• Scrapers: Scrapers are used to remove debris from the bottom of the hole during drilling. They are often designed to break apart when no longer needed, allowing for efficient removal.
• Underreamers: Underreamers are similar to reamers but are used to enlarge the hole at a specific depth, commonly around the wellbore casing. Their design allows them to be drilled out once their function is complete.

3. Completion Equipment:

• Temporary Packers: Temporary packers are used to isolate a section of the wellbore during drilling or completion operations. They are designed to be drilled out when their purpose is fulfilled.
• Completion Strings: In some cases, a completion string containing valves, tubing, and other equipment may be lowered into the wellbore during drilling. Certain components of this string can be designed to be drillable to facilitate efficient completion operations.

Why Drillable?

The "drillable" design philosophy offers several advantages in drilling and well completion:

• Simplified Operations: By allowing tools and equipment to be broken up, it eliminates the need for complex retrieval operations, saving time and resources.
• Reduced Risk of Stuck Pipe: The ability to break apart tools prevents them from becoming stuck in the wellbore, a costly and potentially dangerous scenario.
• Improved Flow Efficiency: By removing unnecessary equipment from the wellbore, drillable tools contribute to a smoother flow path for oil and gas production.

Conclusion

The use of drillable downhole tools and equipment plays a crucial role in achieving efficient and safe drilling and well completion operations. By understanding the design and function of these tools, engineers can optimize drilling strategies, minimize downtime, and ensure the efficient production of oil and gas resources.