Runaway (coiled tubing)

Runaway: The Unwanted Journey of Coiled Tubing

In the oil and gas industry, coiled tubing is a versatile tool used for various well intervention operations. This flexible tubing, wound on a large spool, is deployed downhole to perform tasks like well stimulation, cleaning, and production enhancement. However, sometimes this controlled operation can turn into a dangerous and costly event – a runaway.

What is a Runaway (Coiled Tubing)?

A runaway, in the context of coiled tubing, refers to the uncontrolled run-in of the tubing into the wellbore. This unexpected movement can be triggered by various factors, including:

• Excessive weight on the tubing: When the weight applied to the tubing exceeds the frictional resistance in the well, it can overcome the holdback and uncontrollably descend.
• Loss of friction: If the wellbore conditions change, like a decrease in the coefficient of friction or a sudden release of pressure, the tubing can lose its grip and accelerate downwards.
• Equipment malfunction: A failure in the holding mechanism or the brake system can lead to an uncontrolled run-in.

Consequences of a Runaway:

A runaway situation can have severe consequences, both for the equipment and the wellbore itself:

• Tubing damage: The uncontrolled descent can cause the tubing to buckle, kink, or even break.
• Wellbore damage: The rapid movement can damage the wellbore, including the casing, cement, and formation.
• Personnel safety: A runaway can pose a serious hazard to personnel working on the rig due to the potential for uncontrolled movement and high-pressure releases.
• Environmental risks: Damage to the wellbore can lead to uncontrolled fluid releases and environmental contamination.
• Financial losses: Repairing the damage and replacing the damaged tubing can lead to significant financial losses.

Preventing Runaways:

Preventing a runaway requires a combination of preventive measures, including:

• Proper weight management: The weight applied to the tubing must be carefully calculated to ensure it remains within safe limits.
• Monitoring wellbore conditions: Regular monitoring of wellbore conditions like pressure and friction can help detect potential risks.
• Equipment maintenance: Ensuring that all equipment involved in the operation is in good working order and properly maintained is crucial.
• Emergency procedures: Implementing clear and well-rehearsed emergency procedures for handling a runaway situation can minimize damage and ensure personnel safety.

Conclusion:

A runaway coiled tubing situation is a serious risk that can have significant consequences. Understanding the causes, potential consequences, and preventive measures is essential for ensuring safe and efficient coiled tubing operations. By implementing best practices and being prepared for unexpected events, the oil and gas industry can minimize the risk of runaways and ensure the safety and well-being of personnel, the environment, and the integrity of the well.