Drilling & Well Completion

crown saver

Crown Saver: A Safety Lifeline in Drilling Operations

In the high-stakes world of oil and gas drilling, safety is paramount. One crucial aspect of rig safety lies in preventing a potentially catastrophic event: the traveling block colliding with the crown block. This scenario, known as a "crown hit," can lead to severe damage to the rig, injury to personnel, and costly downtime. To mitigate this risk, a safety device called a crown saver plays a crucial role.

What is a Crown Saver?

A crown saver is a mechanical device mounted near the drawworks drum of a drilling rig. It acts as a safety barrier, preventing the driller from accidentally raising the traveling block too high and into the crown block. This device employs a simple yet effective mechanism:

  • Probe: A probe, usually a lever or sensor, is positioned near the drawworks drum. It senses when an excessive amount of drilling line has been pulled onto the drum, indicating that the traveling block is getting too close to the crown block.
  • Activation: When the probe detects a critical line length, it activates a switch. This action triggers two simultaneous safety measures:
    • Power Disconnect: The drawworks are immediately disconnected from their power source, preventing any further movement of the traveling block.
    • Brake Engagement: The drawworks brake is automatically engaged, firmly holding the traveling block in its current position.

How Does a Crown Saver Work?

The crown saver is designed to be a last line of defense against a crown hit. As the driller operates the drawworks, the crown saver continually monitors the amount of line on the drum. If the driller inadvertently pulls too much line, the probe senses this and activates the safety mechanisms.

Benefits of a Crown Saver:

  • Prevents catastrophic accidents: The crown saver acts as a failsafe system, preventing a crown hit and the associated risks of damage, injury, and downtime.
  • Ensures operator safety: By preventing the traveling block from colliding with the crown block, the crown saver significantly improves the safety of the rig crew.
  • Reduces downtime and repair costs: Avoiding a crown hit prevents costly repairs to the rig and minimizes downtime, leading to increased operational efficiency.

Conclusion:

The crown saver is an essential safety device that plays a critical role in modern drilling operations. It acts as a final safety barrier, preventing a potentially catastrophic crown hit. By integrating this device into drilling rigs, operators can significantly enhance rig safety, reduce downtime, and maintain operational efficiency. The crown saver serves as a reminder that safety should always be paramount, even in the demanding environment of oil and gas drilling.


Test Your Knowledge

Crown Saver Quiz

Instructions: Choose the best answer for each question.

1. What is the primary purpose of a crown saver? a) To prevent the traveling block from colliding with the crown block. b) To lubricate the drawworks drum. c) To monitor the weight on the drill string. d) To control the speed of the drilling operation.

Answer

a) To prevent the traveling block from colliding with the crown block.

2. How does a crown saver typically detect an impending crown hit? a) By measuring the pressure in the drilling fluid. b) By sensing the amount of line on the drawworks drum. c) By monitoring the rotation speed of the drill bit. d) By measuring the temperature of the drill string.

Answer

b) By sensing the amount of line on the drawworks drum.

3. What actions does a crown saver take when it detects an impending crown hit? a) It stops the drilling operation and alerts the crew. b) It automatically disconnects the power and engages the brakes. c) It increases the drilling fluid pressure to prevent a blowout. d) It reduces the weight on the drill string to avoid a stuck pipe.

Answer

b) It automatically disconnects the power and engages the brakes.

4. What is the main benefit of using a crown saver in drilling operations? a) It improves the efficiency of the drilling process. b) It reduces the risk of a catastrophic accident. c) It simplifies the operation of the drawworks. d) It increases the drilling depth achievable.

Answer

b) It reduces the risk of a catastrophic accident.

5. Which of the following statements is NOT true about a crown saver? a) It is a mechanical device mounted near the drawworks drum. b) It acts as a safety barrier in drilling operations. c) It is designed to prevent a blowout. d) It can help to ensure operator safety.

Answer

c) It is designed to prevent a blowout.

Crown Saver Exercise

Scenario: Imagine you are a drilling supervisor on a rig. The driller is raising the traveling block to connect a new drill string section. Suddenly, the crown saver activates, stopping the block's movement.

Task: Explain the likely cause of the crown saver activation, the immediate steps you would take, and the long-term actions to prevent such incidents in the future.

Exercice Correction

**Likely Cause:** The driller likely pulled too much line onto the drawworks drum, bringing the traveling block too close to the crown block. This could have been due to misjudging the line length or a malfunction in the line counter. **Immediate Steps:** 1. **Stop all operations:** Ensure the traveling block is securely held and the rig is in a safe condition. 2. **Investigate the cause:** Check the line counter, the crown saver probe, and the amount of line on the drum. 3. **Communicate with the crew:** Inform everyone about the situation and the necessary precautions. 4. **Reset the crown saver:** Ensure the crown saver is functioning correctly and ready for the next operation. **Long-Term Actions:** 1. **Train the driller:** Emphasize proper line management and the importance of using the line counter accurately. 2. **Inspect the crown saver:** Regularly check the crown saver for proper functioning, wear, and tear. 3. **Implement safety procedures:** Ensure a clear set of procedures are in place for handling the drawworks and connecting drill string sections. 4. **Review the incident:** Discuss the incident with the crew to identify any weaknesses in procedures or training, and implement necessary adjustments.


Books

  • Drilling Engineering: This comprehensive text by Bourgoyne, Millheim, Chenevert, and Economides covers all aspects of drilling, including safety equipment like crown savers.
  • Petroleum Engineering Handbook: This handbook contains sections dedicated to drilling and production equipment, including chapters on safety mechanisms and drilling rig design.

Articles

  • "Crown Hit Prevention Systems" by [Author Name]: Search for articles published in journals like "SPE Drilling & Completion," "Journal of Petroleum Technology," or "World Oil" for specific technical articles on crown saver systems.
  • "Safety Features on Modern Drilling Rigs" by [Author Name]: Look for articles published in industry publications or trade magazines that discuss safety innovations in drilling operations.

Online Resources

  • API (American Petroleum Institute) Standards: API publishes standards and recommended practices for various aspects of drilling operations, including safety equipment. Search for relevant standards related to crown savers.
  • IADC (International Association of Drilling Contractors) Publications: IADC provides educational resources and industry best practices for drilling contractors, including information on safety devices.
  • Rigzone.com: This website contains articles, news, and technical resources for the oil and gas industry, including sections on drilling operations and safety.

Search Tips

  • Use specific keywords: Use phrases like "crown saver," "crown hit prevention," "drilling rig safety," "drawworks safety," and "drilling equipment safety" to refine your search.
  • Combine keywords with specific rig types: For example, search for "crown saver jackup rig" or "crown saver offshore drilling rig" to find more relevant results.
  • Include relevant publications: Use keywords like "API standards" or "IADC publications" to limit your search to specific industry sources.
  • Search for patents: Use keywords like "crown saver patent" to find information on the design and operation of different crown saver systems.

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