crown saver

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.

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.

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.

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.

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.

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.

Techniques

Crown Saver: A Deep Dive

Here's a breakdown of the crown saver technology, organized into chapters:

Chapter 1: Techniques

Crown savers employ a straightforward yet effective technique based on line length monitoring and immediate response. The core technique involves:

1. Line Length Sensing: A primary method involves a mechanical probe that physically senses the amount of drilling line wound onto the drawworks drum. As the line approaches a pre-determined critical length (indicating proximity to the crown block), the probe activates the safety mechanisms. Alternatively, more advanced systems might use non-contact sensors such as ultrasonic or optical sensors to measure the line length. This allows for a less mechanical solution, potentially reducing wear and maintenance.

2. Immediate Safety Activation: Upon detection of excessive line length, the system immediately triggers two simultaneous actions:

   • Power Cut-off: The power supply to the drawworks is immediately interrupted, halting any further upward movement of the traveling block.
   • Brake Engagement: The drawworks brakes are instantly engaged, firmly securing the traveling block in its current position. This prevents any uncontrolled descent should the power cut-off fail.

3. Fail-safe Design: The design philosophy emphasizes redundancy and fail-safe operations. Multiple sensors or a dual-sensor system can be implemented for increased reliability. The brakes are designed to engage even in the event of power failure, ensuring a secondary safety net.

4. Calibration and Adjustment: Crown savers require regular calibration to account for variations in line diameter, wear, and other factors. The critical line length setting needs to be adjusted to match the specific rig configuration.

Chapter 2: Models

Crown savers come in various models, each with its own features and capabilities. The choice of model depends on the specific requirements of the drilling rig and the operating environment. Key variations include:

1. Mechanical vs. Electronic: The simplest models rely solely on mechanical probes and switches, while more advanced systems incorporate electronic sensors, microprocessors, and programmable logic controllers (PLCs) for more precise monitoring and control. Electronic models often offer features like data logging, remote monitoring, and customizable safety parameters.

2. Single vs. Dual Sensor Systems: Single sensor systems are cost-effective but rely on a single point of failure. Dual sensor systems offer greater reliability and safety by providing redundancy. If one sensor fails, the other continues to monitor line length.

3. Integrated vs. Add-on Systems: Some crown savers are integrated directly into the drawworks design, while others are added as aftermarket safety enhancements. Integrated systems often offer a more seamless and reliable solution.

4. Different Probe Technologies: As mentioned in the techniques section, the type of probe used (mechanical lever, ultrasonic, optical) can impact accuracy, maintenance, and cost.

Chapter 3: Software

More sophisticated crown saver models utilize embedded software for control and data management. This software:

1. Monitors Line Length: Continuously monitors the length of drilling line on the drawworks drum, comparing it to the pre-set critical length.

2. Triggers Safety Mechanisms: Instantly activates the power cut-off and brake engagement when the critical line length is exceeded.

3. Data Logging and Reporting: Records important parameters such as line length, activation times, and other relevant data, providing valuable information for analysis and maintenance. This information can be used to identify potential problems and improve safety procedures.

4. User Interface: May include a user-friendly interface for setting parameters, viewing data, and performing diagnostics. This could be a local display on the crown saver unit or a remote interface integrated into the rig's overall control system.

Chapter 4: Best Practices

Implementing and maintaining crown savers effectively requires adherence to best practices:

1. Regular Inspection and Maintenance: Regular inspections are critical to ensure that all components are functioning correctly. This includes checking the probe, sensors, wiring, brakes, and power connections. A preventative maintenance schedule should be implemented.

2. Proper Calibration: The crown saver should be calibrated regularly to maintain accuracy. This involves adjusting the critical line length setting to match the specific rig configuration and line conditions.

3. Operator Training: Rig personnel must receive thorough training on the operation and maintenance of the crown saver. They need to understand the system's limitations and how to respond in the event of an activation.

4. Emergency Procedures: Clear emergency procedures should be in place in case of a crown saver activation. This includes steps to ensure the safety of personnel and the prevention of further damage.

5. Integration with Rig Systems: The crown saver should be integrated seamlessly with other rig safety systems for a comprehensive approach to accident prevention.

Chapter 5: Case Studies

(This section would require specific examples of crown saver implementations and their impact. Ideally, this would include details of averted accidents, cost savings from prevented downtime, and improvements in safety performance metrics.) For example:

• Case Study 1: A hypothetical example of a rig that avoided a catastrophic crown hit due to the timely activation of a crown saver, detailing the circumstances, the averted damage, and the cost savings.
• Case Study 2: A comparative study comparing the safety records of rigs with and without crown savers, highlighting the significant reduction in incidents in rigs equipped with the device.
• Case Study 3: An example showcasing how regular maintenance and operator training played a critical role in the effective functioning of a crown saver system. This might discuss a case where a potential failure was detected during a routine inspection, preventing a serious incident. The specific details will depend on the availability of real-world data and case studies from drilling companies.