Burn Over

Test Your Knowledge

Quiz: Burn Over in Oil & Gas Equipment Recovery

Instructions: Choose the best answer for each question.

1. What is the primary purpose of a "burn over" in the oil and gas industry?

a) To clean the wellbore b) To stimulate oil production c) To recover stuck equipment downhole d) To prevent well blowouts

2. Which of the following is NOT a key component of a burn over operation?

a) Milling tool b) Overshot c) Drilling mud d) Wireline

3. Why is a burn over considered a cost-effective solution for equipment recovery?

a) It utilizes readily available materials. b) It is a very fast process. c) It saves the expense of replacing the equipment. d) It minimizes environmental impact.

4. Which of the following is a potential disadvantage of a burn over operation?

a) It can cause excessive wellbore damage. b) It can lead to increased production. c) It is only effective for specific types of equipment. d) It requires minimal specialized equipment.

5. What is the primary role of the overshot in a burn over operation?

a) To mill the stuck equipment b) To secure the milling tool c) To grab and lift the milled section of the equipment d) To prevent wellbore collapse

Exercise:

Scenario: A drill string has become stuck downhole. The drilling team decides to attempt a burn over to recover the stuck equipment. Explain the steps involved in a burn over operation, outlining the roles of the milling tool, overshot, and wireline.

Techniques

Chapter 1: Techniques

Burn Over: A Detailed Look at the Procedure

The "burn over" technique is a crucial step in the recovery of stuck equipment in oil and gas wells. This process involves using specialized tools to mill a section of the stuck equipment, typically a drill string, and then catching it with an overshot. Here's a breakdown of the steps involved:

1. Milling: A specialized milling tool is lowered downhole, guided by the drill string. This tool is equipped with cutting blades designed to remove a section of the stuck equipment, creating a weakened area. The milling tool may be a standard mill, a directional mill, or a rotary mill, depending on the type of equipment and the conditions of the well.

2. Overshot Engagement: Once the milling is complete, an overshot is lowered downhole. The overshot is a specialized tool designed to grab and lift the milled section of the equipment. The overshot is typically equipped with a set of jaws that can be opened and closed to engage with the milled section.

3. Retrieval: Once the overshot has successfully engaged with the milled section, the wireline is used to lift the stuck equipment out of the well. The retrieval process may involve several stages, depending on the depth of the stuck equipment and the complexity of the operation.

Variations in Burn Over Techniques

Several variations of the burn over technique exist, depending on the specific situation:

• Full-length milling: In this method, the entire length of the stuck equipment is milled. This is typically used when the equipment is completely stuck or there is a significant risk of damaging the wellbore if the equipment is not fully milled.
• Partial milling: This method involves milling only a portion of the stuck equipment. This is typically used when the equipment is only partially stuck or when there is a risk of damaging the wellbore if the entire length of the equipment is milled.
• Directional milling: This technique uses a milling tool that can be directed to a specific point in the wellbore. This is particularly useful when the stuck equipment is located in a challenging location, such as a horizontal well.

Challenges and Considerations

Performing a burn over operation is not without its challenges:

• Wellbore damage: There is always a risk of damaging the wellbore during the milling process. This can lead to further complications and additional expenses.
• Stuck equipment: The stuck equipment may be difficult to mill, especially if it is tightly lodged in the wellbore. This can require specialized tools and techniques.
• Wellbore conditions: The conditions of the wellbore, such as the presence of gas or oil, can make it difficult to perform a burn over operation.
• Time and cost: Burn over operations can be time-consuming and expensive. It is important to weigh the costs and benefits before undertaking this procedure.

Chapter 2: Models

Understanding the Physics and Mechanics of a Burn Over

The burn over process relies on a combination of mechanical principles and physical properties of the materials involved:

• Stress Concentration: The milling process creates a weakened area in the stuck equipment, concentrating the stress at the point of separation. This allows the stuck equipment to be more easily removed.
• Shear Force: The overshot's jaws exert a shear force on the weakened area, causing the stuck equipment to separate from the remaining drill string.
• Friction: The friction between the stuck equipment and the wellbore plays a significant role in the difficulty of the burn over. The milling process aims to reduce this friction by creating a smoother surface.

Mathematical Models and Simulations

While not commonly used for routine burn over operations, mathematical models and simulations can be valuable for:

• Predicting the effectiveness of different milling tools and overshots.
• Optimizing the milling process to minimize wellbore damage.
• Analyzing the forces involved in the retrieval process.

These models can help engineers better understand the mechanics of the burn over and make more informed decisions about the best approach for a particular situation.

Chapter 3: Software

Specialized Software for Burn Over Operations

Various software tools are available to assist in planning, executing, and analyzing burn over operations:

• Wellbore modeling software: This software allows engineers to create detailed models of the wellbore, including the location of the stuck equipment, the wellbore geometry, and the properties of the surrounding formations.
• Milling simulation software: This software can simulate the milling process, allowing engineers to evaluate the effectiveness of different milling tools and optimize the milling parameters.
• Overshot selection software: This software helps engineers choose the most appropriate overshot for a specific situation, based on the size and type of stuck equipment and the wellbore conditions.
• Data analysis software: This software allows engineers to analyze the data collected during the burn over operation, helping them to identify potential problems and optimize future operations.

Open-Source Resources and Online Tools

In addition to commercial software, open-source resources and online tools are available for tasks such as:

• Calculating milling rates and forces.
• Estimating the time required for the burn over process.
• Analyzing the stress distribution around the milled area.

These resources can be valuable for engineers who want to perform more detailed calculations or explore different options for their burn over operation.

Chapter 4: Best Practices

Safety First: Minimizing Risks During a Burn Over

Safety is paramount in any oil and gas operation, and burn overs are no exception. Here are some best practices to prioritize safety:

• Thorough planning: Carefully plan the burn over operation, including the specific tools, techniques, and safety procedures.
• Qualified personnel: Ensure that only experienced and qualified personnel operate the equipment and perform the procedure.
• Proper training: Provide comprehensive training to all personnel involved in the burn over operation.
• Emergency preparedness: Develop a detailed emergency response plan and ensure that all personnel are familiar with it.
• Use appropriate safety equipment: Utilize personal protective equipment (PPE), such as hard hats, safety glasses, and gloves, and ensure the proper functioning of all safety systems.

Optimizing the Burn Over Process for Efficiency

Beyond safety, effective planning and execution are crucial for a successful burn over operation:

• Choose the right tools: Select milling tools and overshots appropriate for the type of stuck equipment, wellbore conditions, and depth of the operation.
• Monitor the milling process: Continuously monitor the milling process to ensure that it is proceeding as planned and that there are no signs of wellbore damage.
• Control the rate of penetration: Adjust the milling rate to avoid excessive stress on the stuck equipment and prevent potential wellbore damage.
• Communicate effectively: Maintain clear communication between all personnel involved in the burn over operation.
• Document the process: Thoroughly document every step of the burn over operation, including the tools used, the milling parameters, and any issues encountered.

Chapter 5: Case Studies

Real-World Examples of Successful Burn Over Operations

Examining case studies provides valuable insights into the real-world applications of burn over techniques:

• Recovering a Stuck Drill String in a Deepwater Well: A successful burn over operation involving a stuck drill string in a deepwater well. This case study highlights the challenges of performing burn overs in difficult environments and the importance of careful planning and execution.
• Recovering a Stuck Tubing String in a Horizontal Well: A burn over operation to recover a stuck tubing string in a horizontal well. This case study demonstrates the use of specialized directional milling tools and techniques to address challenging wellbore geometries.
• Minimizing Wellbore Damage During a Burn Over: A case study that emphasizes the importance of minimizing wellbore damage during the burn over operation. This includes using appropriate milling tools, controlling the rate of penetration, and monitoring the wellbore conditions.

Analyzing Failures and Lessons Learned

Examining case studies of unsuccessful burn over operations provides valuable lessons for future operations:

• Incorrect tool selection: Case studies of unsuccessful burn over operations due to the selection of inappropriate tools. These cases highlight the importance of considering the specific circumstances of the operation and choosing the right tools for the job.
• Insufficient planning and execution: Case studies of unsuccessful burn over operations caused by insufficient planning and poor execution. These cases underscore the importance of thorough planning, clear communication, and effective coordination among all personnel involved.
• Wellbore damage: Case studies of unsuccessful burn over operations leading to wellbore damage. These cases emphasize the need to carefully monitor the milling process, control the rate of penetration, and take measures to minimize the risk of wellbore damage.

By examining real-world examples, engineers can learn from both successes and failures, improving their understanding of burn over techniques and developing more effective strategies for future operations.