Drilling & Well Completion

Workover

Workover: The Art of Reviving Dormant Wells

In the dynamic world of oil and gas exploration, wells are not static entities. Over time, production rates can decline, equipment can malfunction, or the well itself may encounter unforeseen problems. This is where workover comes into play.

What is a Workover?

Simply put, a workover is a procedure designed to repair, maintain, or enhance the production of an existing well. It involves various operations aimed at restoring or improving the well's performance.

Why is a Workover Necessary?

  • Production Decline: As a well ages, its natural reservoir pressure can decrease, leading to a drop in oil or gas production. Workovers can help stimulate production by techniques like acidizing or fracturing.
  • Equipment Failure: Components like tubing, packers, or downhole pumps can fail, requiring replacement or repair.
  • Wellbore Issues: Problems like sand production, water influx, or corrosion can compromise the well's integrity and necessitate workover operations.
  • Production Optimization: Workovers can also be used to optimize production by implementing technologies like downhole artificial lift systems or advanced completion techniques.

Typical Workover Operations:

  • Well Killing: This involves removing pressure from the well by circulating fluid until the well is deemed safe to work on.
  • Tubing String Operations: The existing tubing string may be pulled out, inspected, repaired, or replaced with a new one.
  • Downhole Equipment Installation or Repair: Installing, repairing, or replacing downhole components like packers, pumps, or valves.
  • Well Stimulation: Techniques like acidizing or fracturing can be employed to increase reservoir productivity.
  • Well Testing: Testing is conducted to evaluate the well's performance after the workover.

Types of Workovers:

  • Minor Workovers: These are typically less complex and involve repairs or maintenance that can be done with minimal downtime.
  • Major Workovers: These involve more extensive repairs, requiring more significant equipment and expertise.
  • Stimulation Workovers: Focus on enhancing production through techniques like acidizing or fracturing.
  • Recompletion Workovers: Involve changing the completion design of the well to improve production or target different zones.

Rig Types:

While workovers are often performed on conventional drilling rigs, other platforms are used depending on the complexity of the operation.

  • Workover Rigs: These are specially designed for workover operations and are typically smaller and more mobile than drilling rigs.
  • Coiled Tubing Units: These units use a coiled tubing string to perform workover operations and are particularly useful for complex wellbore interventions.

Conclusion:

Workovers are an essential part of maximizing the economic life of oil and gas wells. By addressing operational issues and improving production, workovers play a vital role in sustaining profitability and optimizing resource recovery in the industry.


Test Your Knowledge

Workover Quiz:

Instructions: Choose the best answer for each question.

1. What is the primary purpose of a workover?

a) To explore for new oil and gas reserves. b) To drill a new well. c) To repair, maintain, or enhance the production of an existing well. d) To transport oil and gas to refineries.

Answer

c) To repair, maintain, or enhance the production of an existing well.

2. Which of these is NOT a common reason for performing a workover?

a) Production decline. b) Equipment failure. c) Wellbore issues. d) Discovering new oil and gas deposits.

Answer

d) Discovering new oil and gas deposits.

3. Which of the following is a common workover operation?

a) Building a new pipeline. b) Well killing. c) Designing a new drilling rig. d) Obtaining permits for exploration.

Answer

b) Well killing.

4. What type of workover focuses primarily on increasing production using techniques like acidizing or fracturing?

a) Minor workover. b) Stimulation workover. c) Recompletion workover. d) Major workover.

Answer

b) Stimulation workover.

5. What is a coiled tubing unit used for?

a) Transporting oil and gas to refineries. b) Drilling new wells. c) Performing workover operations with a flexible tubing string. d) Storing drilling fluids.

Answer

c) Performing workover operations with a flexible tubing string.

Workover Exercise:

Scenario: A well has experienced a significant drop in production due to a buildup of paraffin wax in the wellbore.

Task: Propose a workover plan to address this issue and restore production. Consider the following:

  • Typical workover operations: What specific operations would be necessary to remove the paraffin?
  • Equipment: What equipment would be required for this workover?
  • Safety considerations: What safety precautions need to be taken during the workover?
  • Potential challenges: What challenges might arise during the workover process?

Exercice Correction

**Workover Plan:** **Operations:** * **Well Killing:** To safely remove pressure from the well before working on it. * **Tubing String Operations:** The tubing string may need to be pulled out to access the paraffin buildup. * **Paraffin Removal:** This can be done through various methods, including: * **Mechanical Removal:** Using tools like scrapers or brushes to physically remove the paraffin. * **Chemical Treatment:** Injecting solvents or chemicals to dissolve the paraffin. * **Heating:** Using hot oil or steam to melt the paraffin and allow it to flow. * **Well Testing:** To evaluate the well's performance after the paraffin removal. **Equipment:** * Workover rig or coiled tubing unit. * Tubing string handling equipment. * Paraffin removal tools (scrapers, brushes, etc.) or chemical injection equipment. * Heating equipment (if necessary). **Safety Considerations:** * Ensure proper safety procedures for well killing and working on pressurized systems. * Use personal protective equipment (PPE) during operations. * Ensure proper ventilation during chemical treatment or heating processes. **Potential Challenges:** * Difficulty accessing the paraffin buildup. * Paraffin may be very stubborn and difficult to remove. * Chemical treatments may cause damage to the wellbore. * Heating may cause thermal damage to the wellbore or surrounding formations. **Note:** The specific workover plan will depend on the severity of the paraffin buildup, the well's configuration, and other factors. A thorough evaluation of the situation is essential before implementing any workover plan.


Books

  • "Petroleum Engineering: Drilling and Well Completions" by John A. Lee - A comprehensive text covering drilling and well completion techniques, including workover operations.
  • "Well Workovers: Principles and Practices" by A.C.W. van Oort - Provides a detailed overview of workover operations, encompassing different techniques, equipment, and challenges.
  • "Well Intervention and Workover Engineering" by A.K. Sharma - Covers the technical aspects of well intervention, emphasizing workovers and their importance in well lifecycle management.

Articles

  • "Workover: The Art of Reviving Dormant Wells" by SPE - This article provides an overview of workover operations, covering their types, techniques, and benefits.
  • "The Importance of Workovers in Oil and Gas Production" by Oil & Gas Journal - This article focuses on the significance of workovers in maximizing production and extending the life of wells.
  • "Optimizing Workover Operations for Enhanced Production" by Schlumberger - Discusses advanced techniques and technologies used for improving workover effectiveness and production optimization.

Online Resources

  • SPE (Society of Petroleum Engineers): https://www.spe.org/ - A leading organization for petroleum professionals, offering a vast library of resources, including papers, presentations, and technical guidelines related to workovers.
  • Schlumberger: https://www.slb.com/ - A global oilfield services company, providing information about its workover services and technologies.
  • Halliburton: https://www.halliburton.com/ - Another leading oilfield services company, offering information on its workover services and equipment.
  • Baker Hughes: https://www.bakerhughes.com/ - Provides details on their workover services, technologies, and case studies.

Search Tips

  • Use specific keywords like "workover operations," "well stimulation," "downhole equipment," and "completion techniques" to narrow your search.
  • Include the type of well, like "oil well workover," "gas well workover," or "horizontal well workover."
  • Search for specific workover techniques like "acidizing," "fracturing," or "coiled tubing workover."
  • Add keywords related to specific challenges like "sand production," "water influx," or "corrosion."
  • Combine keywords with phrases like "best practices," "case studies," or "technical guidelines" for more focused results.

Techniques

Similar Terms
Drilling & Well CompletionReservoir Engineering
Most Viewed
Categories

Comments


No Comments
POST COMMENT
captcha
Back