Glossary of Technical Terms Used in Drilling & Well Completion: workover

workover

Revitalizing Oil Wells: The Importance of Workover Operations

In the world of oil and gas production, wells don't always stay productive forever. Over time, factors like declining reservoir pressure, formation damage, and equipment malfunction can lead to reduced output. This is where workover operations come into play, offering a lifeline to rejuvenate aging wells and maximize their potential.

What are Workover Operations?

Workover operations encompass a variety of remedial procedures performed on a producing well to enhance its production. These interventions address specific problems and aim to restore or increase the well's efficiency. Workovers can involve anything from minor repairs to complex well interventions, depending on the nature of the issue.

Common Types of Workover Operations:

  1. Deepening: Extending the wellbore to reach deeper, potentially more productive reservoir zones. This is effective when the original target zone becomes depleted.
  2. Plugging Back: Isolating unproductive sections of the wellbore by placing cement plugs to redirect flow to more productive zones. This is often used when a well encounters water or gas coning.
  3. Pulling and Resetting Liners: Removing and reinstalling well liners to address issues like corrosion, wear, or poor cement bonding. This improves wellbore integrity and prevents fluid leakage.
  4. Squeeze Cementing: Injecting cement slurry into the wellbore to seal off unwanted zones or repair damaged casings. This enhances wellbore integrity and prevents fluid communication between different zones.
  5. Acid Stimulation: Injecting acidic solutions into the formation to dissolve minerals, improve permeability, and enhance oil flow. This is used to address formation damage caused by mineral deposition.
  6. Fracturing: Creating fractures in the formation by injecting high-pressure fluids. This enhances well productivity by increasing the surface area for oil flow.

Benefits of Workover Operations:

  • Increased Production: Workovers can significantly boost well output by addressing production problems and optimizing well performance.
  • Extended Well Life: By addressing issues that hinder production, workovers can extend the lifespan of wells, making them profitable for longer periods.
  • Cost-Effective: Workover operations are generally less expensive than drilling new wells, offering a cost-effective way to maintain and enhance production.
  • Environmental Sustainability: Workovers help maximize production from existing wells, reducing the need for drilling new wells and minimizing environmental impact.

Reconnection to the Big Picture:

Workover operations are an essential component of oil and gas production management, contributing to overall well optimization and sustainable resource extraction. These interventions are essential to maximize production from existing wells, minimizing the need for new drilling and contributing to a more environmentally responsible approach to resource utilization. By effectively addressing well issues and enhancing their performance, workover operations play a vital role in ensuring the long-term profitability and sustainability of oil and gas operations.


Test Your Knowledge

Quiz: Revitalizing Oil Wells: The Importance of Workover Operations

Instructions: Choose the best answer for each question.

1. What is the primary purpose of workover operations?

a) To explore new oil and gas reserves. b) To enhance the production of existing wells. c) To dismantle and dispose of old oil wells. d) To prevent oil spills and environmental damage.

Answer

b) To enhance the production of existing wells.

2. Which of the following is NOT a common type of workover operation?

a) Deepening b) Plugging Back c) Acid Stimulation d) Fracking e) Drilling New Wells

Answer

e) Drilling New Wells

3. What is the main benefit of "plugging back" a well?

a) Increasing the well's depth to reach new reserves. b) Sealing off unproductive sections to improve flow to productive zones. c) Injecting acid to dissolve minerals and improve permeability. d) Creating fractures in the formation to enhance oil flow.

Answer

b) Sealing off unproductive sections to improve flow to productive zones.

4. How do workover operations contribute to environmental sustainability?

a) By reducing the need to drill new wells. b) By preventing oil spills and leaks. c) By promoting cleaner energy sources. d) By reusing old well equipment.

Answer

a) By reducing the need to drill new wells.

5. Which of the following is NOT a benefit of workover operations?

a) Increased Production b) Extended Well Life c) Reduced Exploration Costs d) Cost-Effectiveness

Answer

c) Reduced Exploration Costs

Exercise: Workover Operations Case Study

Scenario: An oil well has been experiencing declining production over the past few years. Initial investigations reveal that the well is producing water alongside oil, and the reservoir pressure is low.

Task:

  1. Identify at least two possible workover operations that could address the issues in this well.
  2. Explain how these operations would help revitalize the well and improve production.
  3. Briefly discuss the potential benefits and drawbacks of each operation in this scenario.

Exercice Correction

**Possible Workover Operations:** 1. **Plugging Back:** This operation would involve isolating the water-producing zone by placing a cement plug. This would direct the flow of oil to the remaining productive zones and prevent further water production. * **Benefits:** Improved oil flow, reduced water production, potentially increased reservoir pressure. * **Drawbacks:** May result in a decrease in overall production if the plugged zone was still contributing some oil. 2. **Acid Stimulation:** This operation would involve injecting acidic solutions into the formation to dissolve minerals that are clogging the pores, improving permeability, and boosting oil flow. * **Benefits:** Increased oil production, improved reservoir pressure, potentially reduced water production. * **Drawbacks:** Requires careful monitoring to avoid damage to the formation, may not be effective if the water production is due to a high water table. **Explanation:** Both plugging back and acid stimulation could address the issues of water production and low reservoir pressure. Plugging back would physically isolate the water zone, while acid stimulation would enhance the flow of oil through the formation, potentially increasing pressure. **Overall, the choice between these operations would depend on the specific geological conditions and the desired outcome.**


Books

  • Petroleum Production Engineering by M. Muskat (A classic and comprehensive text covering various aspects of oil production, including workovers)
  • Well Workover Handbook by R.E. Anderson (Provides detailed guidance on planning, executing, and troubleshooting various workover operations)
  • Modern Well Stimulation: Design, Evaluation, and Interpretation by G.L. King (Focuses on well stimulation techniques, including acidizing and fracturing, used in workover operations)
  • Drilling Engineering: A Practical Approach by G.P. Demaison (Covers aspects of drilling and well completion, which are closely related to workover operations)

Articles

  • Workover Optimization: A Key to Maximizing Production from Mature Fields by J.D. Graham (Discusses strategies for optimizing workover operations to enhance production from mature fields)
  • Understanding and Managing Wellbore Integrity in Workover Operations by T.J. Smith (Highlights the importance of wellbore integrity during workover procedures)
  • The Impact of Formation Damage on Workover Operations by M.A. Aasen (Explains how formation damage can affect well productivity and how workovers can address it)
  • A Review of Workover Technologies and Their Application in the Oil and Gas Industry by R.J. Brown (Provides a comprehensive overview of different workover technologies and their applications)

Online Resources

  • Society of Petroleum Engineers (SPE) - SPE offers numerous publications, articles, and technical papers on workover operations, as well as online forums for discussion.
  • American Petroleum Institute (API) - API publishes standards and guidelines related to oil and gas operations, including those relevant to workover operations.
  • International Association of Drilling Contractors (IADC) - IADC provides resources and information on drilling and workover practices.
  • Oil & Gas Journal - This journal regularly publishes articles and technical updates on workover operations and other oil and gas industry topics.

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