Concentric Completion

Test Your Knowledge

Concentric Completion Quiz:

Instructions: Choose the best answer for each question.

1. What is the primary benefit of using a concentric completion? a) Increased production from both zones. b) Reduced drilling and completion costs. c) Minimized environmental impact. d) All of the above.

2. Where does the gas from the upper zone flow in a concentric completion? a) Through the tubing. b) Through the casing. c) Through the annulus. d) Through a separate pipeline.

3. What type of gas reservoir is typically suitable for the upper zone in a concentric completion? a) Wet gas. b) Sour gas. c) Sweet, dry gas. d) Condensate gas.

4. Why is a pressure differential important for effective gas flow in a concentric completion? a) To prevent the upper zone gas from entering the production zone. b) To ensure proper separation of the gas streams at the surface. c) To maintain a consistent flow rate from both zones. d) All of the above.

5. Which of the following is NOT a consideration for using a concentric completion? a) The type of gas in the upper zone. b) The pressure differential between the zones. c) The depth of the well. d) The presence of corrosive components in the gas.

Concentric Completion Exercise:

Scenario: An oil and gas company has identified a sweet, dry gas reservoir at a depth of 2,000 meters and a deeper oil reservoir at a depth of 3,500 meters. They are considering a concentric completion to produce both reservoirs simultaneously.

Task:

• List the potential benefits of using a concentric completion in this scenario.
• Identify any potential challenges or considerations that the company should address before implementing this method.
• Suggest possible solutions for the identified challenges.

Techniques

Chapter 1: Techniques

Concentric Completion: A Targeted Approach to Gas Production

Concentric completion is a well completion technique designed for efficient gas production from multiple zones, particularly when a shallower, sweet, dry gas reservoir lies above a deeper production zone. It involves utilizing the annulus between the casing and tubing in a wellbore to channel gas from the upper zone to the surface, while production from the deeper zone occurs through the tubing.

How it Works

• Upper Zone: Gas from the upper zone flows upward through the annulus.
• Production Zone: Gas from the deeper zone flows upward through the tubing.
• Surface Separation: At the surface, the two gas streams are separated, allowing for individual processing and marketing.

Key Elements

• Casing: Provides structural support and seals off different zones.
• Tubing: Transports gas from the deeper production zone to the surface.
• Annulus: The space between the casing and tubing, used to channel gas from the upper zone.
• Annulus Control: Management of the annulus pressure to prevent gas from the upper zone entering the production zone.
• Surface Separation Equipment: Separates the two gas streams for individual processing.

Variations

• Single Annulus Completion: A single annulus is used to produce from both zones.
• Dual Annulus Completion: Two separate annuli are used, allowing for independent control of each zone.
• Selective Completion: Allows for isolating or activating individual zones using valves and other equipment.

Chapter 2: Models

Understanding the Flow Dynamics

Concentric completion involves complex flow dynamics. Several models can help predict and optimize gas production from both zones:

• Multiphase Flow Models: Account for the flow of gas, water, and oil in both the annulus and tubing.
• Pressure-Transient Analysis: Used to assess reservoir pressure and estimate production rates.
• Flow Simulation Software: Simulates the flow of gas in the wellbore, predicting production rates and optimizing well performance.

Considerations for Model Selection

• Reservoir Characteristics: Including permeability, porosity, and pressure.
• Wellbore Geometry: Including casing and tubing sizes.
• Production Rate: The desired production rate from each zone.
• Annulus Pressure Management: Predicting pressure differentials and potential risks of cross-flow.

Model Limitations

• Assumptions and Simplifications: Models rely on assumptions that may not fully capture the complexity of the real-world scenario.
• Data Availability: Accurate model predictions require accurate and complete data about the reservoir, wellbore, and production parameters.

Chapter 3: Software

Available Tools

• Well Completion Design Software: Facilitates well completion design, including concentric completion configurations.
• Reservoir Simulation Software: Simulates reservoir behavior, including fluid flow and pressure changes, for optimizing concentric completion strategies.
• Production Optimization Software: Analyzes production data and provides insights for optimizing well performance, including annulus pressure management.

Software Features

• Flow Simulation: Simulates the flow of gas in the wellbore, predicting production rates and optimizing well performance.
• Pressure-Transient Analysis: Evaluates pressure changes and estimates reservoir properties.
• Wellbore Design: Provides tools for designing wellbore configurations, including concentric completion elements.
• Data Management: Manages and analyzes well production data, enabling performance tracking and optimization.

Choosing the Right Software

• Specific Project Needs: Select software that aligns with the specific requirements of the project.
• Data Integration: Ensure the software can integrate with existing databases and data sources.
• User Interface and Functionality: Choose user-friendly software that meets the technical skillset of the team.

Chapter 4: Best Practices

Planning and Design

• Thorough Reservoir Evaluation: Understanding the reservoir characteristics and pressure profiles is crucial for effective concentric completion design.
• Wellbore Design Optimization: Careful selection of casing, tubing, and other equipment sizes based on flow rates and pressure differentials.
• Annulus Control Strategies: Implementing procedures and equipment for managing annulus pressure and preventing cross-flow.

Installation and Completion

• Quality Control: Ensure proper installation and completion of the concentric completion to minimize risks and maximize performance.
• Safety Precautions: Implement safety protocols and procedures during well installation and operation to protect personnel and the environment.
• Testing and Monitoring: Conduct thorough testing after installation to validate the system's functionality and ensure desired production rates.

Operation and Maintenance

• Annulus Pressure Monitoring: Regularly monitor annulus pressure to identify potential issues and prevent cross-flow.
• Production Optimization: Continuously analyze production data to identify opportunities for improving well performance.
• Regular Maintenance: Schedule regular maintenance of the well equipment to ensure its continued reliability and safety.

Chapter 5: Case Studies

Case Study 1: Enhanced Production in a Tight Gas Reservoir

• Challenge: A tight gas reservoir with low permeability and high pressure required an efficient production strategy.
• Solution: Concentric completion was implemented to produce gas from a shallower, sweet, dry gas zone, supplementing the production from the deeper tight gas zone.
• Results: Significant improvement in production rates, enhancing profitability and sustainability.

Case Study 2: Minimizing Environmental Impact in a Challenging Environment

• Challenge: Producing gas from a deep reservoir in a sensitive ecological area required a solution with minimal environmental impact.
• Solution: Concentric completion allowed for producing gas from a shallow gas zone, reducing the number of wells and surface infrastructure required.
• Results: Reduced environmental footprint, minimizing the disturbance to the surrounding ecosystem.

Case Study 3: Cost-Effective Production from Multiple Zones

• Challenge: Producing gas from two separate zones required a cost-effective solution without sacrificing production.
• Solution: Concentric completion combined the production from both zones through a single wellbore, reducing drilling and completion costs.
• Results: Improved cost-effectiveness, allowing for a profitable development of multiple zones with minimal capital investment.

Conclusion

Concentric completion offers a targeted and efficient approach to gas production from multiple zones. This technique provides benefits such as enhanced production, cost-effectiveness, reduced environmental impact, and improved safety. As the oil and gas industry continues to focus on sustainability and optimization, concentric completion proves to be a valuable tool for maximizing production while minimizing environmental impact.