Reservoir Engineering

Heel

Heel: The Pay Zone Closest to the Casing in a Deviated Well

In the world of oil and gas exploration, "heel" refers to a specific geological feature relevant to highly deviated wells. It signifies the area of the pay zone that is closest to the well's casing.

Understanding the "Heel"

Imagine drilling a well that's not straight down, but instead, curves significantly, reaching its target reservoir at an angle. This is a deviated well, often employed to access reservoirs that are difficult to reach with traditional vertical drilling.

The heel is essentially the point where the wellbore first enters the pay zone. Because the wellbore is angled, the heel is located near the casing, which is the protective pipe lining the well. As the wellbore continues its deviated path, it leaves the heel behind and progresses through the pay zone.

Importance of the Heel

The heel plays a significant role in oil and gas production:

  • Reservoir Access: Understanding the heel location is crucial for optimizing production from the well. It allows engineers to accurately predict fluid flow patterns and maximize the well's productivity.
  • Fluid Distribution: The heel is often the first area to experience a decline in reservoir pressure due to its proximity to the wellbore. This affects how fluids (oil, gas, and water) move through the reservoir and impacts production rates.
  • Reservoir Characterization: Studying the production behavior at the heel can provide valuable insights into the reservoir's overall characteristics, such as permeability and porosity. This information helps in optimizing production strategies.
  • Production Optimization: By understanding the heel's dynamics, engineers can adjust production parameters, such as flow rates and wellhead pressure, to optimize oil and gas recovery from the deviated well.

Implications for Drilling and Production

The concept of the heel is particularly important in highly deviated wells because:

  • Increased Complexity: Due to the well's angle, the heel's pressure and flow dynamics are more complex than in vertical wells.
  • Potential for Water Production: The heel is often closer to the water-oil contact (the boundary between the oil zone and the water zone), increasing the risk of water production early in the well's life.
  • Challenges in Production: The heel's proximity to the casing can cause challenges in well completion and production, requiring specialized techniques and equipment.

Conclusion

The "heel" in oil and gas exploration is a critical element in understanding the production behavior of deviated wells. Its location and characteristics significantly impact well productivity, reservoir characterization, and production optimization. By accurately analyzing the heel and understanding its role, engineers can ensure maximum recovery of hydrocarbons from these complex wells.


Test Your Knowledge

Quiz: Understanding the Heel in Deviated Wells

Instructions: Choose the best answer for each question.

1. What is the "heel" in a deviated well?

a) The point where the wellbore first enters the pay zone.

b) The deepest point of the wellbore.

c) The area of the pay zone farthest from the casing.

d) The point where the wellbore transitions from vertical to deviated.

Answer

a) The point where the wellbore first enters the pay zone.

2. Why is the heel important in a deviated well?

a) It determines the well's total length.

b) It helps predict fluid flow patterns and optimize production.

c) It indicates the depth of the reservoir.

d) It helps determine the well's vertical depth.

Answer

b) It helps predict fluid flow patterns and optimize production.

3. Which of the following is NOT a challenge associated with the heel in a deviated well?

a) Increased complexity in well completion.

b) Potential for water production early in the well's life.

c) Difficulty in determining the well's horizontal reach.

d) Challenges in production due to its proximity to the casing.

Answer

c) Difficulty in determining the well's horizontal reach.

4. How does the heel's proximity to the casing affect production?

a) It increases the well's overall productivity.

b) It can lead to premature pressure decline in the reservoir.

c) It makes the well less susceptible to water production.

d) It makes it easier to monitor reservoir pressure.

Answer

b) It can lead to premature pressure decline in the reservoir.

5. What information can be gained by studying the production behavior at the heel?

a) The well's total cost.

b) The reservoir's permeability and porosity.

c) The well's trajectory.

d) The well's vertical depth.

Answer

b) The reservoir's permeability and porosity.

Exercise: Analyzing Heel Dynamics

Scenario: An oil well is drilled with a significant deviation angle. The wellbore first enters the pay zone at a depth of 2,500 meters. The heel is located 100 meters from the casing, and the wellbore continues to deviate further into the reservoir.

Task:

  1. Draw a simple diagram illustrating the wellbore, the heel, and the casing.
  2. Explain how the heel's proximity to the casing might affect production in this scenario.
  3. Discuss potential strategies for optimizing production from this well, considering the heel's dynamics.

Exercise Correction

**1. Diagram:**

The diagram should illustrate a deviated wellbore with the casing extending vertically down. The heel is marked as the point where the wellbore first enters the pay zone, located 100 meters away from the casing. The wellbore then continues its deviated path, moving further away from the casing.

**2. Production Impact:**

The heel's proximity to the casing can cause several issues for production:

  • Pressure Decline: The heel, being closer to the wellbore, will experience faster pressure depletion than other parts of the reservoir. This can impact production rates and potentially lead to premature water production.
  • Fluid Flow Patterns: The angled wellbore and the heel's position can create complex flow patterns, affecting the distribution of oil, gas, and water.
  • Well Completion Challenges: The proximity of the heel to the casing can make well completion operations more challenging, requiring specialized techniques and equipment.

**3. Optimization Strategies:**

Strategies to optimize production from this well, considering the heel's dynamics, could include:

  • Artificial Lift: Using methods like gas lift or electric submersible pumps to maintain pressure in the heel and optimize production.
  • Production Optimization: Adjusting production rates and wellhead pressure to manage pressure drawdown in the heel area.
  • Reservoir Stimulation: Techniques like acidizing or fracturing to enhance reservoir permeability near the heel, improving fluid flow.
  • Monitoring and Analysis: Implementing a comprehensive monitoring system to track pressure changes, fluid production rates, and other parameters to analyze the heel's influence on production.

These strategies should be carefully evaluated and implemented based on the specific reservoir characteristics and well conditions.


Books

  • Reservoir Engineering Handbook by Tarek Ahmed (2018) - This comprehensive handbook covers various aspects of reservoir engineering, including deviated wells and production optimization.
  • Petroleum Engineering: Principles and Practices by John M. Campbell (2016) - This textbook provides a detailed overview of petroleum engineering principles, including drilling, completion, and production.
  • Drilling Engineering by Robert E. Krueger (2008) - Focuses on the engineering aspects of drilling, including wellbore trajectory, directional drilling, and well completion.

Articles

  • "Wellbore Trajectory and Production Optimization in Deviated Wells" by Mohammad Amin Nasseri et al. (2023) - This research article discusses the impact of wellbore trajectory on production performance, particularly focusing on the heel and its implications.
  • "Challenges in Production from Highly Deviated Wells" by Andrew J. Watson et al. (2019) - Examines the specific challenges encountered in producing from deviated wells, including fluid distribution and well completion.
  • "Reservoir Characterization and Production Simulation for Deviated Wells" by David A. Thomas et al. (2018) - This paper explores how reservoir characterization and simulation techniques can be adapted for deviated wells, considering the heel's influence.

Online Resources

  • SPE (Society of Petroleum Engineers): The SPE website offers a wealth of resources, including research papers, technical presentations, and industry events related to drilling and production, including deviated wells. Search for keywords like "heel," "deviated well," "wellbore trajectory," and "production optimization."
  • OnePetro: OnePetro provides access to a vast library of technical articles and papers from various industry sources. Search for relevant keywords related to deviated wells and production optimization.
  • Oil & Gas Journal (OGJ): This industry publication features articles and news related to oil and gas exploration and production. Search for articles discussing deviated well technologies and challenges.

Search Tips

  • Use specific keywords like "heel," "deviated well," "wellbore trajectory," "production optimization," "reservoir characterization," and "water production."
  • Combine keywords with phrases like "oil and gas," "petroleum engineering," "drilling," "completion," and "production."
  • Utilize Boolean operators ("AND", "OR," "NOT") to refine your search. For example, "heel AND deviated wells" or "production optimization NOT vertical wells."
  • Search for PDF documents to find research papers and technical reports.
  • Explore the "Advanced Search" options on Google to further narrow your search by date, language, and file type.

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