Drilling & Well Completion

Departure

Departure: Navigating the Oil & Gas Well Path

In the world of oil and gas exploration, precise terminology is crucial for effective communication and efficient operations. One such term is Departure, which plays a vital role in understanding the well's trajectory and guiding drilling decisions.

Departure refers to the horizontal distance travelled by the drill bit from the kelly bushing to the end of the well. It's essentially the projection of the wellbore onto the horizontal plane, representing the lateral movement of the drill bit.

Understanding Departure:

  • Kelly Bushing: The top of the drill string, situated at the surface, serves as the reference point for measuring Departure.
  • Horizontal Distance: This measurement is crucial for determining the well's reach and understanding its positioning relative to target formations or existing wells.
  • End of the Well: This can refer to the current position of the drill bit or the planned target depth, depending on the context.

Importance of Departure:

  • Well Planning: Departure plays a key role in well planning, helping engineers determine the optimal trajectory to reach target formations while avoiding obstacles like existing wells or sensitive environmental areas.
  • Directional Drilling: Departure is a critical parameter in directional drilling, where wells are intentionally deviated from a vertical path.
  • Reservoir Management: Understanding the well's Departure helps optimize reservoir production by ensuring the wellbore intersects the target zone at the desired location.

Departure in Different Drilling Techniques:

  • Vertical Wells: Departure is minimal in vertical wells, as the drill bit travels straight down.
  • Horizontal Wells: Departure is significant in horizontal wells, where the drill bit is intentionally deviated to create a long horizontal section within the reservoir.
  • Directional Wells: Departure varies depending on the angle of deviation, allowing for controlled well path adjustments to optimize production.

Measuring Departure:

Departure is typically measured using survey data obtained during the drilling process. This data is used to calculate the wellbore trajectory, including the horizontal distance from the kelly bushing.

Conclusion:

Departure is an essential parameter in oil and gas well planning and operations. It provides valuable information about the well's horizontal position, enabling engineers to make informed decisions regarding well trajectory, reservoir management, and overall drilling efficiency. As the industry continues to advance towards more complex drilling techniques, understanding Departure remains crucial for navigating the intricate world of subsurface exploration.

Test Your Knowledge

Quiz: Departure in Oil & Gas Well Path

Instructions: Choose the best answer for each question.

1. What does "Departure" refer to in oil and gas well drilling?

a) The total depth of the wellbore. b) The vertical distance traveled by the drill bit. c) The horizontal distance traveled by the drill bit. d) The angle of deviation from vertical.

Answer

c) The horizontal distance traveled by the drill bit.

2. From which point is Departure measured?

a) The bottom of the wellbore. b) The target formation. c) The kelly bushing. d) The drill bit.

Answer

c) The kelly bushing.

3. In which type of well is Departure typically the most significant?

a) Vertical well. b) Horizontal well. c) Directional well. d) All types of wells have similar Departure.

Answer

b) Horizontal well.

4. Why is Departure important in well planning?

a) To calculate the drilling time. b) To determine the well's trajectory and reach. c) To estimate the amount of oil and gas in the reservoir. d) To predict the formation pressure.

Answer

b) To determine the well's trajectory and reach.

5. How is Departure typically measured?

a) By using a depth gauge. b) By using a pressure sensor. c) By using survey data obtained during drilling. d) By using a GPS system.

Answer

c) By using survey data obtained during drilling.

Exercise:

Scenario:

You are planning a new horizontal well. The target formation is located 2,000 meters below the surface and 1,000 meters horizontally from the drilling location.

Task:

  1. Calculate the Departure of the well.
  2. Based on the Departure and target depth, describe the trajectory of the well (e.g., vertical, horizontal, angled).

Exercice Correction

1. **Departure:** The Departure in this case is the horizontal distance from the drilling location to the target formation, which is **1,000 meters**. 2. **Trajectory:** The well will start vertically down for a certain distance (2,000 meters) to reach the target depth and then deviate horizontally for 1,000 meters to reach the target formation. Therefore, the trajectory of the well is **angled**, transitioning from vertical to horizontal.

Books

  • Petroleum Engineering: Drilling and Well Completion by John Lee (This textbook covers well planning and trajectory, including concepts like departure.)
  • Drilling Engineering: Principles and Applications by Robert M. Edwards and Michael J. Mayerhofer (This book provides a comprehensive understanding of drilling operations and principles, including directional drilling techniques and well trajectory analysis.)
  • Wellbore Positioning: Principles and Applications by John A. Holmes (This book focuses on the specific aspects of wellbore positioning, including calculations and considerations related to departure.)

Articles

  • "Directional Drilling: A Review of the Fundamentals and Advancements" by A.K. Sharma and S.K. Sharma (This article covers the history and advancements of directional drilling, providing insights into the role of departure in this technique.)
  • "Wellbore Trajectory Design and Optimization" by S.A. Holditch and J.A. Holmes (This article explores the concepts and techniques used in designing and optimizing well trajectories, highlighting the significance of departure in well planning.)

Online Resources

  • SPE (Society of Petroleum Engineers) Digital Library: This platform offers a vast collection of technical papers and articles covering various aspects of oil and gas engineering, including well planning and trajectory. Search keywords like "departure", "wellbore trajectory", and "directional drilling" for relevant resources.
  • OnePetro: This online database provides access to technical publications and data from various oil and gas industry sources, including SPE, AAPG (American Association of Petroleum Geologists), and other relevant organizations. Search keywords related to "departure" and well path analysis for relevant information.
  • "Understanding Wellbore Trajectory" by Schlumberger: This online resource from Schlumberger, a leading oilfield services company, offers a concise explanation of wellbore trajectory concepts, including departure and its relevance in well planning and operations.

Search Tips

  • Use specific keywords like "departure wellbore trajectory", "horizontal distance well path", and "directional drilling departure calculation" for more targeted search results.
  • Combine keywords with relevant industry terms like "oil and gas", "drilling", "well planning", and "reservoir management".
  • Use quotation marks around specific phrases to find exact matches, such as "departure in horizontal wells".
  • Refine your search results by specifying the publication year or type of document (e.g., PDF, articles, etc.).

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