Build Angle

Understanding Build Angle in Deviated Wells: Navigating the Kickoff Section

In the world of oil and gas exploration, drilling straight down is often not the most efficient way to reach the target reservoir. This is where deviated wells come into play, allowing us to access challenging formations by angling the wellbore. A key concept in deviated well planning is the build angle, which plays a crucial role in the kickoff section, the initial portion of the well where the deviation from vertical begins.

What is Build Angle?

Build angle refers to the angle of inclination of the wellbore from the vertical. It's essentially the rate at which the well is being deviated, measured in degrees. This angle is crucial in determining the trajectory of the wellbore and achieving the desired target location.

The Importance of the Kickoff Section:

The kickoff section, where the well starts to deviate, is of paramount importance because it sets the stage for the entire well trajectory. The build angle in this section determines:

• The curvature of the wellbore: A higher build angle results in a tighter bend, while a lower angle creates a more gradual curve.
• The length of the kickoff section: A higher build angle requires a shorter kickoff section to reach the target inclination.
• The stress and strain on the drillstring: A steeper build angle puts greater stress on the drillstring, requiring careful planning and management.

Factors Affecting Build Angle Selection:

The optimal build angle depends on several factors, including:

• Target depth and location: Deeper targets often require steeper build angles to reach them within a reasonable distance.
• Geological formations: The presence of challenging formations, like faults or fractures, might necessitate a lower build angle to avoid potential risks.
• Drilling equipment and technology: Advanced drilling technology allows for higher build angles and more complex well trajectories.
• Wellbore stability: A lower build angle can help maintain wellbore stability, reducing the risk of borehole collapse.

Understanding Build Angle in the Context of Hold:

"Hold" refers to a period in the drilling process where the wellbore remains at a constant inclination and azimuth. The build angle, therefore, is crucial in determining the duration and length of the hold section. A steeper build angle will require a shorter hold section before the wellbore reaches the desired inclination.

Conclusion:

Build angle is a crucial parameter in deviated well planning, influencing the entire well trajectory and impacting drilling operations. Understanding the role of build angle in the kickoff section, particularly in the context of "hold," is vital for achieving safe and efficient drilling operations while accessing challenging subsurface formations. By carefully selecting the build angle and considering all relevant factors, engineers can ensure a successful and profitable well.