What Is Directional Drilling?

Directional Drilling involves techniques used to control the direction and deviation of the drilling process to reach a specific subsurface target. This entry discusses its definition, history, techniques, applications, and related terms.

Directional drilling involves the application of various techniques to control the direction and deviation of the drilling process to reach a specific subsurface target. This technique is essential for efficiently accessing resources such as oil, gas, and geothermal energy that are not vertically aligned with the wellbore.

Techniques Used in Directional Drilling

Mud Motors and Rotary Steerable Systems (RSS)

Mud motors and RSS are essential for directional drilling, providing control over the wellbore’s direction without the need to stop drilling.

• Mud Motors: These use the force of drilling mud to turn a drill bit.
• Rotary Steerable Systems: These allow for continuous rotation of the drill string while steering the bit direction.

Measurement While Drilling (MWD)

MWD provides real-time data on the wellbore’s inclination and azimuth.

• Inclination: The angle of the wellbore relative to the vertical.
• Azimuth: The compass direction of the wellbore trajectory.

Historical Context

Directional drilling dates back to the early 20th century but gained prominence during the 1920s when the need to reach reservoirs located beneath obstacles such as cities or water bodies became apparent.

• Early Innovations: The first significant directional wells were drilled in the 1930s in the Long Beach Harbor area of California to access oil beneath the sea.
• Technological Advancements: Over the decades, advances in MWD and RSS have significantly enhanced the precision and efficiency of directional drilling.

Applications of Directional Drilling

Oil and Gas Industry

Directional drilling is widely used to reach reservoirs that are not vertically aligned with the drilling site.

• Horizontal Drilling: Involves drilling horizontally to increase the interface with the oil or gas-bearing formation.
• Extended Reach Drilling: Extends the reach of the wellbore horizontally to access distant subsurface targets.

Geothermal Energy

Directional drilling helps in creating effective geothermal wells to tap into geothermal reservoirs that are not directly beneath the drilling site.

Environmental Applications

This technique is also used for environmental purposes, such as installing horizontal wells for soil remediation or groundwater treatment.

Comparisons and Related Terms

• Vertical Drilling: Involves drilling a well straight down. It is simpler but less effective for accessing certain types of resources.
• Horizontal Drilling: A subtype of directional drilling where the wellbore is drilled horizontally to maximize contact with the resource layer.
• Slant Drilling: Another form of directional drilling where the well is drilled at an angle other than vertical.

FAQs

What are the main advantages of directional drilling?

Directional drilling allows access to resources in locations that would be otherwise inaccessible, increases the efficiency of resource extraction, and minimizes surface disturbance by allowing multiple wells to be drilled from a single site.

How do mud motors work in directional drilling?

Mud motors use the force of circulating drilling mud to power a turbine that turns the drill bit, thus steering the wellbore in the desired direction.

What role does MWD play in directional drilling?

MWD provides real-time data on the wellbore’s orientation and helps in making on-the-fly adjustments to the drilling direction.

References

1. Mitchell, R.F., & Miska, S. (2011). Fundamentals of Drilling Engineering. Society of Petroleum Engineers.
2. Bourgoyne, A.T., et al. (1986). Applied Drilling Engineering. Society of Petroleum Engineers.
3. “Directional Drilling Explained: What is it & How Does it Work?” Energy Education. Retrieved from energyeducation.ca.

Summary

Directional drilling is a crucial technique in resource extraction, enabling access to subsurface targets through controlled deviation and precise steering of the wellbore. With applications spanning across the oil and gas industry, geothermal energy, and environmental management, this technology continues to evolve, significantly impacting modern engineering and resource management.