Vertical Well

Vertical Well: Definition, How It Works, and Uses

What is a vertical well?

A vertical well is a borehole drilled straight down from the surface to access an underground oil or natural gas reservoir located directly beneath the well site. It is the traditional method of hydrocarbon extraction and contrasts with directional or horizontal drilling, which steers the borehole at an angle or horizontally through the reservoir.

Key takeaways

• Vertical wells are simple and cost-effective for reserves located directly below the drill site.
• They are less efficient for laterally extensive reservoirs, where directional or horizontal drilling is usually more productive.
• Vertical wells remain essential as the starting point for directional drilling and are still widely used in offshore operations.

How vertical wells work

A vertical well drills a straight borehole from the surface down into the target reservoir. Advantages include:
* Simpler equipment and operations, which can lower capital and labor costs.
* Faster drilling times for targets directly beneath the site.
* Reliable subsurface sampling: cuttings and core samples from different depths help locate and characterize reservoirs.

Limitations arise when the hydrocarbon-bearing formation extends horizontally over a wide area. To access such reserves efficiently, companies often use directional drilling to create horizontal laterals from an initial vertical wellbore, allowing extraction from a larger portion of the reservoir with fewer surface locations.

Vertical vs. horizontal wells

Definition: A horizontal well is produced by steering the borehole at an angle (generally at least 80 degrees from vertical) to run parallel to the reservoir, increasing contact with productive rock.
Trends: Horizontal drilling grew rapidly and surpassed vertical drilling in the late 2010s. By the end of 2018 in U.S. shale plays, horizontal drilling accounted for the vast majority of crude oil and natural gas production. Despite this shift, many vertical wells remain active.

Practical uses and examples

• Exploration and evaluation: Vertical wells are routinely drilled to collect rock samples at various depths. These data guide reservoir mapping and decisions about where and how to place laterals.
• Foundation for directional drilling: All directional and horizontal wells typically begin with a vertical pilot hole. From that base, drillers steer into the reservoir to extend the well laterally.
• Multi-reservoir access: When conditions allow, companies can use a single vertical well as the launching point for multiple directional laterals, enabling production from several distinct reservoirs and reducing surface footprint and infrastructure.
• Offshore drilling: Vertical wells are commonly used on offshore platforms because drilling from fixed marine structures is complex and offshore directional operations are often more costly.

When to choose a vertical well

Use a vertical well when:
* The reservoir lies directly beneath the surface location.
* Simplicity, lower upfront cost, and faster deployment are priorities.
* The project is exploratory or intended to collect subsurface data.
* Offshore conditions or economics make directional drilling impractical.

Conclusion

Vertical wells remain a fundamental component of oil and gas development. Their straightforward design makes them suitable for direct, localized targets and as the necessary starting point for directional and horizontal drilling strategies that maximize recovery from laterally extensive formations.