Vertical Well

What Is a Vertical Well?

A vertical well is a hole drilled into the ground, roughly straight down, to reach an underground rock layer that holds oil or natural gas. It is the traditional way of producing hydrocarbons and remains common today. Investors in energy companies often see the term in operating reports, where producers break out drilling activity and production by well type.

How a Vertical Well Works

Drilling starts at the surface with a rig that bores down through successive layers of rock. Steel casing and cement are placed along the hole to protect it and keep fluids separated. Once the drill reaches the target formation, the well is completed: the casing is perforated at the reservoir so hydrocarbons can flow up to the surface. Because the wellbore passes through only a narrow vertical slice of the reservoir, it contacts a relatively limited area of rock. Engineers may use hydraulic fracturing to open tight rock and improve flow, though vertical wells are often used in conventional reservoirs where oil or gas moves more freely.

Vertical Versus Horizontal Wells

• Reservoir contact: a vertical well touches a thin vertical section of the formation, while a horizontal well runs sideways through the layer for a much longer distance.
• Typical use: vertical wells suit thick, conventional reservoirs, while horizontal wells are widely used in shale formations.
• Cost and complexity: vertical wells are generally simpler to drill, while horizontal wells require steerable drilling equipment and usually cost more per well.

Why It Matters to Investors

Production per well influences a producer's revenue, and the mix of vertical and horizontal wells affects how fast output declines and how much capital a company must spend to maintain production. Investors often compare proved reserves and production decline rate figures across companies. Vertical wells usually have lower upfront drilling costs, but they may recover less per well than a horizontal well in the same field. Overall economics depend on local geology, commodity prices, and lease operating expenses. A company's well count alone does not show how profitable its drilling is.