Most modern oil wells are a few thousand to a few tens of thousands of feet deep, but the very deepest can reach more than 7 miles (over 11 km) into the Earth.

Quick Scoop

Typical depths

  • Many oil reservoirs are found roughly 1,000–20,000 feet below the surface, depending on the geology of the basin.
  • In practice, a lot of producing wells on land fall in the range of about 5,000–10,000 feet deep.
  • Historical data show that in the mid‑20th century, average wells were around 3,600 feet deep, but over the decades the averages have moved closer to 6,000 feet as easier, shallow oil was developed first.

Onshore vs offshore

  • Onshore (land) wells in the U.S. commonly sit around 6,000–10,000 feet deep, with many big fields (like parts of Texas) often exceeding 10,000 feet where the rocks and reservoirs are thicker and more complex.
  • Offshore “shallow water” wells frequently go 10,000–15,000 feet below the seafloor, while deep‑water and ultra‑deep‑water projects can drill 20,000–40,000+ feet beneath the ocean bottom to reach target reservoirs.

Extreme record‑setting wells

  • Some famous wells push the limits: for example, a Gulf of Mexico well associated with the Deepwater Horizon project reached around 35,000 feet below the surface, combining water depth and drilling below the seabed.
  • The Sakhalin‑I project in Russia has drilled extended‑reach wells with measured lengths over 40,000 feet (about 7.7 miles), making them among the deepest and longest oil wells ever drilled.
  • These extreme wells are outliers; most oil production still comes from much shallower depths in comparison.

Why wells go that deep

  • Oil forms in deeply buried sedimentary rocks, so drillers must drill down to where temperature, pressure, and rock type were right to create and trap oil in porous layers called reservoirs.
  • As shallower, easier‑to‑reach resources are produced, companies explore deeper and more technically challenging zones, using advanced drilling technology and stronger equipment to manage very high pressures and temperatures.

Simple way to picture it

  • Think of a “typical” land well as roughly 1–2 miles deep, an offshore deep‑water well as 3–5 miles from the sea surface to the reservoir, and the deepest record‑setting wells as reaching more than 7 miles in measured length.

Information gathered from public forums or data available on the internet and portrayed here.