How Do Offshore Oil Rigs Work?

May 19, 2025 | Workplace Accidents

How Do Offshore Oil Rigs Work?

Offshore oil rigs are huge structures in the ocean that drill for oil and gas beneath the seafloor. They allow companies to tap into underwater oil reserves that they otherwise couldn’t reach. 

These rigs are a big part of the oil supply. In 2024, about 14% of U.S. crude oil production came from offshore wells in the Gulf of Mexico.

Below is a simple breakdown of the process, the technology behind it, and the risks workers shoulder day in and day out.

What is an Offshore Oil Rig?

An offshore oil rig is a large, self-contained facility for drilling and pumping oil in the ocean. It holds all the drilling equipment, storage tanks, and even living quarters for the crew. 

In shallow water, an oil rig is built on a fixed platform — a structure with long legs anchored into the ocean floor. In deeper water, some rigs float and use anchors or thrusters to hold their position.

How Do Offshore Oil Rigs Drill for Oil?

Once the rig is in position above a suspected underwater oil deposit, a long drill bit attached to a series of pipes (the drill string) bores into the seabed. A large pipe called a “riser” connects the platform to the well and lets workers circulate drilling fluid (mud) down to the drill bit and back up.

Drilling mud cools the drill and carries crushed rock cuttings out while also balancing underground pressure to prevent blowouts. A blowout preventer (BOP) on the seabed can seal the well if a sudden surge of oil or gas occurs, like the one witnessed in the Deepwater Horizon incident.

The crew drills in stages, adding steel casing and cement to reinforce the well as it gets deeper. Eventually, the drill reaches the oil-bearing rock layer, and the well is sealed and prepared for oil extraction.

How Do Offshore Oil Rigs Extract Oil?

Once a well is ready for production, natural pressure in the underground reservoir often pushes oil up on its own. The rig’s valves at the wellhead control the flow and prevent it from gushing out uncontrollably.

Over time, the pressure drops, and oil won’t flow freely. When that happens, crews use pumps or inject water or gas into the well to force more oil out.

The crude oil from the well is mixed with gas and water. The rig separates out water and other impurities and burns off excess gas in a flare (the flame is visible on the platform). Finally, the oil is sent to shore by pipelines or tanker ship for refining.

Life and Safety on the Rigs

Crew members tend to work 12-hour shifts for two to four weeks straight. Tight quarters, heavy machinery, and volatile fluids create constant danger. Even with strict safety protocols, there is always a risk of workplace accidents on a rig. 

Common hazards include:

  • Explosions or fires from oil and gas leaks
  • Falls from high platforms
  • Slippery decks leading to slip and fall accidents
  • Heavy equipment accidents (such as crane failures or dropped objects)
  • Extreme weather and rogue waves

Regulations require fire-resistant clothing, lifeboat drills, and round-the-clock medical staff to mitigate some of these issues.

High-Tech Marvels, High-Stakes Work

Offshore oil rigs are remarkable feats of engineering that allow access to energy resources from beneath the sea. They use massive machines to drill wells and pump oil in places humans could never otherwise reach. At the same time, they remain high-risk environments.

When accidents happen on a rig, the aftermath can be just as devastating as a serious accident on land or even more so. In fact, according to the most recent complete federal data, 78 oil and gas extraction workers died on the job in 2023 (10 in extraction, 13 in drilling, and 55 in support operations).

By understanding how offshore oil rigs work and the risks involved, the public can better appreciate the bravery of the crews and the importance of strong safety measures in these extreme conditions.

If you’ve been injured in a personal injury, please contact Marzzacco Niven & Associates at the nearest location to schedule a free consultation today:

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