The biggest oil rigs are more than drilling sites. They may combine wells, processing equipment, power generation, compressors, utilities, accommodation, and safety systems. Some stand on the seabed; others float in water thousands of meters deep.
But which is the biggest oil rig in the world? There is no single answer. Offshore facilities can be compared by weight, height, water depth, deck area, or processing capacity. These six examples show why the record changes with the measurement—and how cooling systems keep them operating.
What Counts as the Biggest Oil Rig?
“Oil rig” is often used broadly, although engineers distinguish drilling rigs from production platforms and floating production units. The largest oil platform by mass is not necessarily the tallest or the one operating in the deepest water.
This is therefore not a strict ranking. Each installation represents a different measure of scale. Production figures refer to design or processing capacities, not current daily output, which changes during a field’s life.
Six of the Biggest Oil Rigs in the World
Hibernia
Located about 315 kilometers southeast of Newfoundland, Hibernia is a gravity-based platform built for the North Atlantic. Its completed structure was 224 meters high and weighed almost 600,000 tonnes at mating. Guinness World Records recognizes it as the heaviest offshore oil platform. Its concrete base provides oil storage and resists sea ice and iceberg impacts.
Berkut
Berkut stands off Russia’s Sakhalin coast in the Sea of Okhotsk. It is known for its massive topside and subarctic design. The platform must withstand sea ice, severe waves, earthquakes, and temperatures approaching −44°C. Here, “biggest” refers to the scale and weight of the operating modules rather than water depth.
Petronius
Petronius is a compliant tower in the Gulf of Mexico. Extending roughly 600 meters from the seabed, depending on the measurement point, it is among the tallest freestanding offshore structures. Its slender tower moves with waves and wind. This flexibility allows a tall structure to operate without a proportionally massive rigid jacket.
Perdido
Shell’s Perdido hub is a spar platform moored in approximately 2,450 meters of water. A deep cylindrical hull provides stability, while mooring lines secure it to the seabed. Designed to handle about 100,000 barrels of oil and 200 million cubic feet of gas per day, Perdido shows how operating depth can define the scale of a floating oil rig.
Olympus (Mars B)
Olympus, also called Mars B, is a tension-leg platform in the Gulf of Mexico. Vertical tendons connect its floating hull to the seabed and limit its motion. Its design capacity exceeds 100,000 barrels of oil equivalent per day. Olympus represents the deck space and processing capability achievable with a large tension-leg platform, not an absolute weight record.
Stones FPSO
Stones is an FPSO development operating in roughly 2,900 meters of water. Its vessel-shaped facility receives hydrocarbons from subsea wells, processes them, stores oil, and transfers it to shuttle tankers. Stones shows how major processing functions can be placed on a floating vessel in ultra-deep water.
How Offshore Oil Rigs Work
Offshore wells are drilled through the seabed into reservoirs. After completion, oil, gas, water, and sediment flow toward the surface. Platform equipment separates the stream, treats the hydrocarbons, manages produced water, and prepares the output for pipeline transport or offshore transfer.
Oil platform parts may include compressors, pumps, engines, generators, cranes, hydraulic units, control rooms, fire protection, and living quarters. A large platform therefore operates like a compact industrial plant, not a simple drilling tower.
Why Some Oil Rigs Float: Main Offshore Platform Types
Do oil rigs float? Some do, and some do not. Fixed jackets and gravity-based structures rest on or attach to the seabed. Jack-up rigs lower legs to the seabed and raise their hull above the water for drilling. Compliant towers remain bottom-founded but flex under environmental loads.
In deeper water, semi-submersible rigs, spar platforms, tension-leg platforms, drillships, and FPSOs float. Mooring systems, vertical tendons, ballast, or dynamic positioning keep them in the required location. The appropriate platform type depends on water depth, seabed conditions, field life, well layout, processing needs, and expected weather.
How Offshore Oil Rigs Stay Cool
Large platforms generate heat continuously. Engines and generators require jacket-water and lubricating-oil cooling. Compressors may need interstage and aftercooling. Hydraulic power units, bearings, electrical equipment, and process systems also depend on controlled temperatures.
Many installations use closed freshwater or treated-water loops to collect heat. It can then be rejected through seawater-cooled shell-and-tube heat exchangers or, where the layout permits, air-cooled heat exchangers. Separating machinery from seawater helps protect it, but places demanding corrosion, fouling, and material requirements on the exchanger.
Offshore cooling equipment must also fit restricted spaces and tolerate vibration, platform movement, salt-laden air, and limited maintenance access. Engineers therefore evaluate heat duty, fluid composition, inlet and outlet temperatures, pressure, allowable pressure drop, metallurgy, inspection requirements, and cleaning access together. A compact unit is not useful if it cannot be serviced safely or maintain its thermal performance.
Need a Custom Heat Exchanger for Offshore Equipment?
JED manufactures custom shell-and-tube heat exchangers, air-cooled heat exchangers, and oil coolers for demanding industrial and marine equipment. We can manufacture from customer drawings or review operating data with your engineering team.
Send us the cooling medium, flow rate, temperatures, pressure, allowable pressure drop, material requirements, installation limits, and applicable inspection or testing requirements. Our team can review new equipment and replacement-cooler inquiries without assuming that one standard design fits every offshore duty.
Frequently Asked Questions
Do all offshore oil rigs store the oil they produce?
No. FPSOs and some gravity-based platforms have oil-storage capacity, while many fixed and floating production platforms send treated hydrocarbons to shore or another facility through pipelines.
How do workers and supplies reach large offshore oil rigs?
Crews commonly travel by helicopter or crew-transfer vessel. Food, fuel, spare parts, and heavy equipment are delivered by offshore supply vessels according to the platform’s location and operating conditions.
How many people work on the biggest oil rigs?
Crew size varies widely. A large production platform may accommodate more than 100 people, but automation, maintenance activity, drilling campaigns, and whether accommodation is located on the same structure all affect the number.
What happens when an offshore oil platform reaches the end of its service life?
The operator must follow the applicable decommissioning plan. Wells are permanently plugged, hydrocarbons and waste are removed, and platform components may be dismantled, transported to shore, reused, or recycled under regulatory requirements.
