When the first offshore well was drilled off Summerland, California, in 1896, it was hard to imagine where the industry would end up. The early setup was modest: a wooden rig built on a pier, only a few feet above the water, using cable-tool methods similar to onshore drilling. Operators ventured only slightly offshore to reach shallow reservoirs.
More than a century later, offshore operations have pushed into territory that would have sounded impossible to those first drillers. Some modern wells extend beyond 12,000 metres in total measured depth, while drilling takes place in water depths measured in thousands of metres. Platforms, once simple timber structures, have become vast industrial machines—massive, tall, and capable of producing hundreds of thousands of barrels per day. Floating facilities such as Prelude FLNG operate like offshore processing plants, hosting large crews and handling gas processing at sea.
These milestones are not just “records.” They reflect the engineering creativity required to operate at the edge of what’s feasible. Below is a guided look at some of the most widely cited deepest offshore wells and largest offshore platforms, illustrating the scale and ambition of the sector.
The world’s deepest offshore wells (selected record-holders)
Offshore drilling has long been a race for depth and reach. As easy reservoirs were depleted, operators moved farther offshore and drilled deeper beneath the seabed. Directional and extended-reach drilling made it possible to access targets far from the surface location—sometimes without adding more platforms.
Al Shaheen, BD-04A (Qatar)
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Total measured depth: ~40,320 ft (≈12,290 m)
Drilled in 2008, BD-04A became a benchmark for long extended-reach wells. Its horizontal section was driven through a very thin productive interval to tap dispersed reservoirs beneath thick overburden.
Odoptu OP-11 (Sakhalin, Russia)
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Total measured depth: 40,502 ft (≈12,345 m)
In 2011, Odoptu OP-11 pushed extended-reach drilling further, highlighting how far operators could “reach” into offshore reservoirs from fixed infrastructure—despite subarctic operating challenges.
Z-44 Chayvo (Sakhalin, Russia)
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Total measured depth: ~40,602 ft (≈12,376 m)
Often cited among the deepest and most ambitious extended-reach wells, Z-44 (2012) required precision drilling in harsh, icy conditions and helped reduce the need for additional offshore platforms.
Tiber (Gulf of Mexico, USA)
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Vertical depth: ~35,050 ft (≈10,683 m)
Before the Deepwater Horizon disaster made the name infamous, the rig drilled the Tiber exploration well (2009), setting major vertical-depth benchmarks and underscoring the extreme pressures and complex geology in ultra-deep prospects.
Ondjaba-1 (Angola)
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Water depth: ~11,903 ft (≈3,628 m)
Drilled in 2021, Ondjaba-1 is widely referenced for record-setting water depth, demonstrating what dynamically positioned drillships can achieve far beyond the continental shelf.
The largest offshore platforms and “engineering giants”
Modern offshore platforms are more than production sites—they’re semi-autonomous industrial hubs with accommodation, power generation, processing, storage, and weather/ice survival design. Some weigh hundreds of thousands to over a million tonnes, rivaling the size and complexity of major onshore facilities.
Prelude FLNG (Australia)
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Length: 1,601 ft (≈488 m)
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Displacement (fully loaded): ~600,000 tonnes
A floating LNG facility designed to produce, process, and liquefy natural gas directly at sea—essentially a floating gas plant.
Hibernia (Canada)
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Height: 735 ft (≈224 m)
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Weight (with ballast): ~1.2 million tonnes
A gravity-based structure engineered for iceberg impacts in the North Atlantic, with substantial storage and long-term production capability.
Troll A (Norway, North Sea)
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Height: 1,549 ft (≈472 m)
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Weight (with ballast): ~1.2 million tonnes
Often described as the tallest structure ever moved by humans, anchored by enormous concrete legs extending deep below the surface.
Gullfaks C (Norway, North Sea)
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Height: 1,247 ft (≈380 m)
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Weight: ~420,000 tonnes
A classic heavy gravity-based platform built for harsh North Sea operations, notable for its massive scale and long service life.
Petronius (USA, Gulf of Mexico)
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Height: 2,100 ft (≈640 m)
A compliant-tower design that flexes with currents—well suited to deepwater areas exposed to powerful storms.
Thunder Horse PDQ (USA, Gulf of Mexico)
A major production-drilling platform designed for extreme hurricane conditions and deepwater operations, often cited among the largest semi-submersible PDQ units.
Perdido Spar (USA, Gulf of Mexico)
A deepwater spar platform known for record-setting operating depth in its class, using a large cylindrical hull for stability.
Olympus TLP (USA, Gulf of Mexico)
A tension-leg platform designed to access deeper reservoirs and extend field life for decades.
Berkut (Russia, Sea of Okhotsk)
A harsh-environment, ice-resistant platform built for subarctic conditions, designed to handle extreme cold, heavy seas, and ice loads.
Pushing limits also raises the stakes
From extended-reach wells like Z-44 Chayvo to giant platforms like Troll A and Petronius, offshore engineering keeps expanding what’s possible. But deeper wells and larger structures come with tougher operating envelopes: higher pressures and temperatures, tighter safety margins, harsher weather, and more complex operations.
The next frontier isn’t just drilling deeper or building bigger—it’s ensuring that safety, reliability, and risk management scale faster than the records do.
