Offshore Drilling Units allow drilling for oil underwater.
Early patents describe over-water drilling wells that never worked. Thomas Rowland filed an 1869 patent for a “submarine drilling apparatus.” There are limited records showing submerged oil wells in 1891, in Grand Lake in Ohio.
However, it wasn’t until 1894 that offshore exploration started in earnest. Henry Williams started exploring for oil around the Santa Barbara coastline. Early wells were promising but Williams theorized more oil is offshore. In 1896, he built a long pier and mounted an oil pump on top, the first offshore drilling unit. The well was productive and soon almost two dozen oil companies were pumping for oil off 14 piers along the California coast.
By 1911, Gulf Refining Company switched from piers to tugboats and barges in Louisiana. When they found a productive well, they’d build a floating platform anchored to the underlying seabed. Water Pyron noticed bubbles in a Texas lake. He and his associates realized the bubbles were flammable. In 1911, they drilled to a depth of 2,185 feet (666 meters) and struck oil. Their well produced 450 barrels of oil per day.
Offshore production stalled during WWI as the country focused on the war effort. However, by 1938 Pure Oil and Superior Oil built freestanding drilling platforms in the Gulf of Mexico, predecessors of the modern rig. The oil field contained four million barrels. In 1947, Kerr-McGee built a platform 10 miles (16 km.) out to sea. Despite the distance, the sea was only 20 feet (6 meters) deep. That well produced 40 barrels per hour, setting off a boom of offshore drilling.
Ever larger rigs were built in ever deeper water. The thirst for oil was unquenchable. However, the rigs are dangerous and there have been a relatively large number of fatalities. Additionally, offshore rigs can cause catastrophic environmental damage. The BP Deepwater Horizon oil spill leaked 4.9 million barrels of oil, polluting hundreds of miles of otherwise pristine coastline. Among other sea-life, infant dolphin deaths increased six-fold. As of 2019, the spill cost BP $65 billion USD.