Offshore Drilling

=Overview=

Offshore wells are drilled in much the same way as their onshore counterparts—with several allowances for the offshore environment, such as a subsea drilling template which allows for accurate drilling while allowing for movement of the drilling platform.

There are two basic types of offshore drilling rigs: those that can be moved from place to place, allowing for drilling in multiple locations, and those rigs that are permanently placed. Moveable rigs are often used for exploratory purposes because they are much cheaper to use than permanent platforms. Once large deposits of hydrocarbons have been found, a permanent platform is built to allow their extraction. In addition to the drilling template, a blowout preventer is installed on the sea floor. This system, much the same as that used in onshore drilling, prevents any oil or gas from seeping out into the water.

New depth records for drilling reached 7,625 feet in the Gulf of Mexico, and Shell Oil's platform "Troll", which stands in the North Sea in 1,000 feet of water, 1,500 feet high, became one of two man-made objects visible with the naked eye from the surface of the moon.

A report by the National Research Council found that offshore oil and gas drilling was responsible for just 2% of the petroleum spilled in North America's oceans, compared with 63% from natural seepage and 22% from municipal and industrial waste. Coast Guard reports show that the amount of oil spilled in U.S. waters dropped from 3.6 million barrels in the 1970s to less than 500,000 in the 1990s.

The offshore oil industry was the focus of much attention following the Deepwater Horizon rig explosion in April 2010 which killed 11 people and unleashed the largest offshore oil spill in U.S. history. In its wake, the US federal authorities clamped down on offshore oil activity, instituting a six-month moratorium on deep-water drilling.

=History=

In the late 19th century, after drilling a large number of wells, early oilmen noticed that those nearest the ocean were the best producers. However, the executor and the date of the first offshore rig is contested, with some sources naming T.F. Rowland as the inventor of offshore drilling as he was the owner of a patent for his offshore drilling rig design in 1869 and others citing H.L. Williams as the executor of the first offshore drilling well in 1887, in Summerland, California. Williams' first well extended about 300 feet into the Pacific ocean. USA Today puts the date of the first U.S. offshore oil production as 1896, also in California.

The first offshore well out of sight of land was completed in 1947 off the coast of the Gulf of Mexico by the Kerr-McGee Corporation, and marked the beginning of the modern offshore industry as it is known today. By 1949, 11 offshore fields were found in the Gulf of Mexico with 44 exploratory wells.

The Second World War also sparked technological progress with regards to the offshore oil industry after its conclusion, including the work of the US Army’s oceanography and weather service, which created a corps of well-trained specialists who forecast wind, wave, and soil conditions. In addition, it sparked improvements in communications which could be adapted for use offshore, as well as vessels designed for the war which could be purchased at low prices after the war.

=Worldwide Operations=

The offshore industry was key to Brazil's energy reserves, with the the 2007 discovery of the Tupi field some 200 miles (320 kilometers) south of Rio de Janeiro in the Atlantic Ocean. According to energy consultants IHS-CERA, Brazil has nearly 48 billion barrels of oil in water of depths of 2,000 feet or greater.

In Africa, the two biggest offshore layers have been Angola and Nigeria. New offshore producers include Ghana with the Jubilee field, Sierra Leone, and Liberia.

While the Gulf of Mexico has been producing offshore for many years, IHS CERA say that the Gulf still holds nearly 13 billion barrels of recoverable deepwater oil.

As of February 2012, there were 113 mobile offshore drilling units in the Gulf of Mexico region, 118 in the Europe/Mediterranean Sea region, 72 units in offshore West Africa, and 121 in the Middle East offshore market.

=Opposition and Controversy=

The debate about offshore drilling stems from questions over how much oil potentially could be recovered from underwater fields versus the time and cost, both in dollars and environmental impact, related to that process.

The prospect of offshore drilling in the Arctic has been a source of controversy despite the fact that the oil is believed to lie less than 500 meters below the surface of the ocean. However, environmentalists say weather conditions would make it difficult to respond in the event of an oil spill, and say the potential results of an oil spill make the risks of drilling for offshore oil unfeasible. Despite this, Norway has been carrying out Arctic exploration.

In Brazil, Margot Stiles, a marine scientist with the conservation organization Oceana, said research funded by Petrobras has helped to discover the deep-sea corals and other ecological treasures in Brazil's offshore drilling region. But she fears the company's operations could put that ocean environment in jeopardy.

"We've been working to limit offshore oil drilling because we just don't see that it's safe," she said. "After the Gulf oil spill people definitely have a greater appreciation for the limits of deep sea drilling technology, and the limits of what we can do to keep things safe."

Environmental groups say that pollution from offshore rigs causes a wide range of health and reproductive problems for fish and other marine life and exposes wildlife to the threat of oil spills that would devastate their populations.

= References =