Offshore Drilling
Offshore drilling can be traced as far as 1869, when a patent for the blueprint of an offshore drilling rig was approved forT.F. Rowland. Though Rowland’s rig was intended to function in shallow water, the anchored four legged tower is comparable to that of contemporary offshore oil rigs. After World War II, the first offshore oil well that was totally out of land’s view was drilled in 1947 in the Gulf of Mexico. Offshore oil wells are charged with the responsibility of extracting crude oil from reserves within the bed of lakes and the floor of oceans. Ever since that time, offshore oil generation and particularly in the Gulf of Mexico, which is still a major offshore oil site, has thrived with the detection and distribution of multiple oil and gas deposits. Oil wells off the Barents Sea’s northeast coast supply nearly 90% of Australia’s total petroleum. Offshore oil rigs make up 25% of natural gas reserves and 24% of oil manufacture in the United States. Over the last several years, almost 100 wells a year on average have been discovered in the Barents Sea. On the other hand, the established Campos Basin comprises 80% of Brazil's oil manufacture. Offshore oil drilling offers a wide array of oil rig job opportunities including driller, shakerhand, toolpusher, floormen, ballast controlman, barge engineer or rig welder. World-wide, there are 971 offshore oil rigs including 676 mobile rigs and 295 permanent platforms.
There are two main types of offshore drilling rigs: movable rigs which permit drilling in multiple places, and permanent platforms. Frequently, moveable oil rigs are used to search for hydrocarbon deposits and are much cheaper than permanent ones. After discovering large deposits of hydrocarbons, a permanent platform is built to draw them out. Offshore drilling, sometimes hundreds of miles away from shore, is very different from land-based drilling. However, the drilling tool used to physically dig into the ocean floor is very similar to that used on a land-based oil rig; except that obviously, the sea floor is thousands of feet below. It is because of this extraordinary distance between the rig and the ocean floor that a man-made drilling platform must be built, whereas the ground provides a natural platform during land-based drilling. Man-made platforms vary in composition and appearance, based upon the necessities of the well being drilled and how far down the oil goal is.
In offshore oil drilling, a blowout preventer is also mounted on the sea floor. The blowout preventer is like that of one used in land-based drilling, which prevents oil or gas from leaking into the water. A marine riser connects the blowout preventer down on the sea floor to the drilling platform above. The marine riser is intended to accommodate the drill bit and drillstring, while remaining supple enough to handle the shifts of the drilling platform. Slip and ball joints tactically placed within the marine riser enable the undersea well to remain unaffected by drilling platform’s movement.
Another vital piece of offshore drilling equipment is the undersea drilling template, which bonds the underwater well site to the drilling platform on the water’s surface. The drilling template looks similar to a cookie cutter and is comprised of an open steel container with the number of its holes reliant upon the quantity of wells to be drilled. The drilling template is positioned above the well site, typically lowered into the desired spot with the aid of satellite and GPS equipment. Then the drilling template is cemented within a comparatively shallow hollowed out hole. After being anchored to the ocean floor and connected with cables to the drilling platform above, the drilling template enables precise drilling to occur, while also permitting the motion of the above drilling platform, which is invariably influenced by irregular wind and water currents.
Additional Information
- Offshore oil rigs can take anytime from 2 to 4 years to make
- The type and size of offshore oil rig determines the amount of workers needed to operate
- Most rigs are able to operate 24/7
- A shallow offshore oil rig can cost from 75 to 175 million US dollars
- A deep offshore oil rig can cost from 100 to 400 million US dollars
- A drillship can cost from 300 to 500 million US dollars for a new one