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Deepwater drilling, [1] or deep well drilling, [2] is the process of creating holes in the Earth's crust using a drilling rig for oil extraction under the deep sea. There are approximately 3400 deepwater wells in the Gulf of Mexico with depths greater than 150 meters. [3] [full citation needed]
The earliest record of well drilling dates from 347 AD in China. [1] Petroleum was used in ancient China for "lighting, as a lubricant for cart axles and the bearings of water-powered drop hammers, as a source of carbon for inksticks, and as a medical remedy for sores on humans and mange in animals."
Well documented examples are the Rota-sludge, Baptist and some variants of the EMAS drilling methods. Perhaps the simplest and cheapest of them all is the Baptist well drilling method, which uses lightweight and cheap PVC pipe for most of the drill stem and in which the drill bit doubles as a foot valve. Wells over 100 metres deep have been ...
K.S. Tom describes the drilling process: "The Chinese method of deep drilling was accomplished by a team of men jumping on and off a beam to impact the drilling bit while the boring tool was rotated by buffalo and oxen." [4] This was the same method used for extracting petroleum in California during the 1860s (i.e. "kicking her down").
Gas lift well: gas is fed into valves installed in mandrels in the tubing strip. The hydrostatic head is lowered and the fluid is gas lifted to the surface. Single-well alternate completions: in this instance there is a well with two zones. In order to produce from both the zones are isolated with packers.
[4] [5] During drilling operations, complex accidents such as gas invasion and overflow are prone to occur. [6] In addition, deep strata have poor diagenesis, weak pressure bearing capacity, so leakage is easy to happen, the risk of well control is high, and the treatment is difficult, which impact on deepwater wellbore integrity seriously.
Casing that is cemented in place aids the drilling process in several ways: [2] Prevents contamination of fresh water well zones. Prevents unstable upper formations from caving in and sticking the drill string or forming large caverns. Provides a strong upper foundation to allow use of high-density drilling fluid to continue drilling deeper.
The oil well is created by drilling a long hole into the earth with an oil rig. A steel pipe (casing) is placed in the hole, to provide structural integrity to the newly drilled well bore. Holes are then made in the base of the well to enable oil to pass into the bore.