Offshore Wells

Leakage from offshore oil wells is responsible for only about 2% of the oil in the sea (Figure 6-2). Thus it is surprising that there is always major opposition from local communities when it is proposed to drill for oil along the East or West coasts of the United States. This mind-set is probably due to the images of the well that "blew" off Santa Barbara, California, in January 1969. This oil was pressurized by methane gas in the ground, and the pressure forced out the oil when the well was drilled. The high pressure forced oil out of the seafloor in the vicinity of the well and thus the flow could not be stopped by capping the well. It was necessary to drill additional wells to dissipate the gas pressure so that the oil flow could be controlled. Other examples include the North Sea blowout in 1977 and the Ixtoc 1 well, which continued for almost a year (from June 1979 to the spring of 1980) in the Gulf of Mexico off the coast of Campeche, close to the Yucatan Peninsula. The latter well spewed out 140 million gallons of crude oil (Figure 6-3). Now, however, unless the oil is pressurized, potential "blowout" sites can be identified by geologists, so the danger of major leaks from offshore oil wells appears to be minimal. There are 6000 wells off the coasts of Texas and Louisiana with no reports of major spills. One study has concluded that drilling offshore wells results in less environmental risk than transporting the oil in large tankers from the Gulf of Mexico or the Middle East because of the problems with tanker use discussed in Section 6.3.5.1

1W. B. Travers and P. R. Luney, Science 194, 791-796 (1976).

Oil Spill Colour Sunglasseshttp://www.nwn.noaa. gov/sites/hazmat/photos/ships/08.html. Also see color insert."/>
FIGURE 6-3 The Ixtoc exploratory well, which blew out and caught fire June 3, 1979. It spilled 140 million gallons of oil into the Gulf of Mexico. From http://www.nwn.noaa. gov/sites/hazmat/photos/ships/08.html. Also see color insert.
0 0

Post a comment