Visualizing Environmental Science

Oil and Natural Gas 425

Double-hulled

tanker

Insulated

storage

tanks

Reserves of Oil and

Natural Gas

Oil and natural gas deposits exist on

every continent, but their distribution

is uneven. More than half of the world’s

total estimated reserves are situated in the

Persian Gulf region, which includes Iran,

Iraq, Kuwait, Oman, Qatar, Saudi Arabia, Syria,

the United Arab Emirates, and Yemen. Major oil

fields also exist in Venezuela, Mexico, Russia, Kazakhstan,

Libya, and the United States (in Alaska and the Gulf of

Mexico; ˆ}ÕÀiʣǰ£ä).

Almost half of the world’s proved recoverable re-

serves of natural gas are located in two countries, Russia

and Iran. The United States has more deposits of natural

gas than western Europe.

Large oil deposits probably exist under the conti-

nental shelves, the relatively flat underwater areas that

surround continents, and in deep-water areas adjacent

to the continental shelves. Despite problems such as

storms at sea and the potential for oil spills, many coun-

tries engage in offshore drilling. As many as 18 billion

barrels (756 billion gals) of oil and natural gas may ex-

ist in the deep water of the Gulf of Mexico, just off the

continental shelf from Texas to Alabama. Continental

shelves off the coasts of western Africa and Brazil are

also promising potential sources of oil. Environmental-

ists and coastal industries such as fishing generally op-

pose opening the continental shelves for oil and natural

gas exploration because of the threat of a major oil spill.

must first be compressed to form liquefied natural gas
(LNG) and then carried on specially constructed re-
frigerated ships (ˆ}ÕÀiʣǰ™). After LNG arrives at its
destination, it must be returned to the gaseous state at
regasification plants before being piped to where it will
be used. Currently, the United States has only four such
plants, which severely restricts the importation of natural
gas from other countries. American energy companies
claim that the United States needs at least 40 regasifi-
cation plants to keep costs down for natural gas and to
meet increasing demands.

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Tanker ships transport liquified natural
gas in large, cylindrical tanks.