IN PURSUIT OF PETROLEUM
IN PURSUIT OF PETROLEUM
The hunt for oil and natural gas uses tried-and-true
principles of petroleum accumulation combined with
the latest state-of-the-art tools.
Back in the earliest days of oil exploration, people looked for petroleum by drilling
along creeks, on top of oil seeps, and on surface domes and structures. Most times, luck
was more of a factor in their success than skill. The science of petroleum exploration devel-oped
along with the industry. Today, the easy oil and gas has already been found, and the
hunt for hydrocarbons is an extremely sophisti-cated, highly technical effort.
Oil and gas are now sought in many remote locations around the globe: in water more than
10,000 feet deep in the Gulf of Mexico, the deserts of Egypt and China, the mountainous
western Canada and Colombia, the islands of Indonesia, and the swamps along the coasts of
Louisiana and Nigeria’s Niger Delta. Nevertheless, the fundamentals of geology
remain unchanged. Oil and gas are found in sedimentary rocks, which cover about 75% of
the earth’s land area. About 700 sedimentary basins dot the world; about half of these have
been explored for oil and gas. Limestones, dolomites, sandstones, shales and siltstones are
the hunting grounds for petroleum geologists. It is within these layered rocks that the ex-plorer
searches for the four elements necessary for a petroleum accumulation: source, reservoir,
trap and seal. Petroleum source rocks are often thick, black marine shales laid down in ancient
seas. As soon as a plant or animal dies, bacteria attack its remains. If oxygen is plentiful, as in
soil, bacteria will consume all the organic mat-ter. But in very fine-grained muds deposited on
the sea floor, oxygen is limited and much of the organic matter escapes destruction. As these
muds are buried by successive layers of sedi-ment, rising heat “cooks” the organic matter,
throwing off water, carbon dioxide and hydro-carbons. Generating crude oil from organic matter in
source rocks is a slow process, requiring mil-lions of years. Temperatures must be just per-fect—
oil can only be formed between 120 and 350 degrees Fahrenheit, temperatures found at
burial depths between 5,000 and 21,000 feet. If the source rocks get any hotter, natural gas and
graphite are formed instead. Reservoir rocks are hosts for hydrocarbons.
The hunt for oil and natural gas uses tried-and-true
principles of petroleum accumulation combined with
the latest state-of-the-art tools.
Back in the earliest days of oil exploration, people looked for petroleum by drilling
along creeks, on top of oil seeps, and on surface domes and structures. Most times, luck
was more of a factor in their success than skill. The science of petroleum exploration devel-oped
along with the industry. Today, the easy oil and gas has already been found, and the
hunt for hydrocarbons is an extremely sophisti-cated, highly technical effort.
Oil and gas are now sought in many remote locations around the globe: in water more than
10,000 feet deep in the Gulf of Mexico, the deserts of Egypt and China, the mountainous
western Canada and Colombia, the islands of Indonesia, and the swamps along the coasts of
Louisiana and Nigeria’s Niger Delta. Nevertheless, the fundamentals of geology
remain unchanged. Oil and gas are found in sedimentary rocks, which cover about 75% of
the earth’s land area. About 700 sedimentary basins dot the world; about half of these have
been explored for oil and gas. Limestones, dolomites, sandstones, shales and siltstones are
the hunting grounds for petroleum geologists. It is within these layered rocks that the ex-plorer
searches for the four elements necessary for a petroleum accumulation: source, reservoir,
trap and seal. Petroleum source rocks are often thick, black marine shales laid down in ancient
seas. As soon as a plant or animal dies, bacteria attack its remains. If oxygen is plentiful, as in
soil, bacteria will consume all the organic mat-ter. But in very fine-grained muds deposited on
the sea floor, oxygen is limited and much of the organic matter escapes destruction. As these
muds are buried by successive layers of sedi-ment, rising heat “cooks” the organic matter,
throwing off water, carbon dioxide and hydro-carbons. Generating crude oil from organic matter in
source rocks is a slow process, requiring mil-lions of years. Temperatures must be just per-fect—
oil can only be formed between 120 and 350 degrees Fahrenheit, temperatures found at
burial depths between 5,000 and 21,000 feet. If the source rocks get any hotter, natural gas and
graphite are formed instead. Reservoir rocks are hosts for hydrocarbons.
posted by Yoda at
10:02 AM
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