Petroleum: A Chemical “Black Gold”
So, what is petroleum and where does it come from? By definition,
petroleum, in the strictest sense of the word, is crude oil as it comes
out of the ground. It is a mixture of several chemical compounds,
primarily hydrogen and carbon. In a broader sense, and for the purposes
of this book, petroleum also is defined as all hydrocarbons,
including oil, natural gas, natural gas liquids, and all related products.
Petroleum also can exist as a solid, such as the tar sands found
in some parts of Canada and the oil shale beds located in some
western states.
Even after two hundred years, the origin of black gold, as it is
sometimes called, remains the subject of debate. Since the midnineteenth
century, scientists have variously believed that petroleum
comes from coal, decayed animals and vegetables, and even
volcanic matter. Today, the debate still continues in some scientific
circles as to whether oil is organic (plant or vegetable matter) or
inorganic (not living).
The general consensus among the majority of the earth’s scientists,
however, is that the petroleum produced today was formed
over a period of millions of years when plant and animal matter was
compressed as it settled at the bottom of prehistoric seabeds. This
matter, covered with layers and layers of sediment, was changed
into hydrocarbons through a combination of factors, including bacteria,
heat, and pressure.
Oil was first believed to flow under the earth much like an
underground stream of water. Further study throughout the years
led scientists to learn that oil actually exists between geological
structures in areas called reservoirs. The Society of Petroleum Engineers
(SPE), one of the industry’s largest professional organizations,
compares a reservoir rock to a tray of marbles, with oil occupying
the open spaces between the grains of rock.
Oil reservoirs may be a few thousand or many thousands of feet
below the surface. How permeable—or how easily the oil or gas
flows through connecting pore spaces—determines how easy it is
to remove the petroleum from the ground. How petroleum is
found and removed from these reservoirs will be discussed later.
Petroleum First Used to Light Fires
Scientists believe that the earliest use of petroleum occurred when
natural seepages of both crude oil and natural gas were used by
primitive tribes to light their fires. According to several versions of
the story of the Great Flood, Noah used pitch—a form of natural
asphaltic petroleum—as a caulking material to waterproof his ark.
Indian tribes are said to have used asphalt from the seeps at Santa
Barbara, California, as a sealant for their canoes, as well as for war
paints and medicines. And archaeologists believe the ancient Egyptians
used the same substance as a lubricant on chariot wheels. The
Greeks are said to have used petroleum to set the sea on fire to
destroy a fleet of ships belonging to an enemy that was threatening
invasion.
It is thought that by the Middle Ages, Sicilians were gathering
oil off their coast to use as fuel for lamps. Europeans, in the meantime,
skimmed the natural springs for oil that they used for medicinal
purposes, as well as for fuel.
It was the Chinese, however, who first drilled for petroleum.
Using primitive drilling tools, they bored eight hundred feet into
the earth in 347 A.D.—fifteen centuries before the birth of the
modern-day petroleum industry!
So, what is petroleum and where does it come from? By definition,
petroleum, in the strictest sense of the word, is crude oil as it comes
out of the ground. It is a mixture of several chemical compounds,
primarily hydrogen and carbon. In a broader sense, and for the purposes
of this book, petroleum also is defined as all hydrocarbons,
including oil, natural gas, natural gas liquids, and all related products.
Petroleum also can exist as a solid, such as the tar sands found
in some parts of Canada and the oil shale beds located in some
western states.
Even after two hundred years, the origin of black gold, as it is
sometimes called, remains the subject of debate. Since the midnineteenth
century, scientists have variously believed that petroleum
comes from coal, decayed animals and vegetables, and even
volcanic matter. Today, the debate still continues in some scientific
circles as to whether oil is organic (plant or vegetable matter) or
inorganic (not living).
The general consensus among the majority of the earth’s scientists,
however, is that the petroleum produced today was formed
over a period of millions of years when plant and animal matter was
compressed as it settled at the bottom of prehistoric seabeds. This
matter, covered with layers and layers of sediment, was changed
into hydrocarbons through a combination of factors, including bacteria,
heat, and pressure.
Oil was first believed to flow under the earth much like an
underground stream of water. Further study throughout the years
led scientists to learn that oil actually exists between geological
structures in areas called reservoirs. The Society of Petroleum Engineers
(SPE), one of the industry’s largest professional organizations,
compares a reservoir rock to a tray of marbles, with oil occupying
the open spaces between the grains of rock.
Oil reservoirs may be a few thousand or many thousands of feet
below the surface. How permeable—or how easily the oil or gas
flows through connecting pore spaces—determines how easy it is
to remove the petroleum from the ground. How petroleum is
found and removed from these reservoirs will be discussed later.
Petroleum First Used to Light Fires
Scientists believe that the earliest use of petroleum occurred when
natural seepages of both crude oil and natural gas were used by
primitive tribes to light their fires. According to several versions of
the story of the Great Flood, Noah used pitch—a form of natural
asphaltic petroleum—as a caulking material to waterproof his ark.
Indian tribes are said to have used asphalt from the seeps at Santa
Barbara, California, as a sealant for their canoes, as well as for war
paints and medicines. And archaeologists believe the ancient Egyptians
used the same substance as a lubricant on chariot wheels. The
Greeks are said to have used petroleum to set the sea on fire to
destroy a fleet of ships belonging to an enemy that was threatening
invasion.
It is thought that by the Middle Ages, Sicilians were gathering
oil off their coast to use as fuel for lamps. Europeans, in the meantime,
skimmed the natural springs for oil that they used for medicinal
purposes, as well as for fuel.
It was the Chinese, however, who first drilled for petroleum.
Using primitive drilling tools, they bored eight hundred feet into
the earth in 347 A.D.—fifteen centuries before the birth of the
modern-day petroleum industry!