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The Chemistry and Technology of Petroleum
also be stored in such geological features as salt domes. The domes have been previously leached
or hollowed out into huge underground caves, such as those used by the US Strategic Petroleum
Reserve in Louisiana and Texas. Other underground storage facilities include disused coal mines
and artificial caverns. Natural gas is, on occasion, stored in old reservoirs from which the gas has
been recovered. The gas is pumped under pressure into the reservoir at times of low gas demand so
that it can be retrieved later to meet peak demand.
Large-scale transportation of crude oil, refined petroleum products, and natural gas is usually
accomplished by pipelines and tankers, while smaller-scale distribution, especially of petroleum
products, is carried out by barges, trucks, and rail tank cars. In fact, the transportation from the
source of the crude oil to the market is as old as the industry itself. Even the bitumen used in
Babylon and other cities of the Fertile Crescent had to be transported from the seepage at Hit to the
place where it would be used.
In more modern times, the transportation of crude oil from fields to refineries and of products to
market centers was at one time essentially dependent upon rail transportation. By the early 1970s,
the use of railroad tank cars had diminished to the point at which only a little over 1% of the total
petroleum tonnage was hauled by the railroads. Pipeline mileage increased to become the major
means of transportation.
There were two principal technological trends during that period that increased pipeline use:
(1) more widespread use was made of large diameter pipe; and (2) more efficient diesel pumps
became available for installation at stations along the line, replacing steam-driven models. In addition there were other developments such as (1) the introduction of welded rather than screwed-in
couplings; (2) the use of high carbon steel to replace lap-welded pipe; and (3) the replacement of diesel equipment by electrically powered pumps. At the present time, the pipeline used for petroleum
transportation may be up to 48 in. in diameter and may cover many thousands of miles.
Pipelines may be used to transport different types of crude oil (batch transportation). When the
different batches must be kept separated to prevent mixing, slugs of kerosene, water, or occasionally
inflatable rubber balls are used to separate the batches. However, there is also the possibility that
the batches can be transported through the pipelines without such separators. The properties of each
batch may be such that mixing, other than to form a narrow interface, is prevented. It is frequently
necessary to pass cylindrical steel cleaners (pigs) through the pipelines, between pumping stations,
to maintain the pipeline clear of deposits.
Tank trucks are used for both lock and intermediate hauling from manufacturing and distance
hauling from manufacturing and terminal points to individual domestic, commercial, and industrial
consumers that maintain storage tanks on their premises. Because of costs, most bulk deliveries by
truck fall within a radius of 300 miles.
Seagoing tankers (Table 6.4), on the other hand, can be sent to any destination where a port can
accommodate them and can be shifted to different routes according to need.
The seagoing tanker fleets that are owned, or used, by the world’s oil companies are also responsible for the movement of a considerable portion of the world’s crude oil. In fact, seagoing tankers
form one of the most characteristic features associated with the transportation of petroleum. Many
of these ships are of such a size that there are few ports that can handle them. Instead these large
ships (VLCCs, very large crude carriers, and ULCCs, ultra large crude carriers) spend their time
sailing the seas between different points, filling up and off-loading without ever entering port.
Special loading jetties, artificial islands, or large buoys moored far offshore have been developed to
load or off-load these tankers.
In general, the larger the tanker the lower its unit cost of transportation. As a result, the size of
tankers during the 1960s and 1970s grew steadily. During the 1930s and 1940s, the average size
of tankers was about 12,000 deadweight ton (dwt = the number of tons of cargo, stores, and fuel that
a ship can usually carry). By the 1950s, a 33,000 dwt tanker was considered standard size. At present, the VLCC and ULCC classes involve tankers of over 200,000 and 300,000 dwt. A few tankers
in the 500,000 dwt range also exist, and some have even exceeded this size.
The Chemistry and Technology of Petroleum
also be stored in such geological features as salt domes. The domes have been previously leached
or hollowed out into huge underground caves, such as those used by the US Strategic Petroleum
Reserve in Louisiana and Texas. Other underground storage facilities include disused coal mines
and artificial caverns. Natural gas is, on occasion, stored in old reservoirs from which the gas has
been recovered. The gas is pumped under pressure into the reservoir at times of low gas demand so
that it can be retrieved later to meet peak demand.
Large-scale transportation of crude oil, refined petroleum products, and natural gas is usually
accomplished by pipelines and tankers, while smaller-scale distribution, especially of petroleum
products, is carried out by barges, trucks, and rail tank cars. In fact, the transportation from the
source of the crude oil to the market is as old as the industry itself. Even the bitumen used in
Babylon and other cities of the Fertile Crescent had to be transported from the seepage at Hit to the
place where it would be used.
In more modern times, the transportation of crude oil from fields to refineries and of products to
market centers was at one time essentially dependent upon rail transportation. By the early 1970s,
the use of railroad tank cars had diminished to the point at which only a little over 1% of the total
petroleum tonnage was hauled by the railroads. Pipeline mileage increased to become the major
means of transportation.
There were two principal technological trends during that period that increased pipeline use:
(1) more widespread use was made of large diameter pipe; and (2) more efficient diesel pumps
became available for installation at stations along the line, replacing steam-driven models. In addition there were other developments such as (1) the introduction of welded rather than screwed-in
couplings; (2) the use of high carbon steel to replace lap-welded pipe; and (3) the replacement of diesel equipment by electrically powered pumps. At the present time, the pipeline used for petroleum
transportation may be up to 48 in. in diameter and may cover many thousands of miles.
Pipelines may be used to transport different types of crude oil (batch transportation). When the
different batches must be kept separated to prevent mixing, slugs of kerosene, water, or occasionally
inflatable rubber balls are used to separate the batches. However, there is also the possibility that
the batches can be transported through the pipelines without such separators. The properties of each
batch may be such that mixing, other than to form a narrow interface, is prevented. It is frequently
necessary to pass cylindrical steel cleaners (pigs) through the pipelines, between pumping stations,
to maintain the pipeline clear of deposits.
Tank trucks are used for both lock and intermediate hauling from manufacturing and distance
hauling from manufacturing and terminal points to individual domestic, commercial, and industrial
consumers that maintain storage tanks on their premises. Because of costs, most bulk deliveries by
truck fall within a radius of 300 miles.
Seagoing tankers (Table 6.4), on the other hand, can be sent to any destination where a port can
accommodate them and can be shifted to different routes according to need.
The seagoing tanker fleets that are owned, or used, by the world’s oil companies are also responsible for the movement of a considerable portion of the world’s crude oil. In fact, seagoing tankers
form one of the most characteristic features associated with the transportation of petroleum. Many
of these ships are of such a size that there are few ports that can handle them. Instead these large
ships (VLCCs, very large crude carriers, and ULCCs, ultra large crude carriers) spend their time
sailing the seas between different points, filling up and off-loading without ever entering port.
Special loading jetties, artificial islands, or large buoys moored far offshore have been developed to
load or off-load these tankers.
In general, the larger the tanker the lower its unit cost of transportation. As a result, the size of
tankers during the 1960s and 1970s grew steadily. During the 1930s and 1940s, the average size
of tankers was about 12,000 deadweight ton (dwt = the number of tons of cargo, stores, and fuel that
a ship can usually carry). By the 1950s, a 33,000 dwt tanker was considered standard size. At present, the VLCC and ULCC classes involve tankers of over 200,000 and 300,000 dwt. A few tankers
in the 500,000 dwt range also exist, and some have even exceeded this size.