Download Drilling and Completion: Offshore PTRT 1301

Chapter 8
This chapter focuses on the movement of crude by pipeline, although attention is also given to other transport modes,
including tanker vessels, railcars, and tank trucks.
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A network of gathering lines carries this oil from
the wells to a location in or near the oil field for
preliminary processing.

A separator at a well site is used to remove both
the natural gas and the water-usually contained
in any reservoir. Any solid materials (e.g., sand),
as well as some dissolved salts, are removed
from the raw crude.

Condensate is light hydrocarbon liquids
extracted during onsite natural gas separation.
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When the stored oil is ready for transportation, a technician usually
convert measured oil depth to oil volume.
 Measures the temperature of the oil
 Lowers a gauge tape into the tank to measure oil depth— similar to using a
dipstick to check a car engine’s oil level
 Takes a sample of the stored oil by dipping a small bottle into the tank or by
opening a small valve on the tank’s side
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Then, by calculation and analysis, the technician will:
 Convert the measured oil depth to oil volume, using a gauge table or
computer algorithm
 Separate basic sediment and water (BS&W) from the oil sample, using a
centrifuge
 Determine how much BS&W is contained in the measured oil volume.

Because volume of oil changes with temperature, industry
standards call for correcting the volume for a temperature of 60°F.

A given batch of oil moves at 3-4 miles per hour through a
mainline, propelled by centrifugal pumps sited every 20-100
miles (depending on terrain).

Points at which pipelines come together are called hubs (or
marine terminals if near a port). Significant storage volume is
generally available at such facilities. Short-haul lines are also
called spur, stub, or delivery lines.

A major hub for U.S. crude oil pipelines is in Cushing, Oklahoma
approximately 500 miles north of the Gulf of Mexico.

Other primary U.S. hubs and marine terminals for crude oil are at
New York Harbor; the Gulf Coast (Texas-Louisiana coast); Tulsa,
Oklahoma; Chicago; and Los Angeles.

Sumed (Suez-Mediterranean) Pipeline moves 2.5 million b/d Saudi
and other Mideast oil to Europe across Egypt.

Most sections of an oil
pipeline operate at relatively
low pressure (up to about 150
psi). Pipe in these sections is
made from various types of
plastic, fiberglass, or steel.

Most pipelines are buried
three to six feet below the
ground.

On January 18, 2012,
President Barack Obama
denied a construction permit
for the Keystone XL pipeline.

Steel pipe is fabricated with various
wall thicknesses and OD ranging
from 4.5 to 48 inches.

The pipe is also coated/ wrapped to
protect it from rust, chemical attack,
and electrical current flow using
materials ranging from fusion-bond
epoxy, coal tar, plastics, and tapes to
shrink sleeves and even concrete.

SCADA systems are used to control
a wide range of large-scale industrial
and utility systems, including oil and
gas pipelines.
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Valves (and their actuators) control or cut off oil flow in
response to operational changes, maintenance needs, or
emergencies
Pumps maintain pressure levels to keep the oil flowing
(analogous to a compressor in a natural gas pipeline)
Electric motors, engines, and turbines (running on
liquid fuels or natural gas) that provide the power needed
to run pumps
Meters that accurately measure the amount of oil being
moved or delivered
Other instruments, sensors, and computer-linked
components that provide real-time information about
the condition of all sections of a pipeline

Pipeline and Hazardous Materials Safety Administration
[PHMSA]), the Association of Oil Pipe Lines, the American
Society of Mechanical Engineers, API, and the Interstate
Natural Gas Association of America governmental and
industry organizations track and report releases from U.S.
pipelines.
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Third-party damage to pipelines and equipment
Corrosion (internal and external) and stress corrosion cracking
Mechanical failures, including manufacturing and construction flaws
Natural hazards (ground motion, weather, erosion due to water
flow)
To assess condition of pipelines sophisticated internal line
inspection (ILI) device, called smart pig, that travel through a
pipeline looking for metal loss, wall deformation, and cracks.

SCADA systems are used to control a wide range
of large-scale industrial and utility systems,
including oil and gas pipelines.

In electrical current/voltage survey technicians
measure the difference in voltage between the
pipe and the adjacent soil or the magnitude of
current flow between two points on the pipeline.

Direct Assessment uses statistical analysis to
identify the most likely problem locations along a
pipeline.

Shell’s Perdido platform began
producing oil and gas in March
2010 from a network of 35 wells
at a water depth of about 8,000
feet.

Offshore pipes and equipment
must be strong enough to
handle both the crushing
pressure encountered at the
seafloor—about 2,700 psi at a
depth of 6,000 feet—as well as
the internal pressure needed to
lift oil to sea level.

A jumper steel or flexible
composite pipe typically 6–12
inches in diameter—carries
hydrocarbons to a manifold if
the distance is about 100 feet or
less. For longer distances (up to
tens of miles), the connecting
pipe is called a flowline.

Lines and manifolds on or close
to the seafloor are typically
insulated to counteract the
effects of water temperatures
as low as 30°F.

Hydrate is a crystalline
material, similar in appearance
to a snowball, in which
methane molecules are trapped
in a lattice of water molecules.

The production riser pipe carries collected
hydrocarbons upward to the production
platform, sometimes aided by pumps on the
seafloor.

Flexible pipes for off-shore are fabricated by
wrapping an inner steel carcass core with
alternating layers of steel wires and
thermoplastics.

After crude oil undergoes
initial cleanup aboard the
production platform, it is
either off-loaded to a
shuttle tanker for the trip to
shore or pumped down
through another riser
(called an export riser) to
enter a subsea pipeline.

One common method in
pipeline assembly is to
weld together and coat
pipe sections—typically 40–
240 feet long and 16–42
inches in diameter, with
walls at least 1 inch thick—
at a shore-based facility.

In j-shape pipeline assembly,
operators weld and coat the pipe
sections aboard specially designed
pipe-laying vessels that can be as
long as a football field. The
connected sections are then
gradually eased into the water from
the stern of the slow-moving vessel
as it follows the installation route.

In reel pipeline laying, suitable only
for laying pipe 6–18 inches in
diameter, operators weld together
and coat the pipe sections on land
and then wind the finished product
onto very large reels. (More than
30,000 feet of 6-inch pipe can fit on
one such reel).
The Cameron Highway Oil Pipeline System is
a 380-mile, 24- and 30-inch oil pipeline that
extends along the Outer Continental Shelf of
the Gulf of Mexico. It has the capacity to
deliver more than 600,000 b/d of oil from
several major deep-water fields to the Texas
coast, connecting directly with three refineries
and four terminals.

Crude oil is transported
around the world on
seagoing tanker ships -a
mode of delivery that is
second only to a pipeline in
cost-effectiveness.

Crude oil tankers are typically
classified by deadweight
metric tonnage (DWT)—the
displacement of a fully
loaded vessel minus its
weight when completely
empty (with no cargo, fuel,
ballast, crew, passengers,
water, or provisions).

A vessel’s cargocarrying capacity is
about 95% of its
deadweight metric
tonnage (DWT).
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Since 2010, no singlehull tanker vessel of
5,000 DWT or larger has
been allowed to operate
in U.S. waters unless it
has a double bottom or
double sides, under the
terms of the federal Oil
Pollution Act of 1990.
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The term supertanker is used for
very large crude carriers (VLCCs)
and ultra-large crude carriers
(ULCCs), which can carry a cargo
of more than 2 million barrels.
One DWT of capacity is
equivalent to about 7.5 barrels of
oil (though different grades of
crude have different densities).
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Barges are also used to move oil
between onshore storage
terminals. In 2010, some 92
million barrels of crude were
transported by barge in the
United States, according to EIA.

EIA reported that crude shipments from
domestic producers to U.S. refineries by
tanker truck totaled approximately 145
million barrels in 2010.

For railcars, the corresponding figure was
roughly 9 million barrels.

A facility with several storage tanks is
called a tank farm.

Salt caverns are also
used to store crude oil
(as well as natural gas
and propane). The
caverns are created
within underground salt
domes or beds by
pumping water into the
formation to dissolve the
salt. The brine is then
pumped out to leave a
hollow cavern.
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U.S. Strategic Petroleum Reserve (SPR)
consists of 4 sites, on the Gulf Coast, whose
exact locations are not disclosed for security
reasons.

According to EIA, approximately 4.1 billion
barrels of oil are held in strategic reserves
around the world (including in the United
States).