Heavy crude oil is dense and viscous oil that does not flow easily. It has a higher density and lower API gravity than light crude oil. The largest reserves are in Venezuela. Production and refining of heavy crude presents challenges due to its properties. While resources are large, recovery rates are limited, though technology has increased rates. Heavy crude also has a greater environmental impact than light crude due to the energy needed for its extraction and processing. The document provides details on the geological origins, chemical properties, production methods, economics and environmental impacts of heavy crude oil.

1. HEAVY CRUDE OIL
By:
Muneer Basha
Introduction:
Heavy crude oil or extra heavy crude oil is any type of crude oil which does not flow easily. It
is referred to as "heavy" because its density or specific gravity is higher than that of light
crude oil. Heavy crude oil has been defined as any liquid petroleum with an API gravity less
than 20°. Physical properties that differ between heavy crudes lighter grades include higher
viscosity and specific gravity, as well as heavier molecular composition. Extra heavy oil is
defined with a gravity of less than 10° API (i.e. with density greater than 1000 kg/m3 or,
equivalently, a specific gravity greater than 1) and a reservoir viscosity of no more than
10,000 centipoises. With a specific gravity of greater than 1, extra heavy crude is present as a
dense non-aqueous phase liquid in ambient conditions.
Heavy crude oil is closely related to natural bitumen from oil sands. Some petroleum
geologists categorize bitumen from oil sands as extra heavy crude oil due to the density of
less than 10 °API. Other classifications label this as bitumen differing it from extra-heavy oil.
They differ in the degree by which they have been degraded from the original crude oil by
bacteria and erosion. Often, bitumen is present as a solid and does not flow at ambient
conditions.
The largest reserves of heavy crude oil in the world are located north of the Orinoco river in
Venezuela, the same amount as the conventional oil reserves of Saudi Arabia, but 30 or more
countries are known to have reserves.
Production, transportation, and refining of heavy crude oil present special challenges
compared to light crude oil. Generally, a diluent is added at regular distances in a pipeline
carrying heavy crude to facilitate its flow.
Economics:
Heavy crude oils provide an interesting situation for the economics of petroleum
development. The resources of heavy oil in the world are more than twice those of
conventional light crude oil. In October 2009, the USGS updated the Orinoco deposits
(Venezuela) recoverable value to 513 billion barrels (8.16×1010 m3), making this area the one
of the world's largest recoverable oil deposit. However, recovery rates for heavy oil are often
limited from 5-30% of oil in place. The chemical makeup is often the defining variable in
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2. recovery rates. Technology utilized for the recovery of heavy oil has steadily increased
recovery rates.
On one hand, due to increased refining costs and high sulfur content for some sources, heavy
crudes are often priced at a discount to lighter ones. The increased viscosity and density also
makes production more difficult (see reservoir engineering). On the other hand, large
quantities of heavy crudes have been discovered in the Americas including Canada,
Venezuela and California. The relatively shallow depth of heavy oil fields (often less than
3000 feet) can contribute to lower production costs; however, these are offset by the
difficulties of production and transport that render conventional production methods
ineffective. Specialized techniques are being developed for exploration and production of
heavy oil.
Extraction:
Production of heavy oil is becoming more common in many countries, with 2008
production led by Canada and Venezuela. Methods for extraction include Cold heavy oil
production with sand, steam assisted gravity drainage, cyclic steam stimulation, vapor
extraction, Toe-to-Heel Air Injection (THAI), and open-pit mining for extremely sandy and oil-
rich deposits.
Environmental Impact:
With current production and transportation methods, heavy crudes have a more
severe environmental impact than light ones. With more difficult production comes the
employment of a variety of enhanced oil recovery techniques, including steam flooding and
tighter well spacing, often as close as one well per acre. Heavy crudes also carry
contaminants. For example, Orinoco extra heavy oil contains 4.5% sulfur as well as vanadium
and nickel. However, because crude oil is refined before use, generating specific alkanes via
cracking and fractional distillation, this comparison is not valid in a practical sense. Heavy
crude refining techniques may require more energy input[citation needed] though, so its
environmental impact is presently much more significant than that of lighter crude.[citation
needed]
With present technology, the extraction and refining of heavy oils and oil sands generates as
much as three times the total CO2 emissions compared to conventional oil, primarily driven
by the extra energy consumption of the extraction process (which may include burning
natural gas to heat and pressurize the reservoir to stimulate flow). Current research in to
better production methods seek to reduce this environmental impact.
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3. In a 2009 report, the National Toxics Network, citing data provided by the Carbon Dioxide
Information Analysis Center of the government of the United States and the Canadian
Association of Petroleum Producers (CAPP), found that heavy oils can have higher CO2
emissions per ton than coal. Emissions were lower than coal on a "per unit of energy
produced" basis, at about 84% of those for coal (0.078/0.093) and thus higher on this basis of
CO2 emissions, than conventional oil.
Environmental Research Web has reported that "because of the energy needed for extraction
and processing, petroleum from Canadian oil tar sands has higher life cycle emission" versus
conventional fossil fuels; "up to 25% more."
Geological Origin:
Most geologists agree that crude becomes "heavy" as a result of biodegradation, in
which lighter ends are preferentially consumed by bacterial activity in the reservoir, leaving
heavier hydrocarbons behind. This hypothesis leans heavily on the techniques of petroleum
geochemistry. Poor geologic reservoir sealing exposes the hydrocarbon to surface
contaminants, including organic life (such as bacteria) and contributes to this process.
Heavy oils can be found in shallow, young reservoirs, with rocks from the Pleistocene,
Pliocene, and Miocene (younger than 25 million years). In some cases, it can also be found in
older Cretaceous, Mississippian, and Devonian reservoirs. These reservoirs tend to be poorly
sealed, resulting in heavy oil and oil-sands.
Chemical Properties:
Heavy oil is asphaltic and contains asphaltenes and resins. It is "heavy" (dense and
viscous) due to the high ratio of aromatics and naphthenes to paraffins (linear alkanes) and
high amounts of NSO's (nitrogen, sulfur, oxygen and heavy metals). Heavy oil has a higher
percentage of compounds with over 60 carbon atoms and hence a high boiling point and
molecular weight. For example, the viscosity of Venezuela's Orinoco extra-heavy crude oil lies
in the range 1000–5000 cP (1–5 Pa·s), while Canadian extra-heavy crude has a viscosity in the
range 5000–10,000 cP (5–10 Pa·s), about the same as molasses, and higher (up to 100,000 cP
or 100 Pa·s for the most viscous commercially exploitable deposits).A definition from the
Chevron Phillips Chemical company is as follows:
The "heaviness" of heavy oil is primarily the result of a relatively high proportion of a mixed
bag of complex, high molecular weight, non-paraffinic compounds and a low proportion of
volatile, low molecular weight compounds. Heavy oils typically contain very little paraffin and
may or may not contain high levels of asphaltenes.
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4. There are two main types of heavy crude oil:
Those that have over 1% sulfur (high sulfur crude oils), with aromatics and
asphaltenes, and these are mostly found in North America (Canada (Alberta, Saskatchewan),
United States (California), Mexico), South America (Venezuela, Colombia and Ecuador) and
the Middle East (Kuwait, Saudi Arabia).
Those that have less than 1% sulfur (low sulfur crude oils), with aromatics, naphthenes and
resins, and these are mostly found in Western Africa (Chad), Central Africa (Angola) and East
Africa (Madagascar).
Companies and organizations:
Major petroleumcompanies
Super majors
BP
Chevron
ConocoPhillips
ExxonMobil
Royal Dutch Shell
Total
National oilcompanies
ADNOC
CNOOC
CNPC
Iraq National Oil Company
Indian Oil Corporation
Kuwait Petroleum Corporation
Nigerian National Petroleum Corporation
NIOC
ONGC
Orlen
PDVSA
Pemex
Pertamina
Petrobras
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5. Petronas
Qatar Petroleum
Rosneft
Saudi Aramco
Sonangol
Sonatrach
Other:
Anadarko
Apache
BG Group
Cenovus Energy
Devon
Eni
GalpEnergia
Gazprom
Hess
Husky Energy
Imperial Oil
Lukoil
Marathon Oil
Nippon Oil
Occidental
OMV
PetroChina
Reliance Industries
Repsol YPF
Sinopec
Statoil
Suncor Energy
Surgutneftegas
TNK-BP
Major services companies:
AMEC
Baker Hughes
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6. CGGVeritas
CH2M HILL
China Oilfield Services
Enbridge
Ensco
GE Oil & Gas
Halliburton
NaftiranIntertrade
National Oilwell Varco
Petrofac
Saipem
Schlumberger
Snam
Technip
TransCanada
Transocean
Weatherford
Wood Group
Other:
International Association of Oil & Gas Producers
International Energy Agency
International Petroleum Exchange
OPEC
Society of Petroleum Engineers
World Petroleum Council
Data:
Natural gas
Consumption
Production
Reserves
Imports
Exports
Price
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7. Petroleum
Consumption
Production
Reserves
Imports
Exports
Price (Price of gasoline and diesel)
Exploration andproduction:
Exploration:
Core sampling
Geophysics
Integrated asset modelling
Petroleum engineering
Reservoir simulation
Seismic to simulation
Petroleum geology
Petrophysics
Reflection seismology (Seismic inversion)
Seismic source
Drilling:
Blowouts
Completion (Squeeze job)
Differential sticking
Directional drilling (Geosteering)
Drilling engineering
Drilling fluid
Drilling fluid invasion
Drill stem test
Lost circulation
Measurement
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8. Tracers
Underbalanced drilling
Well logging
Production:
Agreements
o Concessions
o Production sharing agreements
Artificial lift
o Pumpjack
o Submersible pump (ESP)
o Gas lift
Downstream
Enhanced oil recovery (EOR)
o Steam injection
o Gas reinjection
Midstream
Petroleum product
Pipeline transport
Refining
Upstream
Water injection
Well intervention
XT
History:
1967 Oil Embargo
1973 oil crisis
1979 energy crisis
1980s oil glut
2000s energy crisis
Founders
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9. History of petroleum
Nationalization
Seven Sisters
Standard Oil
Oil market timelines
Provinces and fields
List of natural gas fields
List of oil fields
East Texas
Gulf of Mexico
Niger Delta
North Sea
Persian Gulf
Prudhoe Bay Oil Field
Russia
Venezuela
Western Canadian Sedimentary Basin
Other
Acronymns
Peak oil
o Mitigation
o Timing
People
Petrocurrency
Petrodollar
Petroeuro
Shale gas
Swing producer
Unconventional oil
Heavy crude oil:
o Oil sands
o Oil shale
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10. What is Crude Oil?
Crude oil, commonly known as petroleum, is a liquid found within the Earth comprised of
hydrocarbons, organic compounds and small amounts of metal. While hydrocarbons are
usually the primary component of crude oil, their composition can vary from 50%-97%
depending on the type of crude oil and how it is extracted. Organic compounds like nitrogen,
oxygen, and sulfur typically make-up between 6%-10% of crude oil while metals such as
copper, nickel, vanadium and iron account for less than 1% of the total composition.
Crude Oil Formation:
Crude oil is created through the heating and compression of organic materials over
a long period of time. Most of the oil we extract today comes from the remains of prehistoric
algae and zooplankton whose remains settled on the bottom of an Ocean or Lake. Over time
this organic material combined with mud and was then heated to high temperatures from the
pressure created by heavy layers of sediment. This process, known as diagenesis, changes the
chemical composition first into a waxy compound called kerogen and then, with increased
heat, into a liquid through a process called catagenesis.
Crude Oil Extraction:
The most common method of crude oil extraction is drilling. Geologists will first
identify a section of land they believe has oil flowing beneath it. There are a number of ways
this can be accomplished, the most frequently used methods are satellite imagery, gravity
meters, and magnetometers. Once a steady stream of oil is found, underground the drilling
can begin.
Drilling is not an overly complicated process however a standard method has been developed
to provide maximum efficiency. The first step of the process involves drilling into the ground
in the exact location where the oil is located. Once a steady flow has been identified at a
particular depth beneath the ground a perforating gun is lowered into the well. A perforating
gun has explosive charges within it that allow for oil to flow through holes in the casing. Once
the casing is properly perforated a tube is run into the hole allowing the oil and gas to flow up
the well. To seal the tubing a device called a packer is run along the outside of the tube. The
last step involves the placement of a structure called a Christmas tree which allows oil
workers to control the flow of oil from the well.
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11. Oil Sands:
Oil can also be extracted from oil sands, often called tar sands. Oils sands are
typically sand or clay mixed with water and a very viscous form of crude oil known as
bitumen. The extraction process for oil sands is quite different from drilling due to the high
viscosity of this extra-heavy oil. Rather than using drills, crude oil is extracted from oil sands
through strip mining or a variety of other techniques used to reduce the viscosity of the oil.
This process can be far more expensive than traditional drilling and is found in high
abundance only in Canada and Venezuela. As oil demand continues to rise, and reserves
become depleted, oil sands could provide one of the last viable methods for extracting crude
oil from the Earth.
Worldwide Oil Production:
While just about every country in the world depends on oil, not all countries
produce it. The top five oil producing countries are: Saudi Arabia, Russia, United States, Iran,
and China. It is important to note that the term production here refers to crude oil extracted
from oil reserves. The top five oil consuming countries are: United States, China, Japan,
Russia, and Germany.
At the current rate of consumption it is estimated that worldwide reserves will become
extinguished by 2039. Scientists and engineers are working hard to find ways of more
efficiently extracting and processing crude oil to delay what could become a global energy
crisis.
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