National Academies Press: OpenBook
« Previous: 1 Introduction
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

2

Chemical and Physical
Properties of Crude Oils

INTRODUCTION

Crude oil derives, by way of geological processing, from organic material initially buried in sediments at the bottom of ancient lakes and oceans. Crude oil formed at depth in a sedimentary basin migrates upward because of lower density. Many such migrations end with the oil collecting beneath a layer of impermeable rock, also referred to as a “trap,” and forming a reservoir that can be tapped by drilling.

If the oil approaches the surface, it cools and comes in contact with groundwater. At the oil-water interface, anaerobic microorganisms degrade the oil in the absence of oxygen. The progressive loss of metabolizable molecules from the oil leads to an increase in viscosity and eventually results in a tarry residue that clogs the pores of the strata through which the oil had been migrating. Over a long duration and with adequate sources of oil from below, enormous deposits of biodegraded oil residue can accumulate. This sequence is how the Alberta oil sands21 and other oil-sand deposits were formed.

Bitumen is separated from the host rock or sand by heating, which reduces its viscosity so that it can flow to a collection point. Once collected, it is mixed with a diluent so that its viscosity is low enough to allow transport in a transmission pipeline. Such mixtures are called diluted bitumen.

Diluted bitumen are engineered to resemble other crude oils that are transported via pipeline and processed in the same refineries. The composition of diluted bitumen is dependent on several factors, particularly the

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

diluent or diluents chosen and the diluent-to-bitumen ratio. As a result, diluted bitumen has dimensions of variability significantly exceeding those of crude oil from a given source region.21

CHEMICAL COMPOSITION OF DILUTED BITUMEN

Diluted bitumen and other crude oils generally contain the same classes of compounds, but the relative abundances of those classes vary widely. Those variations are associated in turn with wide differences in physical and chemical properties. Industry-standard analyses group compounds into four main classes, namely saturated hydrocarbons, aromatic hydrocarbons, resins, and asphaltenes. Saturated hydrocarbons are most abundant in light crude oils, which are the least dense and least viscous. Denser and more viscous crude oils have greater concentrations of other components, including resins and asphaltenes, which contain more polar compounds, often including “heteroatoms” of nitrogen, sulfur, and oxygen as well as carbon and hydrogen.

Even among light or medium crude oils, the relative abundances of specific compounds can vary significantly. The relative abundances will depend on the precise composition of the organic material delivered to the source sediments, the rate and length of time over which the source rock was heated, which inorganic minerals—potential catalysts of specific chemical reactions—were present in the source rock, the distance and details of the migration pathway, and conditions in the reservoir. In Table 2-1 and Figure 2-1, North American crude oils of each type for which data are readily available are provided as representative examples.22

From light, to medium and heavy crudes, and on to diluted bitumen, the abundance of saturated hydrocarbons drops 4-fold and the combined abundances of resins and asphaltenes increase 50-fold. These differences

TABLE 2-1 Major Classes of Compounds in Crude Oils, Percentages by Weight

Type of Crude Oil Saturates Aromatics Resins Asphaltenes
Light Crudea 92 8 1 0
Medium Crudeb 78 15 6 1
Heavy Crudec 38 29 20 13
Diluted Bitumend 25 22 33 20

aScotia Light.
bWest Texas Intermediate.
cSockeye Sour.
dCold Lake Blend.
SOURCE: Hollebone22

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

images

FIGURE 2-1 Components of typical crude oils.

are attributable mainly to the great influence of biodegradation on the heavier crude oil and bitumen.

Saturated Hydrocarbons

Under the anaerobic conditions prevailing during formation of the oil sands, the saturated hydrocarbons are mostly biodegradable, the aromatic hydrocarbons much less so, and the resins and asphaltenes not at all. A heavy crude, or the bitumen from an oil sand, is composed of the residue from a very protracted process whereby microbial action consumes most of the metabolizable saturates.

The saturated hydrocarbon fraction in diluted bitumen thus differs from that in other crude oils because the readily metabolizable molecules are missing. This is seen most dramatically in chemical analyses that reveal the distribution of individual compounds in the crude oil. For example, the graphs in Figure 2-2 show results of parallel analyses of samples of Cold Lake Blend diluted bitumen and Bakken crude oil.23 The latter is dominated by a strong series of peaks representing its abundant, straight-chain, saturated hydrocarbons. The diluted bitumen, in contrast, is dominated by a hump representing the profusion of branched and cyclic hydrocarbons that are more resistant to biodegradation. These are so numerous and varied that their peaks overlap and they cannot be resolved by this gas chromatographic analysis. The diluted bitumen has a small series of peaks indicating the presence of some straight-chain hydrocarbons that derive from the diluent.

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

images

FIGURE 2-2 Gas chromatography (GC) comparison of Cold Lake Blend diluted bitumen and Bakken crude oil, a light crude, from North Dakota (FID, flame ionization detector).
SOURCE: Swarthout, et al.23

Aromatic Hydrocarbons

Crude oils contain aromatic hydrocarbons possessing one or more aromatic rings. Those with more than one ring are commonly referred to as polycyclic aromatic hydrocarbons (PAHs). The one-ring compounds are most abundant and are referred to collectively as BTEX, an acronym based on the chemical names of benzene, toluene, ethyl benzene, and xylenes. The most common aromatic hydrocarbons with two rings are naphthalenes. Other commonly measured groups include the three-ring phenanthrenes, dibenzothiophenes, and fluorenes and also the four-ring chrysenes.

The napthalenes and the even larger phenanthrenes are progressively less volatile and soluble compared to BTEX. PAHs are present as unsubstituted or parent forms but the vast majority are alkyl substituted PAHs.

The aromatic hydrocarbons are of interest because of their toxicity. Specific properties and risks are discussed in Chapter 3. In Table 2-2, abundances of commonly measured PAHs in crude oils and in diluted

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

bitumen are listed. Values listed in red mark cases in which the concentration in diluted bitumen exceeds that in the other crude oils indicated.

Resins and Asphaltenes

The resins and asphaltenes characteristic of heavy crudes and diluted bitumen can precipitate from the oil as black sludge and cause numerous problems: clogging well bores, pipelines, and apparatus.24 Moreover, refining costs increase with the abundances of resins and asphaltenes.24 For all of those reasons, light and medium crudes have been favored. With increasing pressure on supplies, and with continued improvements in refining processes, heavy crude oils have come into broader use. As shown by Table 2-1, the content of resins and asphaltenes in light and medium crude oils is very much lower than that in heavy crude oils, and lower still than that in diluted bitumen.

The resins and asphaltenes have presented major challenges to chemical analysts.24 The range of structures and the tendency of the molecules to cluster in larger, multimolecular aggregates make it difficult to determine even rudimentary properties like molecular weight. It has been shown only recently25 that most individual molecules in the heavy residues have from 30 to 70 carbon atoms. They comprise a complex mixture of polycyclic molecular structures in that range. These molecules tend to stick together, not only in bulk (the property that makes asphalt an attractive paving material) but even at the low concentrations prevailing when samples are injected into analytical instruments. The resulting “nanoaggregates” have masses two to five times higher than those of the molecules of which they are composed. The apparent molecular weights are accordingly higher than the true molecular weights. Heteroatoms (mainly nitrogen, sulfur, and oxygen) and metals (mainly nickel, vanadium, and iron) are also present in higher relative abundances in the resin and asphaltene fractions than in the saturate fraction. As a result, the heteroatom content of bitumen is higher than that of other crude oils.

Chemical Composition of Diluents

The density and viscosity of raw bitumen are too great to allow transportation by transmission oil pipeline without heating or alteration of the material. To reduce the viscosity and density, a diluent must be added to bitumen to produce an engineered mixture with a density of less than 0.94 g/cm3 and a viscosity of less than 350 cSt. Additional industry-standard specifications that are largely a function of the operating temperature of the pipeline vary seasonally. Diluents alone do not confer unique chemical or toxicological properties to diluted bitumen;

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

TABLE 2-2 Concentrations of Parent and Alkylated PAHs, EPA Priority PAHs, and Total Aromatic Compounds in Various Crude Oils

Oil Type Light Medium Heavy Diluted Bitumen
Oil Sample Scotia Light oil26 West Texas oil27 Sockeye27 Cold Lake Blend28
Specific Compounds Conc. (µg/g) Conc. (µg/g) Conc. (µg/g) Conc. (µg/g)
Total EPA 16 Priority PAHs* (µg/g) 139 514 218 176
Total Aromatic Compounds (µg/g) 3,504 7947 5,231 5,384
Parent and Alkylated PAHs        
Sum Naphthalene* C0-41 2692 5172 3422 2099
Sum Phenanthrene* C0-4 351 1295 1078 1242
Sum Dibenzothiophene C0-3 16.3 816 403 1250
Sum Fluorene* C0-3 358 458 184 535
Sum Chrysene* C0-3 17.9 100 60 200
Total parent and alkylated PAHs 3,434 7841 5,147 5,326
Biphenyl 25.9 68.5 34.23 6.58
Acenaphthylene* 3.91 11.08 6.72 2.16
Acenaphthene* 24.2 8.84 7.7 6.93
Anthracene* 1.57 1.00 2.2 N.D.
Fluoranthene* 2.93 2.12 1.22 4.31
Pyrene* 2.55 6.72 5.01 11.3
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Oil Type Light Medium Heavy Diluted Bitumen
Oil Type Light Medium Heavy Diluted Bitumen
Benz[a] anthracene* 1.41 1.24 3.18 2.52
Benzo[b] fluoranthene* 1.29 1.37 0.98 4.06
Benzo[k] fluoranthene* 0.30 0.37 0.40 0.81
Benzo[e]pyrene 1.33 3.48 1.59 4.10
Benzo[a]pyrene* 0.74 0.25 0.49 3.01
Perylene 1.10 0.12 19.32 7.16
Indeno[1,2,3-cd] pyrene* 0.38 0.18 N.D. 1.89
Dibenzo[ah] anthracene* 0.32 0.18 0.12 0.73
Benzo[ghi] perylene* 1.29 0.50 0.86 2.24

1N.D. = not detected. Red values indicate levels in Cold Lake Bitumen that are higher in comparison to Scotia Light and West Texas crude oils. C0 are parent unsubstituted PAHs and C1-C4 are the alkyl PAHs. *Denotes the 16 EPA priority PAHs (naphthalene, phenanthrene, fluorene, and chrysene use the C0 parent levels only).

all crude oils contain similar, light end components. The compositions of diluents, however, can strongly affect the weathering behavior of diluted bitumen, chiefly because the evaporation of a highly volatile diluent will more readily produce a heavy residue.

The individual selection of diluents varies depending on the desired outcome, the current cost of acquiring and transporting the diluent to the bitumen source, and other internal considerations of pipeline operators. Specific information about the diluents used is typically not publicly available. In general, diluents used fall into two broad categories: naturally occurring mixtures of light hydrocarbons, synthetic crude oil, or both.

Synthetic crude oil is produced by upgrading bitumen to reduce its density and viscosity for transport by pipeline. When mixed with bitumen to obtain the required viscosity and density, synthetic crude oils yield a product that can be handled efficiently and economically by conventional heavy oil refineries. A drawback is that supplies of synthetic crudes are limited by the availability of upgraders at the source of extraction and that roughly a 50:50 mixture of bitumen with synthetic crude oil is required to obtain the desired density and viscosity.

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

The alternative, and more commonly used, diluents are naturally occurring mixtures of light hydrocarbons. These light hydrocarbons are acquired from two sources: ultralight crude oils and gas condensates. Gas condensates are produced by separating most of the C3 and all of the C4 and higher hydrocarbons from natural gas. Because the ultralight crudes and gas condensates are less dense and less viscous than synthetic crude oil, diluent-to-bitumen ratios are roughly 30:70. The particular mixture of light hydrocarbons in the diluent can be important in spill response. If the diluent is dominated by lighter compounds (C4-C8), it can evaporate more readily in the event of a spill, yielding a dense and viscous residue that must be accounted for in response.

WEATHERING AND ITS EFFECTS ON PHYSICAL PROPERTIES

The behavior of a crude oil or diluted bitumen released into the environment is shaped not only by its chemical composition but also by its physical properties. Those of particular interest are density, viscosity, flash point, and adhesion. Oil spilled into the environment undergoes a series of physical and chemical changes that in combination are termed weathering. Weathering processes occur at different rates, but they begin as soon as oil is spilled and usually proceed most rapidly immediately after the spill. Most weathering processes are highly temperature dependent and will slow to insignificant rates as temperatures approach freezing.

The most important weathering process is evaporation,29 which accounts for the greatest losses of material. Over a period of several days, a light fuel such as gasoline evaporates completely at temperatures above freezing, whereas only a small percentage of bitumen evaporates. Importantly, properties of the residual oil change as the light components of the oil are removed.

Density

Given that the density of fresh water is 1.00 g/cm3 at environmental temperatures and the densities of crude oils commonly range from 0.7 to 0.99 g/cm3 (see Table 2-3), most oils will float on freshwater. Because the density of seawater is 1.03 g/cm3, even the heaviest oils will usually float on seawater. But evaporative losses of light components can lead to significant increases in density of the residual oil. The densities of some weathered, diluted bitumen and of undiluted bitumen can approach and possibly exceed that of freshwater. Accordingly, those materials can submerge and may sink to the bottom. In this respect, diluted bitumen differs not only from light and medium crude oils, but even from most conventional heavy crude oils. Details are shown in Table 2-3.

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

TABLE 2-3 Density Comparison of Typical Crude Oilsa

Type of Crude Oil Density Before Release Density After Initial Weathering (mass % loss in weathering) Density After Additional Weathering (mass % lost in weathering)
Light Crudeb 0.77 0.80 (25%) 0.84 (64%)
Medium Crudec 0.85 0.87 (10%) 0.90 (32%)
Heavy Cruded 0.94 0.97 (10%) 0.98 (19%)
Diluted Bitumene 0.92 0.98 (15%) 1.002 (30%)
Bitumen 0.998 1.002 (1%) 1.004 (2%)

aData in g/cm3 at 15°C; freshwater has a density of 1.00, seawater of 1.03.
bScotia Light.
cWest Texas Intermediate.
dSockeye Sour.
eCold Lake Blend.
SOURCE: Hollebone22

Importantly, as discussed in Chapter 3, as the density of a weathering oil approaches that of water, contact with even small amounts of sand, clay, or other suspended sediment can trigger submergence. For this reason, the density of the oil residue itself (i.e., not including any associated natural particulate matter) does not need to exceed that of water for the residue to sink from the surface.

Viscosity

Viscosity is defined as the resistance to flow of a liquid: the lower the viscosity, the more readily a liquid flows. For example, water has a low viscosity and flows readily, whereas honey, with a high viscosity, flows poorly. The viscosity of oil is largely determined by its content of large, polar molecules, namely resins and asphaltenes. The greater the percentage of light components such as saturates and the lower the amount of asphaltenes, the lower the viscosity. Temperature also affects viscosity, with a lower temperature resulting in a higher viscosity. The variations with temperature are commonly large. Oil that flows readily at 40ºC can become a slow-moving, viscous mass at 10ºC. Evaporative losses selectively remove lighter components and, consequently, increase the viscosity of the residual oil, as illustrated in Table 2-4.

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

TABLE 2-4 Viscosity Comparison of Typical Crude Oilsa

Type of Crude Oil Viscosity Before Release Viscosity After Initial Weathering (mass % loss in weathering) Viscosity After Additional Weathering (mass % lost in weathering)
Light Crudeb 1 2 (25%) 5 (64%)
Medium Crudec 9 16 (10%) 112 (32%)
Heavy Cruded 820 8,700 (10%) 475,000 (19%)
Diluted Bitumene 270 6,300 (15%) 50,000 (30%)
Bitumen 260,000 300,000 (1%) 400,000 (2%)

aData in mPa·s.
bScotia Light.
cWest Texas Intermediate.
dSockeye Sour.
eCold Lake Blend.
SOURCE: Hollebone22

Flash Point

The flash point of oil is the temperature at which the liquid produces vapors sufficient for ignition by an open flame. A liquid is considered to be flammable if its flash point is less than 60°C. There is a broad range of flash points for oils and petroleum products, many of which are considered flammable, especially when freshly spilled. Gasoline, which is flammable under all ambient conditions, poses a serious hazard when spilled. Many fresh crude oils and diluted bitumen have an abundance of volatile components and may be flammable for a day or longer after being spilled, depending on the rate at which highly volatile components are lost by evaporation. On the other hand, undiluted bitumen and heavy crude oils typically are not flammable. Table 2-5 provides a quantitative summary of these variations.

Adhesion

The adhesion or “stickiness” of some crude oils has been noted as a problem at several spills. The adhesion of a crude oil to the surfaces of rocks, built surfaces, and vegetation can greatly impede cleanup. Although important in the context of oil spill response, adhesion is a property that is not measured during industry-standard analyses of crude oils. However, a quantitative measure of adhesion has been developed30 and a comparison of some values appears in Table 2-6. The test measures the mass of oil, or of weathered oil, that will adhere to a steel needle that has been immersed in the sample for 30 min and then allowed to drain for

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

TABLE 2-5 Flash Point Comparison of Typical Crude Oilsa

Type of Crude Oil Flash Point Before Release Flash Point After Initial Weathering (mass % loss in weathering) Flash Point After Additional Weathering (mass % lost in weathering)
Light Crudeb <−30 23 (25%) 95 (64%)
Medium Crudec −10 33 (10%) >110 (32%)
Heavy Cruded −3 67 (10%) >95 (19%)
Diluted Bitumene <−35 >60 (15%) >70 (30%)
Bitumen >100 >100 (1%) >110 (2%)

aData in °C.
bScotia Light.
cWest Texas Intermediate.
dSockeye Sour.
eCold Lake Blend.
SOURCE: Hollebone22

30 min. As can be seen, diluted bitumen is much more strongly adhesive than light or medium crude oils, or their evaporated residues. The contrast is even greater than it may appear. Not only is the diluted bitumen residue more adhesive, there is much more of it relative to the discharge for a given spill, due to the greater abundances of resins and asphaltenes in diluted bitumen. A comparison of the adhesion for various crude oils is listed in Table 2-6.

TABLE 2-6 Adhesion Comparison of Typical Crude Oilsa

Type of Crude Oil Adhesion Before Release Adhesion After Initial Weathering (mass % loss in weathering) Adhesion After Additional Weathering (mass % lost in weathering)
Light Crudeb 0 2 (25%) 9 (64%)
Medium Crudec 12 17 (10%) 33 (32%)
Heavy Cruded 75 98 (10%) 605 (19%)
Diluted Bitumene 98 146 (6%) 1580 (20%)
Bitumen 575    

aData in g/m2.
bScotia Light.
cWest Texas Intermediate.
dSockeye Sour.
eCold Lake Blend.
SOURCE: Hollebone22

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

images

FIGURE 2-3 The relative proportions of light versus residual components in crude oils.
SOURCES: Hollebone22 and Environment Canada31

TABLE 2-7 Comparison of Important Crude Oil Properties

Type of Crude Oil Adhesion (g/m2) Density (g/cm3) Viscosity (mPa·s) Flash point (ºC)
Light Crudea 0 0.77 1 −30
Weatheredb Light Crude 9 0.84 5 95
Medium Crudec 12 0.85 8 −10
Weathered Medium Crude 33 0.90 112 >110
Heavy Cruded 75 0.94 820 −3
Weathered Heavy Crude 600 0.98 475,000 >95
Diluted Bitumene 98 0.92 270 −35
Weathered Diluted Bitumen 1,580 1.002 50,000 >70

aScotia Light.
bAfter additional weathering.
cWest Texas Intermediate.
dSockeye Sour.
eCold Lake Blend.
SOURCES: Hollebone22 and Environment Canada31

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

CONCLUSION

Crude oils are mixtures of hydrocarbon compounds ranging from smaller, volatile compounds to very large, nonvolatile compounds. The hydrocarbon structures found in oil include saturates, aromatics, and polar compounds that include resins and asphaltenes. The resins and asphaltenes are largely recalcitrant in the environment. They evaporate, dissolve, and degrade poorly and thus may accumulate as residues after a spill. The percentage of the saturates and aromatics—herein called the light components, in comparison to the heavy, residue-forming resins and asphaltenes—varies with oil type and is summarized in Figure 2-3.

The physical and chemical properties of diluted bitumen differ substantially from those of other crude oils, with key differences highlighted in Table 2-7. The distinct physical and chemical properties of diluted bitumen arise from two components: the bitumen provides the high-molecular-weight components that contribute most to density, viscosity, and adhesion; and the diluent contributes the low-molecular-weight compounds that confer volatility and flammability, and that determine the rate at which evaporation increases the density of the residual oil.

Because diluted bitumen has higher concentrations of resins and asphaltenes than most crude oils, spills of diluted bitumen products will produce relatively larger volumes of persistent residues. Such residues may be produced relatively rapidly when gas condensate has been used as the diluent, and these weathered residues display striking differences in behavior compared to other oils: exceptionally high levels of adhesion, density, and viscosity.22

Contrasts between diluted bitumen and other crude oils are strongly enhanced by weathering. Weathered heavy crude and especially weathered diluted bitumen are, for example, much more adhesive than the other oils. The densities of the oils also vary, with weathered heavy oils approaching the density of fresh water and weathered diluted bitumen possibly exceeding the density of fresh water.

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×

This page intentionally left blank.

Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 21
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 22
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 23
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 24
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 25
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 26
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 27
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 28
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 29
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 30
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 31
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 32
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 33
Suggested Citation:"2 Chemical and Physical Properties of Crude Oils." National Academies of Sciences, Engineering, and Medicine. 2016. Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. Washington, DC: The National Academies Press. doi: 10.17226/21834.
×
Page 34
Next: 3 Environmental Processes, Behavior, and Toxicity of Diluted Bitumen »
Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response Get This Book
×
Buy Paperback | $50.00 Buy Ebook | $39.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

Diluted bitumen has been transported by pipeline in the United States for more than 40 years, with the amount increasing recently as a result of improved extraction technologies and resulting increases in production and exportation of Canadian diluted bitumen. The increased importation of Canadian diluted bitumen to the United States has strained the existing pipeline capacity and contributed to the expansion of pipeline mileage over the past 5 years. Although rising North American crude oil production has resulted in greater transport of crude oil by rail or tanker, oil pipelines continue to deliver the vast majority of crude oil supplies to U.S. refineries.

Spills of Diluted Bitumen from Pipelines examines the current state of knowledge and identifies the relevant properties and characteristics of the transport, fate, and effects of diluted bitumen and commonly transported crude oils when spilled in the environment. This report assesses whether the differences between properties of diluted bitumen and those of other commonly transported crude oils warrant modifications to the regulations governing spill response plans and cleanup. Given the nature of pipeline operations, response planning, and the oil industry, the recommendations outlined in this study are broadly applicable to other modes of transportation as well.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!