6. Oil
A. Some oils, derivatives and relevant terms
Carbon content—The carbon content of petroleum, gasoline, kerosene, crude oil, and other liquid fuels is generally 84–88%.
Cracking—Using refinery techniques to break down long-chain oil molecules into specific useful carbon-based products of lower molecular weights.
Crude oil—“Raw petroleum as it comes from the earth . . . A bitumen of liquid consistency, comparatively volatile . . .” Crude petroleum has been classified as a “liquid mineral.” “The higher the crude, the higher the API gravity.”
API gravity = Degrees API = (141.5/specific gravity at 60° F) − 131.5. “The logic of this arcane formula has been lost in antiquity.” The API is the American Petroleum Institute. See also specific gravity, here.
The API of water = 10°. This corresponds to a density of 8.328 lbs/gal and a specific gravity of 1.00.
Heavy crude—“Defined here as oil of 20° gravity API or heavier.”
“Crude oil is largely made up of flammable hydrocarbons.”
Hydrocarbons—“Chemical mixtures of around 12 percent HYDROGEN (light gas vapor) and 82 percent CARBON (heavy black solid.) Hydrocarbons include thousands of different compounds.” My high school chemistry book made it even easier: “Chemicals composed of only the two elements—hydrogen and carbon—are called hydrocarbons.” When I was alive, hydrocarbons were frequently used to make herbicides and pesticides, as surfactants, protective coatings, synthetic fibers such as nylon, flavor enhancers, plastics and suchlike petrochemical conveniences.
“Hydrocarbons in gasoline have from 4 to 14 carbon atoms per molecule, and lubricating oils have up to 30 or more carbon atoms per molecule.”
See section 6C, beginning here, for mention of hydrocarbons as pollutants.
Okie gas—This ultralight oil condensate (API of 50°) had its fame in the 1930s. It could be burned in a car like gasoline.
Light crude—More than 30° API. Often colorless. “The light crudes tend to have more gasoline, naphtha and kerosene.” “Probably has few percent natural gas liquids.”
Medium crude—20 to 30° API. Color may vary between greenish-yellow to reddish.
Heavy crude—10 to 20° API. This grade is usually black. “The heavy crudes tend to have more gas oil and residue.” “Has little or no natural gas liquids and a high percentage of the heavy hydrocarbons.”
Sweet crudes contain less than 0.05% sulfur, while sour crudes have 1.5% or more. Sweet crudes smell like gas, sour crudes smell like rotten eggs and aromatic crudes “have a sickly fruity smell.” In 2014, the Bakken formation in North Dakota happened to be one strong producer of light sweet crude, while Venezuela was afflicted with “heavier crudes that fetch less than international benchmarks.”
Diesel fuel—“Varies greatly in its characteristics, ranging from light distillates which are practically heavy kerosenes, to . . . crude oils.” “Diesel fuel contains [12 percent] more heat energy per gallon than gasoline,” but only if measured per cubic foot. In the table of Calorific Efficiencies here, header 201–217, I measure per pound, to be consistent with coal measurements.
Diesel grade 1-D—For high-speed engines, wide speed variations and low fuel temperatures.
Grade 2-D—Less volatile and higher in “heat energy” per gallon than 1-D. Used for high loads and uniform speeds.
Grade 4-D—“More viscous distillates and blends of these distillates with residual fuel oil.” Used in low- and medium-speed engines; best for sustained loads at constant speeds.
Gasoline—“A complex mixture of hydrocarbons which distill within the range of 100 to 400 [degrees] F[ahrenheit].” A member of the pentane group, which are all liquids (“commonly called distillates”). “Mildly toxic by inhalation . . . Questionable carcinogen . . . Some addiction has been reported from inhalation of fumes. Even brief inhalation of high concentrations can cause a fatal pulmonary edema.” “The combustion of gasoline, pound for pound, produces more total energy than dynamite.” A significant source of climate change.
Kerosene—“Less volatile than gasoline . . . obtained by continuing the distillation of crude petroleum after gasoline has been removed.” “Except for severe arctic areas where Jet B fuel is used, essentially all civil aviation uses kerosene fuel.”
Naphtha—“Refers to the light end fractions distilled from crude petroleum . . . a complex mixture of hydrocarbons with an end boiling point of about 165° C . . .”
Nylon—The name of this famous polymer (invented in 1938) derives from “New York” and “London,” the homes of the two relevant laboratories. Derived from adipic acid [see here].
Octane rating [of gasoline]—“Indicates its ability to resist knocking or pinging.”
Oil—It comes, perhaps, from plankton in ancient inland seas. [But see Sam Hewes’s caveat on II:486.] Since the water was poorly oxygenated, the dead plankton could not decompose. The pressure of sediments accumulating over it then produced heat, “initiating chemical reactions that convert the dead organic matter into oil. Bacteria appear to play a much greater role . . . than was previously thought. The ideal temperatures . . . are between 50° and 180° C, which are usually found at depths of between 2 and 4 kilometres.” “Of the light oils the most important is known as petrol. It is not a definite chemical compound. It is a mixture of various hydrocarbons of the paraffin and olefine series, produced from the distillation of petroleum and paraffin oils.”
“About two to two-and-one-half barrels of oil can be produced from a [short] ton of coal.”
For other conversions from barrels to tons, see barrel in section 6E, here.
“Between four and five [metric] tons of tar sand must be processed to make one barrel of oil.”
Tar sands—“Also known as oil sands . . . A combination of clay, sand, water, and bitumen (a heavy viscous oil) that is either mined or recovered by injecting steam or another heat source underground.” “Heavy hydrocarbons mixed with sand and dirt . . . One [processing method] is to submerge the tar sand in hot water and steam. This forms a . . . slurry that melts and liquefies the tar,” which rises to the surface.
“In 2009, 16.9 billion barrels, or about 99% of Alberta’s total proven oil reserves, were attributed to the oil sands—around 13% of total global oil reserves . . . Alberta ranks second after Saudi Arabia in proven oil reserves . . .”—Canada Yearbook 2011.
“With today’s refining methods, almost 50 percent of each crude oil barrel can be made into automotive gasoline.”
A table (ca. 1987) of “average yield from a barrel of crude oil” shows 15.7% going into “other products and losses.”
Oil shale—“A convenient expression used to cover a range of materials containing organic matter which can be converted to crude shale oil and gas by heating.” Or, if you prefer, “a sedimentary mineral that contains kerogen, a mixture of complex, high molecular weight organic polymers.” Can yield various motor fuels and other crude oil derivatives.
Petroleum—“A thick flammable dark-yellow to brown or green-black liquid . . . Insol[uble] in water; sol[uble] in benzene, chloroform, ether . . . Questionable carcinogen with experimental carcinogenic, neoplastigenic, and tumorigenic data by skin contact.” Unquestionable global warming agent.
Petroleum distillate—“Mildly toxic by inhalation and ingestion.”
Petroleum spirits—“A poison by intravenous route. Mildly toxic by inhalation.”
Plastic—A category of artificial carbon-based polymer. “Often designed to mimic the properties of natural materials . . . Produced by the conversion of natural products or . . . synthesis from primary chemicals generally coming from oil, natural gas, or coal. Most plastics are based on the carbon atom. Silicones, which are based on the silicon atom, are an exception.” Plastics are one of the “big five” products that use the lion’s share of industrial energy [see below].
Polymer—A compound made up of large molecules which in turn are composed of numerous small molecules. Carbon is famous for its ability to polymerize. Natural carbon polymers include proteins.
The “big five”—Aluminum, steel, cement, paper and plastics (ca. 2010). see here.
Residual fuel oil—“The source fuel for combustion in electric generating plants. Residual oil is what remains after lighter hydrocarbons, such as gasoline, have been extracted from crude oil.”
Synthesis gas—“A mixture of carbon monoxide . . . and hydrogen . . . that is the beginning of a wide range of chemicals.” Often derived from oil.
Tar sands—See oil.
B. Oil extraction and refining terms
For definitions relevant to fracking (which can produce both oil and natural gas), see section 5B, here.
Alkylation—“Changes small hydrocarbon compounds into larger ones.” “Changes LIGHT GASES (bottled types) into gasoline.” “One of the few refining processes that can produce . . . high octane . . . gasoline in large quantities.”
Catalytic cracking—“Moderate heat” and a catalyst (“usually a special clay powder”) are employed to transform “heavy fractions of crude oil into lighter ones (gasoline).”
Condensate—“A vaporous mixture of gas and water that is far less toxic and less flammable [than natural gas].” “The liquid resulting when a hydrocarbon is subjected to cooling and/or pressure reduction. Also, liquid hydrocarbons condensed from gas and oil wells.”
Distillation—See fractionating. Distillation alone can turn 20% of a given quantity of oil into gasoline. “With today’s refining methods, almost 50 percent of each crude oil barrel can be made into automotive gasoline.” (Both of these are 1987 figures.) See alkylation, catalytic cracking, hydrocracking, polymerization.
Fractionating—The procedure of distilling crude oil into its derivatives by making use of the different boiling points of the latter. For example, propane boils at −44° F, while butane boils at +31° F. Butanes and lighter products are fractionated, off at under 90° F, gasoline at 90–220°, then naphtha, kerosene, gas oil at their own unique intermediate temperatures, and finally the residues at 800° and higher.
Hydrocracking—“Separation” of oil molecules “occurs in the presence of hydrogen gas and a catalyst.” This method is commonly employed to produce unleaded premium gasoline.
Polymerization—“Produces gasoline out of very light gases,” but the result is feeble in antiknock properties.
Roughneck—“A specific term for a job on the rig crew, one up from roustabout, but also a generic term used for anyone who survives the job and graduates . . .”
Thermal cracking—An outmoded process which “used extreme heat—above 100° F . . .—and extreme pressures of around 1000 psi . . . to break large hydrocarbon compounds into smaller gasoline type hydrocarbons.”
Wellhead—“A device that controls pressure in the well and flow of gas or oil from the well.”
C. Some common oil pollutants and oil diseases
Car-generated pollution—In 1972 “the main source of pollution” from cars was “from incomplete burning of the gasoline.” Until the 1970s the “three most dangerous pollutants” were given as hydrocarbons, carbon monoxides and nitrogen oxides. In “the early 70s” lead additives joined the list. Carbon dioxide passed unmentioned.
Hydrocarbons—[For more on hydrocarbons, see sec. 6A, here.] Hydrocarbons and nitrogen oxides (both of which occur in internal combustion vehicle exhaust) combine in the presence of the ultraviolet radiation we receive from the sun. One chemical product is ozone (which protects us from global warming and radiation when it is in the upper atmosphere); another is peroxyacetyl nitrate. These two substances harm mucous membranes such as lung tissue; they can also kill plants.
Lead—“Around a teaspoon of lead is added to a gallon of leaded gasoline. This can increase octane and antiknock value of fuel as much as 7 or 8 octane numbers.” Lead “slows down the burning time of the fuel and eliminates the destructive ‘knock.’” Furthermore, it “allows the use of more efficient fuels and so cut[s] the cost of operating the vehicle.” But it causes harm to brains and nervous systems, hence the widespread banning of this additive.
Volatile organic compounds [VOCs]—Various polluting gases given off from oil and gas wells; many are said to harm human health; they also play a role in global warming; section 12 (here) and II:352.
D. Oil companies, acronyms and localisms: Abu Dhabi Emirate
ADCO—Abu Dhabi Company for Onshore Petroleum Operations Ltd.
ADNOC—Abu Dhabi National Oil Company.
EAD—Environment Agency Abu Dhabi, whose air quality reports are referenced in the Emirati chapter (see II:540n).
Halliburton—Listed in Abu Dhabi yellow pages under “Oilfield Equipment Suppliers” and “Oilfield Contractors & Services.”
Takreer—“In U.A.E. that name is very biggest company,” said my interpreter Ravindra. The acronym meant “Abu Dhabi Oil Refinery Company.”
Taqa—Abu Dhabi National Energy Co. PJSC.
E. Units and conversions
Barrel—“Conversion factors vary depending on oil source.”
1 barrel of petroleum = 42 gallons = 159 liters
“To convert t/d to bbl/d, multiply by 7.”
Barrels per metric ton of refined product:
Asphalt: 6.06
Residual fuel oil: 6.77
Kerosene: 7.75
Jet fuel: 8.00
“Motor gasoline”: 8.50
“Natural gasoline”: 10.00
Specific gravity—For many technical computations, the weight of a given amount of the compound, divided by the weight of the same amount of water. For a gas, the specific gravity is usually a volumetric comparison with air.
The API gravity [see here] of an oil (expressed in degrees) = (141.5/specific gravity at 60°F) − 131.5.
Here are some APIs: of asphalt, 11; of heavy crude, 18; of light crude; 36; of gasoline, 60.
Ton of oil equivalent (toe)—“A tonne of oil equivalent is defined as 107 kcal (41.868 GJ), a convenient measure because it is approximately the net heat content of one ton of average crude oil. This unit is used by the IEA/OECD in its energy balances.” (Note that “tonne” = “metric ton”; see here.) For more discussion of this unit, see section 4E, here.
Since 1 kcal = 3.968 BTUs, 1 toe = 39,680,000 BTUs.
1 toe = 1.429 tce [ton of coal equivalent] = 10 tons TNT equivalent = 11.6 MWh [megawatt-hours], or about 40 million BTUs.
“One metric ton of crude oil varies from about 1.5 per cent to 8 per cent above the value of 107 kilocalories, which is frequently referred to as one ton of oil equivalent.” 1 mto[e] generates 4.4 terawatt-hours “in a modern power station.”