These are liquid hydrocarbons that notation varying amounts of dissolved gases, bitumen’s, and other impurities. In the raw state, crude oil resembles ordinary lubricating oil. It is immiscible with water and has a density less than that of sea water thus, crude oil floats on water. Crude oil is however, soluble in naphtha, carbon disulfide, ether, and benzene. Thick crude oil. Lighter crude oil Very light crude oil. Petroleum in solid state at room temperature Figure 1 2. Natural gas is petroleum gas as distinguished from manufactured gas.
Natural gas consists of lighter paraffin hydrocarbons (hydrocarbons of the methane series), the cost abundant being methane gas (CHI). 3. Semi, and solid forms are called heavy hydrocarbons and bitumen’s. They comprise materials such as asphalt, tar, pitch, liberate, or any number of names depending on their individual characteristics and local usage. NATURE OF PETROLEUM The basic components of petroleum and natural gases are mixtures of hydrocarbons, carbon and hydrogen being the only elements essential to their composition.
A great number of hydrocarbons occur in nature while even more organic and synthetic hydrocarbons are routinely prepared in the laboratory and in chemical plants. The components of crude oil can be classified into two hydrocarbon series: methane series and the naphthalene series. Ethane CASH Butane SOCIO Figure 2 Benzene CASH 2 Crude oil belonging to the methane series is also referred to as paraffin. Paraffin are straight-chain hydrocarbons having a general formula of Cohn+2.
The four principle types of paraffin are methane (CHI), ethane (CASH), propane (CASH), and butane (SOCIO) with each heavier molecule adding one CHI molecule to the preceding compound. Another type of crude oil is that belonging to the naphthalene series. It contains carbon ring compounds having the general formula Cohn. These are called Californians with the most common being cyclopean (CASH) and cyclopean (CASH). However, the molecular structures for this group of hydrocarbons can contain long, branched chains with complex rings, such as C30H500H.
Of the two types of crude oil, paraffin or methane series oil is the most prized, but it comprises less than 2% of the total world supplies. Cruder dominated by naphthalene components are called asphalt-based oils. About 15% of the total world supply of crude is this type; it is also called the black oil. However, the vast majority of crude oils are a mixed base of some combination of paraffin and naphthalene. Natural Gas consists of hydrocarbons not condensable at atmospheric temperatures (OFF) (ICC) and atmospheric pressure. Natural gas comprises the first four members of the paraffin series.
If the natural gas is comprised almost entirely of methane, it is referred to as dry gas. But if the ethane content in methane exceeds 5%, it is referred to as a wet gas. There are three (3) distinct types of natural gas based upon their origin: 1. Petroleum gas – formed as a natural by-product during the generation of petroleum. It is often dissolved within the liquid hydrocarbon or in a free gas phase associated with the oil pool. 2. Coal gas – formed by the modification of coal through the introduction of heat, pressure or other natural processes. Coal gas is the source of most of world’s supply of commercial natural gas.
And, 3. Bacterial gas – forms during the low temperature alteration of organic matter at or near earth’s surface. Bacterial gas has no direct correlation with petroleum; a type of bacterial gas is marsh gas which forms in stagnant waters containing decomposing vegetation. Mineral gas is a term restricted to the various asses given off during igneous activity, but this type of gas has no relationship to hydrocarbons. Liquefaction of natural gas can be induced by lowering the temperature significantly. Methane, for example, requires a temperature of -1600 C.
Petroleum, a mixture of carbon, hydrogen and oxygen, is rarely found in nature in a pure form without impurities. Of the three major impurities, sulfur, nitrogen, and oxygen, sulfur is seldom absent from crude oil and can be found even in minute the higher concentrations restricted to heavy crude. Some sulfur may be in elemental form in solution or as HAS (hydrogen sulfide). Crude containing hydrogen sulfide (HAS) is referred to as sour crude. High sulfur crude oil costs more to refine which meaner that future oil supply costs will increase the price paid for gasoline at the pump.
Moreover, compounding this problem, most refineries are not able to process the higher sulfur crude oil without major refinery modifications. Sweet crude is crude oil that contains less than 0. 1% sulfur but such deposits have declined significantly since sass’s. Sour gas refers to natural gas containing hydrogen sulfide (HAS). Similar restrictions apply to this type of natural gas as well. The HAS must be extracted urine processing of gas before the gas can be utilized by both industrial and domestic users.
Sour gas is typically found in carbonate reservoirs; concentrations greater than 100 pump are considered destructive because of the corrosive nature of HAS. 3 Nitrogen (N) is another major impurity in petroleum, though it is related primarily to asphalt content. Concentrations greater than 0. 02% N are considered high, but in petroleum removed from some areas of the world such as in parts of Europe, it can exceed 90%. Nitrogen must also be removed during refining process; this requires low temperatures. The nitrogen can be recovered, and often is, and used as an injecting in the secondary recovery of light oils.
Oxygen is the third major impurity found in petroleum. Oxygen compounds in crude oil form acids while such compounds in natural gas are in the form of carbon dioxide (CO). The latter is, in itself, a natural gas, but it is non-combustible. Concentrations of oxygen vary widely: Some gas fields in the United States (Utah, Wyoming) for example, contain greater than 90% CO. Excess oxygen must be removed during processing and refining. Another major impurity found in petroleum is heavy metals. These are primarily Vanadium and Nickel and are the most unusual constituents of crude oil.
Vanadium, a high strength alloy in steel, is the most common and is found in concentrations typically varying from 30 1100 pump. Venezuela crude contains more vanadium (by volume) in its crude oil than total world demand for the alloy. Burning the crude oil yields a vanadium-rich ash. Vanadium is generally associated with high sulfur content (HAS) petroleum. Nickel, the second heavy metal impurity, is generally associated with crude that is low in sulfur content. Both impurities, vanadium and nickel, must be removed during the refining process.
The physical properties of petroleum: The physical properties of petroleum are controlled by the chemical composition. The most readily observed parameters are: specific gravity, viscosity, and color. Specific Gravity is defined as the ratio between weight of a given volume of material and weight of an equal volume of water at 40 C. Oils generally lie between 0. 73 – ?>1. 0 with paraffin-based oils being commonly light. Conversely, asphalt-based (naphthalene components) oils are almost always heavy. The units of measure are degrees and are read directly from a hydrometer.