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Unformatted text preview: Components of Petroleum Fluids
PETR 3302 August 28th Basic Organic Chemistry Organic Chemistry: Chemistry of compounds of carbon Carbon compounds usually stable because of the strength of the carboncarbon bond and can be chain forming Structural theory concerned with the way atoms are combined to form molecules Homologous series members have similar molecular structure Chemical Bonds Ionic Bond: transfer of electrons from one atom to another Chemical Bonds Covalent bonds: Atoms share electrons to fill their outer shells (carbon's outer shell can hold 8 electrons) Sharing of two electrons single bond, sharing of four electrons double bond, six electrons triple bond, etc. Lewis diagram Homologous Series Aliphatics Aromatics Alkanes Alkenes Alkynes Cyclic aliphatic Alkanes Also known as paraffins or saturated hydrocarbons Formula: CnH2n+2 Methane, Ethane, Propane, etc. nnormal or continuous chain, e.g. nbutane (other prefixes or naming conventions indicate isomers) Unreactive, and show a smooth dependence of physical properties on the number of carbon atoms Some physical properties of the nalkanes
Note: The chemical formula is written differently to show structure Alkenes Also known as unsaturated hydrocarbons or olefins Formula: CnH2n Distinguishing feature: a carboncarbon double bond (compounds with multiple cc double bonds also exist) Simplest member, C2H4 is ethene or commonly, ethylene, C3H6 is propene or commonly, propylene More reactive than alkanes Alkynes These have a carboncarbon triple bond Formula CnH2n2 CH CH is the simplest possible alkyne, and by convention, is named ethyne, however, it is known as acetylene. Alkynes are more reactive than alkenes or alkanes (single bond is most stable, double bond slightly less stable, triple bond even more unstable) Ring or cyclic compounds Cycloalkanes (cyclic aliphatics), also known as the naphthenes, have a saturated ring and the formula CnH2n if there are all single bonds between the carbons Benzene: Flat molecule with six carbon atoms arranged in a hexagonal ring. First thought to be an alkatriene (cyclic aliphatic with a triple bond) but was found to be much more stable (termed an aromatic because of its pleasant smell) Benzene Toluene an aromatic used as a solvent Other compounds Nonhydrocarbons: nitrogen, Carbon dioxide, hydrogen sulfide Hydrogen sulfide (H2S) is a very poisonous gas (with a very strong odor), and is usually removed from natural gas by adsorption Exposure to lower concentrations can result in eye irritation, a sore throat and cough, shortness of breath, and fluid in the lungs. These symptoms usually go away in a few weeks. Longterm, lowlevel exposure may result in fatigue, loss of appetite, headaches, irritability, poor memory, and dizziness. Higher concentrations of 700800 ppm tend to be fatal. Sour Gas (Hydrogen Sulfide) 0.0047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic rotten egg odor of hydrogen sulfide  1020 ppm is the borderline concentration for eye irritation. 50100 ppm leads to eye damage. At 150250 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger, 320530 ppm leads to pulmonary edema with the possibility of death. 5301000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing; 800 ppm is the lethal concentration for 50% of humans for 5 minutes exposition ( LC50). Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath. A practical test used in the oilfield industry to determine whether someone requires overnight observation for pulmonary edema is the knee test: if a worker that gets "gassed" loses his balance and at least one knee touches the ground, the dose was high enough to cause pulmonary edema. This is important as the worker may feel fine after some fresh air, and not think medical attention is needed, but the onset of pulmonary edema may occur many hours later when the worker is asleep: the worker's lungs could fill with fluid, and the sedative effects of the gas may prevent the Resins and Asphaltenes Large molecules, primarily hydrocarbon, with 13 sulfur, oxygen or nitrogen atoms per molecule Asphaltenes do not dissolve in petroleum, resins dissolve easily in petroleum Resins are heavy liquids or sticky solids Asphaltenes are dry, solid, black powders ...
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This note was uploaded on 09/21/2008 for the course PTEC 502 taught by Professor Sue during the Spring '08 term at University of Texas Medical Branch at Galveston.
- Spring '08