01 1 Chapter1 Origin & HC properties [Compatibility Mode] CHAPTER 1 ORIGIN & PROPERTIES OF HYDROCARBON 1 THE ORIGIN OF PETROLEUM 2 REQUIREMENTS FOR PETROLEUM ACCUMULATION 3 PETROLEUM CHEMISTRY 4 PHYSI[.]
CHAPTER 1: ORIGIN & PROPERTIES OF HYDROCARBON THE ORIGIN OF PETROLEUM REQUIREMENTS FOR PETROLEUM ACCUMULATION PETROLEUM CHEMISTRY PHYSICAL and CHEMICAL PROPERTIES OF CRUDE OIL CLASSIFICATION AND OCCURRENCES OF CRUDE OIL ALTERATION OF CRUDE OIL GAS PROPERTIES AND CLASSIFICATION THE ORIGIN OF PETROLEUM • THEORIES OF INORGANIC ORIGIN – Hypothesis of Dimitri Mendeleev – Hypothesis of Sokoloff • THEORY OF ORGANIC ORIGIN • Analogy with organic matter • Biomarker • The present of porphyrins • The polarization of ray-light • Evidence of carbon isotopes EVIDENCE OF CARBON ISOTOPES • • • • • • • Delta values (d 13C) Carbon of mantle derivation -2 to -20 (Magmatic rocks, volganic gas, diamonds, and carbon in precambrian rocks or in meteorites) Carbon in organism or organic matter -15 to -30 Marine plants and invertebrates (no bone) -12 to -30 Land plants, coal and soil humus -23 to -28 Crude oils -22 to -36 Associated petroleum gas -35 to -55 Nonassociated petroleum gas -45 to –65 Standard 13C -notation, where, d 13C = [((13C/12C)sample/(13C/12C)standard) – 1]x1000 The d 13C values are reported relative to the V-PDB standard Requirements for Petroleum Accumulation The task of finding a petroleum field is not a simple one • First, there must be a rock containing original organic matter-a source rock Usually this is a mudrock or shale, which is a very common rock type and makes up about 80% of the world's sedimentary rock volume However, even an average shale contains only about 1% to 2% organic matter, and this number can vary widely Many shales have very low organic content and make poor source rocks • Then, the source rock must be buried deeply so that temperature and time can cause the organic matter to mature into petroleum This usually requires deposition into sedimentary basins, depressed areas thickly filled by sediments Our search for petroleum is further limited, since over half of the world's continental areas and adjacent marine shelves have sediment covers either too thin or absent Requirements for Petroleum Accumulation (cont) • Even where the organic matter can become mature, not all of it becomes petroleum In a typical example (Figure 01) a normal marine shale with only 1% original organic matter will have less than a third of it converted to the hydrocarbon molecules that make up oil and natural gas (Waples, 1981) The rest remains behind as an insoluble organic residue Figure 01 Requirements for Petroleum Accumulation (cont) • Five factors, therefore, are the critical risks to petroleum accumulation (Figure 02): (1) a mature source rock, (2) a migration path connecting source rock to reservoir rock, (3) a reservoir rock that is both porous and permeable, (4) a trap, and (5) an impermeable seal And • Last one is timing • If any one of these factors is missing or inadequate, the prospect will be dry and the exploration effort will be unrewarded Not surprisingly then, less than half of the world's explored sedimentary basins have proved productive, (Huff, 1980) and typically only a fraction of 1% of the petroleum basin's area, and at most 5% to 10%, is actually prospective (Weeks, 1975) Figure 02 PETROLEUM CHEMISTRY • Strictly speaking, hydrocarbons are compounds that contain only two elements, hydrogen and carbon Consequently, petroleum is quite simple in its elemental composition It contains relatively few impurities, mainly atoms of nitrogen, sulfur, and oxygen