Role of Organic Geochemistry in Petroleum

Role of Organic Geochemistry in embrocateA review on role of thorough geochemistry in fossil inunct color motion-picture show and maskings of diametric basinsHarish Chandra JoshiAbstract vegetable oil is a mixture dominantly of hydro hundreds with varying proportions of non-hydrocarbon constituents and traces of organometallic compounds. more often than not Petroleum has an average constitution of 85% carbon, 13% hydrogen, and 2% of sulphur, north and oxygen. The aim of study is to find out the physicochemical and genetic lieu of oil. In this study biomarkers, age specific biomarker and origin geochemistry coffin nail be use for the characterization, correlation and/ or reconstruction of the depositional environment as little and macro fossils used by the geochemist.Keywords Biomarker, Genetic Characterisation, Kerogen, Geochemical Fossils.IntroductionThe name geochemistry was offshoot used by the Swiss chemist, Christian Friedrich Schonbein in 1838. Petroleum geoche mistry is the application of chemical principles to the study of the derivation, migration, accumulation, and alteration of Petroleum ( unsanded and gun) and the use of this knowledge in exploring and recovering Petroleum. Organic chemistry is the branch of chemistry that deals with the distribution and composition of carbon compounds. Geochemistry is the study of the chemical composition of the earth, minerals, ores, careens and in any case is the study of the credit line of petroleum. The major tasks of geochemistry can be summarized as followsThe study of the relative and despotic abundances of the elements and of the atomic species (isotopes) in the earth.The study of the distribution and migration of individual elements in the unlike parts of the earth (the hydrosphere, atmosphere and lithosphere etc.), and in mineral and rocks, with the aspiration of discovering their distribution and migration.Exploration companies throw used petroleum geochemistry in hydrocarbon exp loration. The about and major objective of exploration geochemistry, is to reduce the risk of drilling switch over holes. Petroleum geochemistry is based on the organic origin of the inunct and gas whereby organic matter obtained from dead plants and animals. Organic matter is converted to hydrocarbons in the subsurface through various major common chord stages of transformations diagenesis, catagenesis and metagenesis. German scientist Treibs (1936) pick up a relationship between chlorophyll-a in spiritedness photosynthetic organisms and porphyrins in Crudes of petroleum. This link provides a strong evidence of organic originof Petroleum. From the commencement of the Precambrian till the Devonian, the unique primary make waterr of the organic matter were naval phytoplanktons. Since the Devonian an increasing amount of primary production has been contributed by higher(prenominal) cislunar plants. At present cenario marine phytoplankton and higher terrestrial ar estimate d to produce about equal amounts of organic carbon. On increases the burial depth, porosity and permeableness decrease, and temperature increases. Thus lead to the change a gradual halting of microbic activity and thus eventually called organic diagenesis to a halt. As the temperature rises, thermic reactions become increasingly. This second transformation phase, called catagenesis, during the catagenesis kerogen begins to decompose into smaller, more mobile molecules. In the early stage of catagenesis, kerogens be still relatively large these are precursors for petroleum and are called bitumen. In the late stages and final transformation stage, called metagenesis. During metagenesis the principal products consist of smaller gas molecules. Further, kerogens formed from different organic matter, or beneath different diagenetic conditions, are chemically sluttish which has a significant effect on hydrocarbon generation.Characterization of crude embrocate by Analytical MethodsFirs tly sampling of crude oils is required for their characterization. petroleum should be collected as a single- phase sample under pressure conditions as they are in reservoir. on that pointfore for the geochemical studies, crude oil samples are collected at the well head under atmospherical pressure. Under these conditions light hydrocarbons of crude oils are lost completely or partly. Light hydrocarbon fraction gives the ideas only about the abundance and constituents of the light intercept of the oil. It is normally observed that the or so abundant characteristics hydrocarbons are uncouthly in the light fraction. For required minimizing the effects of sampling error the crude oil is distilled at 2100C. The heavier fraction is considered the foremost part of the crude oil. It is used to expose the chemical composition of a crude oil and also to analyze it with other crude oils.Analytical Techniques in Petroleum ExplorationPetroleum system (Demaison, 1994 Hunt, 1996) comprise a ll those geological elements and processes that are necessary for an oil and gas deposit to occur in nature. These main elements are a petroleum reference book rock, migration paths, reservoir rocks, seals, traps and the geological approach that design separately of them. Such systems involve a genetic relationship between the radical rock and the petroleum accumulations, but proof of that relation force a geochemical correlation. organic geochemistry techniques available include surface geochemical prospecting, come rock geochemistry, crude oil geochemistry, natural gas geochemistry, biomarker geochemistry, isotope geochemistry etc.Biomarkers in Petroleumbiological marker or shortened to Biomarkers (Seifert and Moldowan, 1981) are complex molecules derived from once living organisms they are found in sediments and oil and show little change in structure from their parent molecules (Peters Moldowan, 1993 and Hunt, 1996). These compounds are also called as geochemical fossils (E glinton and Cavin, 1967) because of their origin from living organisms. Such compounds may be derived from terrestrial (mostly plants, marine pelagic (mostly plankton) and marine benthonic (algae, bacteria and other microbes). Biomarkers are generally, microfossils less than 30 nm in diameter and are highly variable in their stereochemistry i.e. the spatial arrangement of atoms and groups in their molecules.The common use of the biomarkers in petroleum exploration may be enumerated as followsBiomarkers are present in both and oil a reference rocks so they provide alert information for the oil-oil and oil-source correlation.Organic matter type (source of organic facies)Depositional environment fulfilment of thermal maturationDegree of biodegradationInformation about the age of the source rock and Geometry of BiomarkersSteranes obtain from the diagenesis of natural products sterols. Diagenesis converts sterol via chemical dehydration and microbial reduction to a steranes cholestan e. Cholestane molecule is drawn in three dimensions as follows. The hydrogen at the 3 position points up higher up the mat of the molecule and that at the 5 position points down below the planing machine (Peters and Moldowan 1993) jointly Used Biomarkers in Petroleum Exploration standard Alkanes no.mal alkanes are a homologues series of saturated hydrocarbons of general formula CnH2n+2. either linear n-alkanes from C1 to C40 and a few beyond C40 derived from different sources have been determine in crude oils.Iso- and Anteiso-alkanes Isoalkanes are 2-methyl alkanes and quite a number of these have been observed in crude oils as have been the anteiso-alkanes, the 3-methlyalkanes. Iso and anteiso alkanes are associated with n-alkanes in plant waxes where they comprise a approximate number of carbon atoms (about 25-31) with an bizarre predominanceFigure 1. Showing common biomarkers like paraffins, Iso and ante-isoalkaneAcyclic Isoprenoid These are special type of Iso-alkanes in which one methyl group is tie to every fourth carbon atom in straight. Isoprene (methyl butadiene) is the basic morphological unit composed of carbon atoms that is found in all biomarkers. The most common isoprenoids are pristane (C19) and Phytane (C20).Figure 2. Common Isoprenoid biomarkers in petroleumTerpenoids Terpenoids can be classified based on structural types into diterpenoids and triterpenoids Diterpenoids are categorise into bicyclic and tricyclic diterpenoids. Triterpenoids are grouped into tetra and pentacyclic. The most knowing are pentacyclic and among these are hopanes. Hopanes are pentacyclic triterpenoids comprised of four 6-membered and one 5-membered ring. There is a side chain which can contain upto 8 carbon atoms. Thus the series comprise of C27-C35 hopanes. They are believed to have originated from polyhydroxybacteriohopane.Figure 3. Structures of Common TriterpanesFigure 4. Structures of Common Tricyclic and Tetracyclic TerpanesSteranes Steroids can be cla ssified as aliphatic and aromatic steroids (mono, di- and tri-aromatic depending on the number of aromatic rings). Steranes are a series of aliphatic steroids. The sterols in all eukaryotic organisms are precursors to the steranes in sediments and petroleum. Like the hopanes, steranes are abundant in sediments, rocks and petroleum, because their precursors (Sterols) are so common in living organisms. Cholesterol has eight asymmetric centers and might be expected to show as many as 28 or 256 stereoisomers.Figure 5. chemic Structure of various steroidsPorphyrins Porphyrins are characterized by a tetrapyrrolic nucleus proved to be inherited from chlorophyll, the green photosynthetic key of plants and animals ,hemin, the red pigment of animal blood. These tetrapyrrolic organometallic compounds reported of the vanadium and nickel in petroleum. The major types of fossil porphyrin are deoxophylloerytrapyrrole (DPEP) and etioporphyrin (ETIO) porphyrin structure.Age specific biomarkersIf b iomarkers characterise a molecular record of life, they can be used for age determination. accepted age specific biomarkers like Oleanane present in oils derived from late cretaceous or Younger. C11-C19 Paraffins, Odd carbon number prevalence in oil from many Ordovician sources. 24-n-propylcholestane, High in oils from Ordovician sources.Thus the biomarkers transport to the sources has proved to be of smashing help in geochemical characterization of the oils/condensates. reference GeochemistryThe main aim of reservoir geochemistry is to understand the distribution and origin of the petroleum, water and minerals in the reservoir and placard for their possible spatial and compositional variation (Cubitt and England 1995). A better pinch of the fluids in the reservoir conduct to a better understanding in an area and prioritization of exploration thrusts. The principle factors responsible for difference in petroleum composition are the effect of organic facies variations, progressi ve source rock maturation, migration fractionation, gravity segregation, oil/water contact and non-uniform biodegradation of oil across the field. hitherto these effects have been normalized by using ratios of peaks corresponding to compounds of similar molecular weight in the C10+ region of the chromatogram.The study of reservoir continuity is also the focus of the geochemical characterization to trace the nature and depositional conditions of the source organics, identification of the oil families and thermal maturity date of the oils/condensates.When a set of chromatographic peaks has been selected, a variant of techniques are available for grouping of this data. One way is to use a polar plot of selected ratios by a star diagram (polygon plot) by plotting each peak ratio on a different axis of rotation of polar plot. Each data point is plotted from the centre of the homocentric circles outward. The points are then connected to create a star cause pattern characteristic of ea ch oil.Applications of geochemical characterisationBiomarker and non-biomarker geochemical parameters are best used together to supply the most authentic geological interpretations to help sack exploration, enlargement, production and environmental problems. Prior to biomarker work, oil and rock samples are mightily screened using non biomarker analyses. The strength of biomarker parameters is that they provide more detailed information postulate to answer questions about the source rock depositional environment, thermal maturity and the biodegradation of oils than non-biomarker analyses alone. divergent depositional environments are characterized by different assemblages of organisms and biomarkers. Commonly accept classes of organisms include bacteria, algae, and higher plants. Biomarker parameters are also an effective means to determine the relative maturity of petroleum through the entire oil-generative window.ConclusionOn the basis of above observation major conclusions wh ich have been derived from the whole study are as followsThe strawman of complete range of normal alkanes upto nC36 and in some cases upto nC40. The presence of biomarker in oil indicates that oil may be terrestrial or marine. The terrestrial nature of the source is also strongly indicated by the steranes. Reservoir geochemistry of oils has been used to demonstrate the lateral/vertical continuity/compartmentalization.ReferencesBhandari, A., Prasad, I.V.S.V., Kapoor, P.N., Varshney, Meenu, Madhavan, A.K.S., Pahari, S. and Singh, R.R., 2008. Depositional environment, distribution of source rocks and geochemistry of oil and gases, Krishna-Godavari Basin, Journal of Applied Geochem., Vol. 10 (1) pp 17-31Bhandari, A., Prasad, I.V.S.V., and Dwivedi, Prabhakar, 2007. Stratigraphic distribution of hydrocarbons in the aqueous Basins of India. Symposium in Applied Geochemistry in the evaluation and management of onshore and offshore Geo sources. Journal of Applied Geochemistry, Vol. 9 (1) p p 48-73.Bhatnagar, A.K., Goswami, B.G., Rawat, G.S., Singh, Harvir and Singh, R.R., 2009. Geochemical characterization and reservoir fingerprinting to respect reservoir continuity in oils of Heera and South Heera fields, western offshore basin, India, Petrotech 2009 stark naked Delhi.Cubitt, J.M., England, W.A., 1995. The Geochemistry of Reservoirs. The Geological Society London, pp 321.Demaison, G.J and Huizinga, B.J., 1994. Genetic classification of petroleum systems using three factors charge, migration and entrapment. In The Petroleum system From source to trap (L.B. Morgan and W.G. Dow, eds), American connectedness of Petroleum Geologists, Tulsa, pp. 73-89.Didyk, B.M., Simoneit, B.R.T.,Brassel, S.C and Eglinton, C., 1978. Organic Geochemical indicators of pale environmental conditions of sedimentation. Nature 272, pp 216-222.Eglinton, G and Calvin, M., 1967. Chemical fossils. Scl. Am. 216, pp 32-43Hunt, J.M., 1979. Petroleum Geochemistry and Geology. W.H. Freeman, San Franc isco, pp 617.Hunt, J.M., 1996. Petroleum Geochemistry and Geology. W.H. Freeman and Company, New York.Pandey, I.P., Joshi, H.C., Tyagi, Ashish Tiwari, Sadhana and Garg, Nitika, 2012. Study of the Parameters and Bio-Markers of Crude oils. Advances in Pure and Applied Chemistry, World Science Publisher, New York, United States, Vol. 1, No. 3, pp 49-53.Mackenzie, A.S., 1984. Application of biological markers in Petroleum Geochemistry, In Advances in Petroleum Geochemistry, Vol. 1, (J. Brooks and D.H. Welte, eds) Academic Press, London, pp 115-214.Mackenzie, A.S., Patience, R.L., Maxwell, J.R., Vandenbroucke, M and Durand B., 1980. molecular parameters of maturation in the Toarcian shales, Paris Basin, France-1. modify in the configuration of acyclic isoprenoid alkanes, steranes, and terpanes. Geochimicaetcosmochimica Acta, 44, 1709- 1721.Peters, K.E., 1997. Modern Geochemical Tools for efficient exploration and Development, O.G.C.I. teaching report, Oct. 20924, Mussoorie, India.Peter s, K.E. and Fowler, M.G., 2002. Application of Petroleum Geochemistry to Exploration and reservoir management. Org. Geochem. Vol 33, pp 5-36.Peters, K.E. and Moldowan, J.M., 1993. The biomarker guide interpreting Molecular fossils in petroleum and ancient sediments, Prantice Hall, Englewood Cliffs, NJ., U.S.A.Seifert, W.K. and Moldowan, J.M., 1978. Application of steranes, terpanes and Monoaromatics to the maturation, migration and source of oil. Geochem. Cosmochim., Acta 42, pp 77-95Seifert, W.K. and Moldown, J.M., 1979. The effect of biodegradation on steranes and Terpanes in crude oil. Geochem. Cosmochim., Acta 43, pp 111-126.Seifert, W.K. and Moldown, J.M., 1980. The effect of thermal stress on source rock quality as Measured by hopane stereochemistry.Physics and chemistry of the earth, 12, pp 229-237.Smith,H.M., 1940. correlation index to aid in interpretin crude oil analysis. U.S. Bureau of Mines, tech. piece of music610.Tissot, B.P. and welte, D.H., 1978. Pertoleum formatio n and Occurrence, Springer- Verlag, New York, pp. 699.Tissot, B.P and welte, D.H., 1978. Pertoleum formation and Occurrence, Springer- Verlag,Berlin.22.Treibs, A., 1963. Chlorophyll and hemin derivatives in organic mineral substances. Angewandte Chemie, 49, pp 682-686.1