The more oil prone a kerogen, the higher its quality. This page has been accessed 95,211 times. The formation of geopolymers in this way accounts for the large molecular weights and diverse chemical compositions associated with kerogen. Type III kerogens are derived from terrestrial plant matter, specifically from precursor compounds including cellulose, lignin (a non-carbohydrate polymer formed from phenyl-propane units that binds the strings of cellulose together); terpenes and phenols. This breakdown process can be viewed as the reverse of photosynthesis. When we compare hydrocarbon generation curves and transformation ratio curves from 1-D models, we can develop a relationship in a way similar to that for generation-maturity. Kerogen types. [7] These resulting units can then polycondense to form geopolymers. Sapropelic kerogen is formed through NMR experiments have found that carbon in kerogen can range from almost entirely aliphatic (sp3 hybridized) to almost entirely aromatic (sp2 hybridized), with kerogens of higher thermal maturity typically having higher abundance of aromatic carbon. Kerogens are described as Type I, consisting of mainly algal and amorphous (but presumably algal) kerogen and highly likely to generate oil; Type II, mixed terrestrial and marine source material that can generate waxy oil; and Type III, woody terrestrial source material that typically generates gas. [29][30][31] This evolution is consistent with the change in carbon speciation from predominantly aliphatic (similar to wax, density < 1 g/ml) to predominantly aromatic (similar to graphite, density > 2 g/ml) with increasing thermal maturity. Thermally immature samples were used to provide a complete understanding of changes in GOR from incipient petroleum generation through peak petroleum generation. Kerogen is insoluble in normal organic solvents in part because of its high molecular weight of its component compounds. It usually forms in stratified water columns of lakes, estuaries, and lagoons. Waples used the hydrogen index values (HI) to differentiate between the types of organic matter. 1. a) Explain the basic components of organic matter in sediments and different types of Kerogen in petroleum products. : New York, Springer-Verlag, 699 p. The best overall reference for petroleum geochemistry. kerogen. Different types of Kerogen contain different amounts of hydrogen relative to oxygen and carbon and thus control the type of hydrocarbon that will be generated in the sedimentary rocks in due course of time. Although pyrolysis of type II kerogen yields less oil than type I, the amount yielded is still sufficient for type II-bearing sedimentary deposits to be petroleum source rocks. Type III kerogens are characterized by low initial H/C ratios and high initial O/C ratios. ... Organics to petroleum - zooplankton; 'sapropel'; fats, resinous, waxy. Analyses of kerogen are generally performed on samples prepared by acid demineralization with critical point drying, which isolates kerogen from the rock matrix without altering its chemical composition or microstructure.[6]. In most cases, the kerogen is separated from the rock [11], but some attempts to examine bulk rock were also undertaken [12, 13]. Prauss, M., and W. Riegel, 1989, Evidence from phytoplankton associations for causes of black shale formation in epicontinental seas: Neues Jahrbuch fur Geologie und Palaontologie, Monatshefte, v. 11, p. 671-685. We know from the hydrocarbon generation-maturity relationship that at 2.6 km2,600 m 8,530.184 ft 102,362.26 in this well has a vitrinite reflectance ( Ro) of 0.7%. Geological burial processes cause clays to undergo physical and chemical alteration usually preceding the slow and systematic thermal conversion (generation) of kerogen to petroleum. [32] These results indicate that all macerals decrease in oxygen content and increase in aromaticity (decrease in aliphalicity) during thermal maturation, but some macerals undergo large changes while other macerals undergo relatively small changes. Other kerogen types (and therefore their equivalent organic facies) are frequently mixtures of macerals. The first-order Raman spectra of kerogen comprises two principal peaks;[13] a so-called G band ("graphitic") attributed to in-plane vibrational modes of well-ordered sp2 carbon and a so-called D band ("disordered") from symmetric vibrational modes of sp2 carbon associated with lattice defects and discontinuities. [1] Kerogen may be classified by its origin: lacustrine (e.g., algal), marine (e.g., planktonic), and terrestrial (e.g., pollen and spores). [33], Type I kerogens are characterized by high initial hydrogen-to-carbon (H/C) ratios and low initial oxygen-to-carbon (O/C) ratios. These terms are reviewed in detail by Tissot and Welte (1978). As with other intermediate kerogen types, however, various maceral mixtures or degradational processes can contribute to kerogen type III formation. In addition, macerals that are richer in aromatic carbon are mechanically stiffer than macerals that are richer in aliphatic carbon, as expected because highly aromatic forms of carbon (such as graphite) are stiffer than highly aliphatic forms of carbon (such as wax). The mineral matrix effect occurs when polar clays react with polar organic molecules during the nonhydrous Rock-Eval procedure. [37] Such material is thought to have formed the terrestrial planets. Durand, B., 1980, Sedimentary organic matter and kerogen: definition and quantitative importance of kerogen, in B. Durand, ed., Kerogen: Techniq, p. 13–14. The table below lists and defines these four basic kerogen types. Well the generation of hydrocarbon type is given by a specific type of Kerogen. Appraisal and development are the key value areas for Zennor Petroleum and Pandion Energy—two producers owned by oil and gas-focused private equity (PE) firm Kerogen Capital—as well as the driving logic for the company to invest in AIM-listed Hurricane Energy. Kerogen type III contains sufficient hydrogen to be gas generative but not enough hydrogen to be oil prone. Nakamura, T. (2005) "Post-hydration thermal metamorphism of carbonaceous chondrites". The American Association of Petroleum Geologists is an international organization with over 38,000 members in 100-plus countries. Tissot, B. P., and D. H. Welte, 1984, Petroleum Formation and Occurrence, 2 ed. Bitumen forms from kerogen during petroleum generation. [10] As kerogen is a mixture of organic materials, it is not defined by a single chemical formula. Kerogen type II in its pure (monomaceral) form is characterized by the relatively hydrogen-rich maceral exinite. Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be produced, called shale oil (not to be confused with tight oil—crude oil occurring naturally in shales). Some mineral (polar clay) constituents retard the release of hydrocarbons from powdered whole rock samples during Rock-Eval pyrolysis, under-evaluating the quantity, quality, and thermal maturation data. These organic-walled microfossils have high H/C values because they formed hydrocarbons biologically. Time and temperature convert kerogen into petroleum. Some examples of pure assemblages with type I kerogen properties include the following: (1) the lacustrine alga Botryococcus braunii, which sometimes retains its diagnostic cup-and-stalk colonial morphology and/or its unique chemical compound, botryococcane;[13] (2) Tasmanites spp., which are low-salinity, cool water, marine algal phyto-plankton with unique physical features;[14] and (3) the Ordovician marine organic-walled colonial microfossil Gloeocapsomorpha prisca, with its diagnostic physical appearance and unique chemical signature. Diagenesis Francis, 2014 - There is a range of kerogen types, reflecting the type of original organic matter and the environment of deposition. This kerogen is rich in lipid-derived material and is commonly, but not always, from algal organic matter in lacustrine (freshwater) environments. matter. Complementary and consistent results have been obtained with infrared (IR) spectroscopy, which show that kerogen has higher fraction of aromatic carbon and shorter lengths of aliphatic chains at higher thermal maturities. gen type and thermal maturity during petroleum generation. Low content of polyaromatic nuclei and heteroatomic bonds. This type is either mainly derived from algal lipids or from organic matter enriched in lipids by microbial activity. The hydrogen to carbon ratio is originally high, and the potential for oil and gas generation is also high.-Type II kerogen. Peat. The gas-prone Type III kerogen with a lower initial hydrogen index falls slowly over a larger T max maturity range. The algae which remains in deep lakes (in anoxic conditions) is the major source of type 1 Source Rock. The type of kerogen present determines source rock quality. 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