FR2906482A1 - Hydrocarbon thermal cracking modeling by individualizing chemical classes of compounds, defining cracking reaction scheme, defining kinetic scheme, pyrolysis experiment and determining kinetic parameters and stoichiometric coefficients - Google Patents

Abstract

Modeling of thermal cracking of hydrocarbon, comprises: constructing reaction schemes of thermal cracking of kerogen, individualizing the chemical classes; defining a primary cracking reaction scheme of the kerogen; defining a scheme of secondary cracking reaction; constructing a kinetic scheme by determining the kinetic parameters and stoichiometric coefficients of the reaction scheme; conducting pyrolysis experiments; determining the proportions of pyrolysis products using a simulation; determining the kinetic parameters and stoichiometric coefficients and modeling the thermal cracking. Modeling of thermal cracking of hydrocarbon, comprises: (A) constructing reaction schemes of thermal cracking of kerogen, individualizing the chemical classes of: water, hydrogen sulfide and carbon dioxide; 1-4 carbon fraction; saturated hydrocarbons with more than 14 carbon atoms (C14+ fraction); nitrogen, sulfur and oxygen compounds (NSO); thermally inert polyaromatic solid; kerogen 1-4; fraction of saturated hydrocarbons with 6-14 carbon atoms (C14- fraction), alkylated, preferably methylated; saturated hydrocarbons with more than 14 carbon atoms (C14+ fraction) containing saturated C14+, aromatic hydrocarbons having more than 14 carbon atoms (Aro 1) and aromatic hydrocabons having more than 14 carbon atoms and resulting from thermal cracking of different families of hydrocarbon (Aro 2 and Aro 3); solid fraction containing polyaromatic solid resulting from thermal cracking of the aromatic fraction, preferably thermally reactive polyaromatic solid (prechar) (B) defining a scheme of primary cracking reaction of the kerogen, where each of the reactants decomposes into mobile and immobile products according to a table given in the specification (C) defining a scheme of secondary cracking reaction of the immobile NSO, immobile C14+ Aro 1, immobile C14+ Aro 2, immobile C14+ Aro 3 and prechar, where each of the reactants decomposes into mobile and immobile products according to a table given in the specification (D) constructing a kinetic scheme by determining the kinetic parameters and stoichiometric coefficients associated with the reaction scheme (E) conducting pyrolysis experiments to determine the proportion of pyrolysis products to each of the families of compounds such as non-hydrocarbon gases like carbon dioxide, hydrogen sulfide and water, hydrocarbon gases comprising 1-4 carbon atoms, liquid hydrocarbons, NSO compounds soluble in polar solvents, NSO compounds soluble in saturated solvents and solid residues containing kerogen 1-4 and prechar (F) determining the proportions of pyrolysis products for each of the families using simulation based on the reaction schemes (G) determining the kinetic parameters and stoichiometric coefficients using a numerical inversion by minimizing the difference between the proportion of the simulated products and the proportion of the paralyzed products (H) and modeling the kerogen thermal cracking using the kinetic scheme. An independent claim is included for a basin modeling in which the quantities of hydrocarbons present in source rocks and reservoir rocks are estimated using the thermal cracking modeling.

Description

The invention relates to the kinetics of thermal cracking of kerogens and

  associated petroleum products. Petroleum fluids are very complex mixtures of organic compounds.

  The main families of compounds are saturated hydrocarbons, aromatics, resins and asphaltenes. Saturated hydrocarbons form the majority group except in degraded heavy oils. This family includes n-alkanes, but also isoalkanes and cycloalkanes. The aromatic hydrocarbon family contains compounds of 1 to 5 aromatic rings, substituted by methyl or alkyl groups. The sulfur compounds of the oils include thiols, sulfides, thiophenes, benzothiophenes, dibenzothiophenes, naphthothiophenes, and bithiophenes. Resins and asphaltenes are molecules of high molecular mass containing heteroatoms: N, S and O, hence the name NSO. Crude oil may contain traces of metals. Vanadium can account for up to 75% of the metal content followed by nickel. The following nomenclature is used in the remainder of the description: The type of kerogen of type I, II, III, II is the geological types of kerogen known to those skilled in the art: type I kerogen, type II kerogen, kerogen of type III, Kerogen type They (containing sulfur). For the definition of type I, II and III kerogens, see Durand et al., 1972; Durand and Espitalié, 1973; and for Type II-S at Orr and Sinninghe Damsté 1986. In the following description, kerogen 1, kerogen 2, kerogen 3 and kerogen 4 will be used to denote the various chemical classes of kerogen determined for the implementation of the present invention. inside each geological type.

  The other chemical classes determined in the method according to the invention are: Cl: family of hydrocarbons with 1 carbon atom C2: family of hydrocarbons with 2 carbon atoms C3: family of hydrocarbons with 3 carbon atoms C4: family hydrocarbons with 4 carbon atoms C14-: saturated and unsaturated hydrocarbons having 6 to 14 carbon atoms aro BTXN: aromatic hydrocarbons of benzene, toluene, m-, p-, o-xylene, naphthalene aro alkyl type: other hydrocarbons alkylated aromatic compounds having 6 to 14 carbon atoms aromethyl: methylated aromatic hydrocarbons having 6 to 14 carbon atoms C14 + sat: saturated and unsaturated hydrocarbons having more than 14 carbon atoms 2906482 2 Aro 1: aromatic hydrocarbons having more than 14 carbon atoms Aro 2 and aro 3: aromatic hydrocarbons having more than 14 carbon atoms and resulting from the thermal cracking of different families of hydrocarbons.  Preload: polyaromatic solid resulting from the thermal cracking of the aromatic fraction, still hydrogenated, thus still thermally reactive.  Char: thermally inert polyaromatic solid.  Resins and asphaltenes are molecules of high molecular mass containing heteroatoms: nitrogen, sulfur and oxygen, they will be designated by NSO.  NSO1: Soluble NSO compounds in polar solvents, NSO2: Soluble NSO compounds in saturated solvents NSOS = NSO tot = NSO1 + NSO2 = resins + asphaltenes The invention relates more particularly to the processes of formation of oil and gas in sedimentary rocks, including the kinetics of thermal cracking of kerogen and associated petroleum products in source rocks: primary cracking and secondary cracking.  STATE OF THE ART The state of the art can be represented by the content of the bibliographical references below, to which the description refers.  Behar, F. , Ungerer, P. , Kressmann, S. , Rudkiewicz, J.  L. , 1991.  Thermal evolution of crude oils in sedimentary basins: experimental simulation in a confined system and 25 kinetic modeling.  Oil and Gas Science and Technology 46, 151-181.  Behar, F. , Vandenbroucke, M. , Tang Y. , Marquis F. , Espitalie J. , 1997.  Thermal cracking of kerogen in open and closed systems: determination of kinetic parameters and stoichiometric coefficients for oil and gas generation.  Organic Geochemistry 26, 321-339.  30 Durand B. , Espitalie J. , Nicaise N. , Combaz A. , 1972.  Study of the insoluble organic matter (kerogen) of the Toarcian clays of the Paris Basin.  I- Studies by optical methods, elementary analysis, study in microscopy and electron diffraction.  Oil and gas science and technology 27, 865-884.  2906482 3 Durand B. , Espitalie J. , 1973.  Evolution of organic matter during the burial of sediments.  Proceedings of the Academy of Sciences, 276, 2253-2256.  Espitalie J. , Laporte J.  L. , Madec M. , Marquis F. , Leplat P. , Paulet J. , Boutefeu A. , 1977.  5 Rapid method for characterizing source rocks, their petroleum potential and their degree of evolution.  Oil and gas science and technology 32, 23-42.  Horsfield, B. , Disko U. , Leibtner F. , 1989.  The micro scale simulation of maturation: outline of a new technique and its potential application.  Geologische Rundschau 78/1, 361-374.  10 Khorasheh, F. , Gray, M. R. , 1993.  High-pressure thermal cracking of n-hexadecane.  Industrial Engineering and Chemical Research 32, 1853-1863.  - Luo, L. vs. , Michael, G. E. , 1994.  A multicomponent oil-cracking model for modeling and composition of reservoir oil.  Organic Geochemistry 21, 911-925.  Lewan, M. , 1993.  Laboratory simulation of petroleum formation: Hydrous pyrolysis.  In: 15 Engel M. H. , Macko, S.  (Ed), Organic Geochemistry Principles and Applications, Plenum, New York, pp.  419-442.  Lewan M.  D. , Winters J.  vs. , Mac Donald J.  H. , 1979.  Generation of oil-like pyrolysate from organic rich shales.  Science 203, 897-899.  Lorant, F. , 1999.  Late genesis of hydrocarbon gases in sedimentary basins: kinetic and isotopic studies.  Thesis ENSPM-University of Strasbourg 1.  Lorant F. , Behar F. , Vandenbroucke M. , Mc Kinney D.  E. , Tang Y. , 2000.  Methane Generation from Methylated Aromatics: Kinetic Study and Carbon Isotope Modeling.  Energy and Fuels 14, 1143-1155.  25 Orr W.  L, Sinninghe Damsté J.  S.  (1990) Geochemistry of sulfur in petroleum systems.  In Geochemistry of sulfur in fossil fuels (Orr W.  L.  and White C.  Mr. ), pp.  3-29, ACS symposium series 429.  Tissot B. 1969.  First data on the mechanisms and kinetics of oil formation in sedimentary basins.  Simulation of a reaction scheme on a computer.  Oil and gas science and technology 24, 470-501.  Ungerer P. , Pelet R. , 1987.  Extrapolation of the kinetics of oil and gas formation from laboratory experiments to sedimentary basins.  Nature 327, 52-54.  Ungerer, P. , Behar, F. , Villalba, M. , Heum, O. R. , 1988.  Kinetic modeling of oil cracking.  Organic Geochemistry 13, 857-868.  2906482 4 Cracking of oils Thermal cracking is a radical mechanism that has been demonstrated by studying the cracking of hydrocarbons.  Studies have been conducted on some model compounds.  Thus work has been published on the cracking of n-hexane and n-hexadecane.  Studies have also been published on C25 n-alkane (n-pentacosane) as heavy paraffin model compounds (Behar and Vandenbroucke, 1996).  Finally, a theoretical model for calculating the overall cracking rates of n-alkanes from C3 to C32 has been proposed.  The family of cycloalkanes which represent an important chemical class of petroleum fluids has been studied very little in thermal kinetics.  Similarly, very little work has been published on the cracking of aromatic hydrocarbons.  Moreover, given the chemical complexity of this family, cracking mechanisms are far from known.  Information on apparent kinetic parameters was obtained from studies of ethylbenzene, n-butylbenzene, n-dodecylbenzene, alkylated polycyclic structures and 9-methylphenanthrene.  Tetralin (1,2,3,4-tetrahydronaphthalene) has also been studied as a representative model compound of the naphthenoaromatic family by many authors (Khorasheh and Gray, 1993).  A detailed kinetic scheme for the thermal cracking of tetralin has been proposed and the pyrolysis of 2-ethyltetralin has also been studied.  Pyrolysis of natural fractions of petroleum fluids has been the subject of some experimental studies (Ungerer et al. 1988; Kuo and Michael, 1994) in order to propose empirical global models of cracking.  An empirical model has been proposed for the cracking of oils from experimental data on 2 oils.  The kinetic scheme has 11 classes which includes 5 aliphatic classes (methane, ethane, (propane + butane), saturated C6-C14, saturated C14 +) and 6 aromatic classes (BTXN (Benzene + Toluene 25 + Xylene + Naphthalene), C9-C14 aromatics, unstable aromatic C14 +, more stable aromatic C14 +, precoke and coke).  In this model, in order to reduce the number of classes, the same frequency factor was applied for all unstable chemical classes.  In addition, each reaction is mono energetic.  This highly simplified model is not very predictive and could not be used to report the composition observations of petroleum fluids that have undergone intense thermal cracking in natural reservoirs.  A modified version has been published more recently, but it still has very large uncertainties; in particular, this model does not restitute the respective quantities of gases and oils present in the natural reservoirs and the liquid fraction is too enriched in aromatic structures with respect to the natural fluids.  An attempt to develop real kinetic schemes on a complex mixture of 2906482 model compounds has been published.  This scheme after lumping has 5000 reactions.  The model accounts for the cracking of a mixture of 52 paraffin-dominated molecules: 30 linear alkanes (from CH4 to C30H62), 10 branched alkanes (including pristane and phytane), 2 naphthenes (propylcyclopentane and propylycyclohexane), tetralin, 1-methylindan, aromatic (benzene, toluene, butylbenzene and decylbenzene), 3 heteroatomic compounds (di-isopropyl disulfide, isopropyl mercaptan, and H2S) and naphthalene.  A globalization by the "lumping" of species was carried out to reduce the size of the system of elementary reactions.  The "lumping" method used consists in grouping all functional isomers into a pseudo-compound.  The model thus comprises 5200 processes.  The model is centered mainly on the pyrolysis of alkanes, the cracking of which is presented in the model by '/ 2' reactions with activation energies of approximately 70 kcal / mol.  The role of the alkylaromatic and naphthenoaromatic compounds in the model is the inhibition of pyrolysis of alkanes by formation of the radicals stabilized by resonance.  Aromatic compounds are under-represented in the model and their cracking is limited to average conversions.  Heavy compounds: resins and asphaltenes are not taken into account in the model.  On the other hand, the simple sulfur molecules used in the (disulfide, mercaptan) model are not representative of this class in real oils, which mainly comprise aromatic sulfur compounds whose thermal behavior has not yet been elucidated (thiophene, benzothiophene, dibenzothiophene, naphthenothiophenes).  In conclusion, at present the available data are either precise studies on model compounds, or limited or poorly predictive studies on petroleum fluids or fractions of petroleum fluids.  Also an originality of the method according to the invention concerning the cracking of petroleum products, is to propose a scheme by a limited number of global chemical classes and to constrain the determination of global kinetic parameters with those obtained on model compounds.  With particular reference to cracking of kerogen, it is recognized that the process of formation of oil and gas in sedimentary basins is the result of a thermal cracking of organic matter, called kerogen, present in source rocks.  Thermal cracking reactions occur in natural systems at temperatures between 80 and 200 C for times up to several million years.  Since these reactions can not be reproduced under the same conditions in the laboratory, it is necessary to carry out experiments at higher temperatures (300-600 ° C.) and for reasonable times (a few minutes to a few hours).  For each of the reactions considered, the degradation rates observed at different temperatures in the laboratory make it possible to define laws of variation as a function of time and temperature, and by extrapolation to evaluate the rates of these same reactions in natural systems.  Kerogen is a complex mixture of very high molecular weight macromolecules and is insoluble in common organic solvents.  It is possible to study its thermal cracking either in open reactors (Rock Eval technique) or in closed reactors (Horsfield et al. , 1989, Behar et al. 1989) or in closed reactors in the presence of water (Lewan et al. 1979; Lewan 1993).  Although involving physicochemical mechanisms of extreme complexity, the thermal cracking of kerogen obeys globally the principles of chemical kinetics.  The combined effects of time and temperature on the rate of transformation of kerogen into hydrocarbons have been demonstrated for a long time.  Experimentally first, with the pioneering work of the 1930s showing that the formation of oil from kerogen is all the faster as the temperature is high.  These studies have also highlighted the existence of a first-order relationship between the amount of hydrocarbons formed and their production rate.  It was not until much later in the 1960s and 1970s that these principles, issued 30 years earlier, were validated by observations.  Inspired by both the reactivity models of polymers and the approaches developed by German coalmakers in the late 1940s, the first models of primary cracking in oil parent rocks appeared in the 1960s.  Several approaches for the thermal conversion of kerogen to oil and gas have been developed and described in the literature.  These models can be grouped according to two kinds of reaction schemes: - The models with consecutive reactions (a): the formation of hydrocarbons in the source rocks does not result from the direct decomposition of the kerogen, but from a series of 30 successive transformations transforming kerogen in a viscous, thermally labile phase (called, according to the authors, either mesophase, bitumen, or NSO), which in turn decomposes into oil and gas (Tissot, 1969).  Each reaction is assumed to be mono-reactive, of order 1, and the rate constants are given by the Arrhenius law.  - Models with parallel reactions (b): here the petroleum potential of a source rock is described by means of independent competitive reactions of order 1, whose speed constants are provided by the law of Arrhenius.  The reactions are each characterized by a specific activation energy, set in advance, a pre-exponential factor (the same for all reactions), and a fraction of the petroleum potential.  These fractions, corresponding to the contribution of each reaction to the total petroleum potential, are defined according to the energies of activation, either independently of each other by means of a discrete distribution (Ungerer and Pelet, 1987), or constrained by means of a continuous function.  In all cases, the kinetic and stoichiometric parameters associated with the cracking reactions are usually calibrated by means of pyrolysis experiments carried out at high temperature (300-700 C) for times ranging from a few minutes to a few weeks.  The empirical models thus obtained are merely simplistic representations of the kerogen oil balance as a function of time and temperature.  Extrapolated at low temperature, they nonetheless make it possible to estimate the geological period during which hydrocarbons were formed in a source rock.  The application that is made of these kinetic models in numerical simulation of the 20 sedimentary basins requires a precise and geologically realistic parameterization.  However, it has been observed that depending on the way in which the pyrolysis experiments are carried out in the laboratory (open environment, closed medium, with or without the addition of water), the kinetic parameter values obtained from the same kerogen are very variable. .  This is true regardless of the model (a) or (b) assumed, that is to say that each kinetic model only represents the dataset from which it was calibrated.  This leads to the conclusion that neither approach satisfactorily models the transformation of kerogen into hydrocarbons, as the experimental differences are not elucidated by the proposed chemical mechanisms.  Regardless of the pyrolysis system, the pyrolysis products obtained during thermal cracking of kerogen include both hydrocarbon and non-hydrocarbon gases, saturated and aromatic hydrocarbons and organic compounds soluble in organic solvents and which contain oxygen, nitrogen and sulfur.  All of these products are generally called "NSO compounds".  They are of high molecular weight.  The main difficulty in studying the thermal cracking of kerogen is that the chemical composition of the kerogen or reagent is not known.  Only global analyzes and chemical or thermal degradation techniques make it possible to obtain structural information without having access to the identification of the constitutive molecules of the kerogen.  Thus, the most commonly used approach is to follow the nature of the products formed and to make a mass balance between the residual reagent and the mass of the products.  A second difficulty is to link the reaction bonds between the nature of the products formed and the starting reagent; some products in fact, which can in turn undergo thermal cracking and generate new constituents (secondary cracking).  Finally, a third difficulty is the implementation of various analytical protocols appropriate to the characterization of the products formed.  Thus, the method according to the invention proposes, on the one hand, a model of primary thermal cracking of kerogen and a secondary cracking model making it possible to solve the above-mentioned problems.  On the other hand, the invention provides a kinetic scheme of thermal cracking of petroleum products comprising a limited number of global chemical classes and wherein the determination of overall kinetic parameters is constrained by those obtained on model compounds.  The method according to the invention The invention relates to a method for modeling the thermal cracking of at least one type of kerogen.  The method comprises the following steps: individualizes at least the following chemical classes: • H20, H2S, CO2 • kerogen 1, 2, 3 and 4 • Cl, C2, C3, C4 • C14_ sat, C14_alkyl, C14-methyl • C14 + sat • C14 + Am-1, 2, 3 • NSOs • prechar • char 25 a.  b.  a reaction scheme is defined for the primary cracking of at least one type of kerogen, in which it is required that each reagent be decomposed into mobile products (m) and immobile products (im) according to the following table: reagents -> mobile products + stationary products kerogen 1 -> H2O, H2S, 002 C14 + Arol- im C1, C2, C3, C4 NSOs im C14_ sat, C14_ alkyl, C14_ methyl kerogen 2 C14 + sat, C14 + Aro-1 m, NSOs m kerogen 2 - > C1 1 + kerogen 3 kerogen 3 -> C1 kerogen 4 c.  a reaction scheme is defined for the secondary cracking of immobile NSOs, immobile C14 + Aro-1s, immobile C14 + Aro-2s, immobile C14 + Aro-3s and prechar, in which it is required that each reagent be decomposed into mobile products and immobile products according to the following table: reagents ---> mobile products + immobile products NSOs im ---> H2O, H2S, CO2 prechar Cl, C2, C3, C4 C14_ sat, C14_ alkyl, C14_ methyl C14 + sat, C14 + Aro- 1 m, NSOs m C14 + Aro-1 im -> H2S C14 + Aro-2 im C1, C2, C3, C4 C14_ sat, C14_ alkyl, C14_ methyl C14 + sat, C14 + Aro-2m C14 + Aro-2 im -> C1 + prerequisites • C14 + Aro-3 im C14 + Aro-3 im! According to the method, it is possible to define a kinetic scheme by determining the kinetic parameters and stoichiometric coefficients associated with said reaction schemes, by performing the following steps: d.  pyrolysis experiments are carried out to determine proportions of pyrolysis products for each of the following families of compounds: non-hydrocarbon gases: 002, H2S, H2O hydrocarbon gases comprising 1 to 4 carbon atoms hydrocarbon compounds NSOs1 and NSOs2 10 solid residues: kerogen 1, kerogen 2, kerogen 3, kerogen 4, prechar e.  pyrolysis product proportions are determined for each of said families of compounds using a simulation based on said reaction schemes according to steps b and c; and F.  said kinetic parameters and said stoichiometric coefficients are determined by means of a numerical inversion in which the difference between said proportions of pyrolysis products simulated in step e) and said proportions of pyrolysis products resulting from the pyrolyses at step d).  Advantageously, a digital simulator is used which resolves speed laws of said reactions of said kinetic scheme as a function of time and temperature.  In the method, the cracking reactions can be characterized by activation energy distributions, EE1 and EE2, and by activation energies, E3 and E4, as well as by stoichiometric coefficients, X, at X7, Y, at Y4, Z ,, Z2, W, and W2 according to the following kinetic reaction scheme: EE, Kerogen 1 X, non HC gas + X2 HC + X3 C, 4 + Aro im + X4 C, 4 + Aro m + X5 NSOs im + X6 NSOs m + X7 kerogen 2 EE, NSOs im - X, non HC gas + X2 HC + (X3 + X4) C, 4 + Aro m + (X5 + X6) NSOs m + X, prechar NSOs m EE2 Y, non HC gas + Y2 HC + Y3 C14 + Aro m + Y4 prechar Kerogen 2 E3 Z1 C, + Z2 kerogen 3 Kerogen 3 E4 W, C, + W2 kerogen 4 and in which non-gas HC represents non-gas hydrocarbons and HC represents hydrocarbon gases.  The method can be applied to basin modeling in which the amounts of hydrocarbons present in the source and reservoir rocks are estimated using the method.  Advantageously, a rate of transformation of the kerogen is measured from pyrolysis experiments, then a rate of transformation of the kerogen is determined from said reaction kinetic scheme, and a correction to be applied to the measured transformation rates is deduced therefrom. , in order to define the expulsion episodes of hydrocarbons as well as the composition of said hydrocarbons.  Finally, it is possible to reduce the size of the reaction scheme according to the conditions required by a field of application, by reducing the number of chemical classes by grouping said chemical classes.  Brief Description of the Figures - Figure 1 shows the approach taken to obtain the lumped reaction scheme for cracking oils or secondary cracking in the tank.  FIG. 2 represents the approach adopted to propose a reaction scheme for primary and secondary cracking of the kerogen according to the invention.  FIG. 3 represents the successive and parallel cracking reactions of the primary and secondary cracking reaction scheme according to the invention.  FIGS. 4A to 4C show kinetic TR and natural TR abacuses for the four initial kerogens studied.  FIG. 5 represents the successive and parallel cracking reactions of the hydrocarbon thermal cracking reaction scheme according to the invention.  DETAILED DESCRIPTION OF THE INVENTION The invention provides for the development of kinetic cracking schemes of organic matter in source rocks that include not only the cracking of kerogen (primary cracking), but also that of the NSO compounds generated therefrom. kerogen (secondary cracking).  Thus the fluid expelled from the source rock is the result of the cracking of kerogen and that of NSO compounds.  This approach therefore corresponds to a coupling between the two concepts previously described and schematized in FIG. 2 which describes the approach adopted to propose a reaction scheme for primary and secondary cracking of the kerogen according to the invention in which: K Kogenogen (Type I, II, III, II) B Intermediate heavy product (Bitumen, Mesophase, NSO, etc.) ) HC: Hydrocarbons 20 Xi • Stoichiometric coefficients.  An original approach of the present invention is: - to establish mass balances and complete atomic balances on the elements present in the initial kerogen (kerogen of type I, II, III and They) ie carbon, of Hydrogen, oxygen and sulfur on all the pyrolysis products (gas, liquid and solid).  to give a detailed description of the pyrolysis products in: • Non-hydrocarbon gases: CO2, H2S and H2O • Hydrocarbons: Cl, C2, C3 and C4, 30 • C6-C14 methyl aromatic hydrocarbons, C6-C14 alkyl aromatics, BTXN Saturated C6-C14, saturated C14 +, aromatic C14 + 1, aromatic C14 + 2, aromatic C14 + 3.  • the compounds NSOs 1 and NSOs 2 2906482 13 • solid residues kerogen 1, kerogen 2, kerogen 3, kerogen 4 and prechar and char.  The choice of these classes and the determination of their proportion in the pyrolysis product mixture results from the parameter acquisition method described above.  - The detailed monitoring of these different classes according to the conversion of kerogen allows to develop a coherent kinetic scheme that includes parallel and successive reactions.  These reactions can be described by activation energy distributions and mono energetic reactions (Figure 3).  The nomenclature of the chemical compounds is described at the beginning of the description.  As indicated, this kinetic scheme also includes secondary cracking reactions of kerogen cracking products such as NSO compounds 1 and 2.  Indeed, as mentioned above, NSOs 1 and 2 are thermally unstable under laboratory and geological conditions: also a cracking reaction of these compounds has been introduced.  On the other hand, aromatic C14 + 1 are also thermally unstable and undergo secondary cracking and generate aromatic C14 + 2 which in turn will produce aromatic C14 + 3.  Two solid phases are indicated in this kinetic scheme: the prechar and the kerogen 2.  Lekerogen 2 is the portion of kerogen 1 that has not been converted and the prechar is the solid residue formed during cracking of NSO compounds.  An earlier study on the thermal cracking of kerogen 2 (Lorant, 1999, Lorant and Behar, 2000) has made it possible to propose a specific kinetic scheme in two successive reactions.  From this integrated scheme, it is possible to define relative proportions between mobile and immobile compounds for certain chemical families in particular for aromatic C14 + 1 and compounds NSOs 1 and NSOs 2.  Typically NSOs 1 compounds of very high molecular weight can be considered to be predominantly immobile in source rocks.  For weight NSOs 2 compounds, a larger portion is mobile.  The relative proportions of immobile and mobile compounds for these 2 families can be adjusted case by case.  Thus the use of this new kinetic scheme allows, for the first time, to account not only for the nature of the liquid, gaseous and solid products generated during the cracking of kerogen under laboratory conditions and in geological conditions, but also the composition of the fluids actually expelled out of the source rocks.  The whole kinetic scheme is summarized in Table 1: initial kinetic pattern initial mobile products E products immobile kcal / mol kerogenic primary cracking 1 H20, H2S, CO2 C14 + Aro-im kerogen distribution 2 Cl, C2, C3, C4 NSOs ims mono kerogen 3 C14_ sat, C14_alkyl, C14. .  methyl kerogen 2 mono C14 + sat, C14 + Aro-1m, NSOs m kerogen 3 C1 kerogen 4 C1 cracking NSOs im H20, H2S, CO2 prechar secondary distribution C14 + Aro-1 im Cl, C2, C3, C4 C14 + Aro-2 distribution C14_ sat C14_alkyl, C14_methyl C14 + sat, C14 + Aro-1, NSOs m H2S C1, C2, C3, C4 C14_salt, C14_alkyl, C14_methyl C14 + sat, C14 + Aro-2 ----------- -------------------------------------------------- ---------------------------------------- C14 + Aro-2 im C1 C14 + Aro-3 mono ------------------------- prechar C14 + Aro-3 im ------------------ ------- prechar ------------------------------------------ --------------------------- --C1 prechar mono ------------------ -------------------------------------------------- -------- C1 mono tank Table 1: Kinetic scheme for the cracking of kerogen and description of the composition of the products formed as well as the secondary cracking reactions of the immobile products.  This new kinetic scheme explains the experimental results obtained during simulations in an open environment, closed without water and closed with water.  In the particular case of open thermal cracking simulations, not all NSO compounds are removed from the pyrolysis chamber because of their high molecular weight.  Thus some of them, once generated, remain in the pyrolysis chamber and undergo thermal cracking at the same time as the initial kerogen.  As a result, the pyrolysis products recovered in an open medium is the sum of those from kerogen and from a part of the NSO compounds.  Under these conditions, the cracking reactions of kerogen 1 and those of compounds NSOs 1 can be combined into a single reaction.  The methodology for acquiring these parameters using the open medium is described in the paragraph "Acquisition of Parameters".  It has been applied to the four main types of organic matter contained in sedimentary rocks and classified as Type I, Type II, Type III and Type II-S.  For each of these types of organic matter, a representative sample was chosen and a kinetic scheme was developed for each: the kinetic data are summarized in Table 2.  Grade Class Gas fraction Cu.  C, 4.  mobile C, 4.  immobile Solid fraction Total EP log A chemical kerogen H20 H2S CO2 C, C2 C3-C4 sat aro sat aro nsos m am 1 aro 2 aro 3 nso im kero 2 kero 3 kero 4 prechar Type I kero 1 3.9 1.0 2 , 2 1.1 1,2 2,4 5.3 1.5 6.4 1.8 2.9 3.6 26, 8 39.9 100.0 48.0 0.9 14.75 50.0 0.8 14.75 52.0 6.0 14.75 54.0 13.0 14.75 56.0 74.2 14.75 58.0 5.1 14.75 Total ___. _. __. . _. . . . ___. _. . _. _. '- -.  . .   _- • --- • --- ~ _-.  100 0 ~ _--.  kero 2 3.6 6.4 5.4 • 29.7 M ~~ - ~~ - ~ ~~ - ~~ 96.4 100.0 58.8 100 13.76 kero 3 3 4 12.1 966_- ~ __-_ 1000 544 6 100 11 51 NSOs Im - • 100.0 48.0 0.9 14.75 100.0 50.0 0.8 14.75 52.0 6.0 14.75 54.0 13.0 14.75 56.0 74.2 14.75 58.0 5.1 14.75 100 0 48.0 6.0 13.28 50.0 20.0 13.28 52.0 63.0 13.28 54.0 11.0 13.28 100.0 ~ _ ~ _ ~ _-_ ~ 5.3 1.5 3.9 1.0 2.2 1.1 1.2 2.4 64, 2 39.9 5.5 Aro 1 lm Total w. ~ _. . . . -_ ~~.  Total 0.9 1.2 2.5 6.0 7.7 Type II kero 1 5.0 2.5 3.8 0.8 0.6 1.2 2.2 0.9 2.5 2.0 2.1 4.2 19.7 52.2 100.0 44.0 1.4 13.13 46.0 3.9 13.13 48.0 20.1 13.13 50.0 63.7 13 13 52.0 8.9 13.13 54.0 2.0 13.13 kero 2 Total. ___ r. . r. __ _____-_. _. __-. --- 2.2 0.9 2.5 6.2 21.8 ~~ --- _ ~~ - - - __, __-__. . _. .  ~ 1000 100.0 58.8 100 13.76 kero 3 3.6 96.4 100.0 546 100 1151 NSOs lm 34_TT ^ _, _ 9661000 44.0 1.4 13.13 5 , 0 2,5 3,8 1,1 0.6 1,2 --- ~ _ 52,2 46,0 3,9 13,13 48,0 20,1 13,13 50,0 63,7 13 , 13 52.0 8.9 13.13 54.0 2.0 13.13 Aro 1 lm 6.7 0.9 1.1 2.3 5.6 7.2 11.3 Total _. -. _-__. . -. .  •. _. _. . .   -. - '~ _-. _. -. ,. __'-- 100.0, 5.1 100.0 48.0 6.0 13.28 Total 59.9 50.0 20.0 13.28 52.0 63.0 13.28 54.0 11, 0 13.28 100.0 Type III kero 1 16.0 11.0 1.1 0.4 0.5 0.8 0.6 1.7 0.4 0.5 -0, 9 4.2 61, 9 100.0 44.0 0.3 13.61 46.0 5.5 13.61 48.0 14.0 13.61 50.0 27.3 13.61 52.0 36.9 13.61 54 , 0 12.0 13.61 56.0 4.0 13.13 Total-_. -.  •. -_-. ~. -. - ~ -. _. . . _--- -_-. .  ^ • _--- • - • - • -.  100 0 kero 2 2.8 97.2 100.0 62.2 100 14.47 kero 3 2 0 980_ ~.  1000 56.9 100 1074 NSOs lm 16.0 11.0 1.1 0.4 0.5 0.8 0.6 1.7 1.3 4.7 61.9 100.0 44.0 0, 3 13.61 46.0 5.5 13.61 48.0 14.0 13.61 50.0 27.3 13.61 52.0 36.9 13.61 54.0 12.0 13.61 56, 0 4.0 13.13 Total 100 0 Aro 1 lm 0.9 1.2 2.5 6.0 7.7 12.1 64.2 5.5 100.0 48.0 6.0 13.28 50 , 0 20.0 13.28 52.0 63.0 13.28 Total 54.0 100 0 13.28 Type 11-S kero 1 5.4 5.0 2.5 1.2 0.7 1.4 1.6 2.2 1.2 1.6 3.2 25.2 48.8 100.0 44.0 3.8 13.64 46.0 13.1 13.64 48.0 25.3 13, 64 50.0 29.5 13.64 52.0 17.1 13.64 54.0 8.3 13.64 56.0 2.9 13.64 _ Total -_ _v.  .  .  • ---- - •. ,.  •• - --- •. -_. . _100.0 kero 2 3.6 96.4 100.0 58.8 100 13.76 kero 3 3.4 966 1000 546 100 1151 NSOs 1m 5, 4 5.0 2.5 1.2 0.7 1, 4 1.6 2.2 1.2 4.8 25.2 48.8 100.0 44.0 3.8 13.64 46.0 13.1 13.64 48.0 25.3 13.64 50 , 0 29.5 13.64 52.0 17.1 13.64 54.0 8.3 13.64 --- •• __. _. _-__. _.  . ~~. . . . _. __-. •. . _-_.  _. -_-. -_-- • • ~ ••. -IN-261.97-MI 1 Im 6.7 0.9 1.1 2.3 5.6 7.2 11.3 10 5.1 100.0 59.9 50.0 20.0 13, 28 52.0 63.0 13.28 54.0 11.0 13.28 Total _ 100.0 Type 1 NSOs 0.8 2.5 1.3 2.6 10.0 4.3 9.0 35 0 34.5 100.0 52.0 50.0 13.50 Type II 54.0 40.0 13.50 Type III 56.0 7.0 13.50 Type II-S 58.0 3.0 13, 50 Total 100.0 2906482 17 Table 2: Kinetic pattern and parameters for the 4 major types of organic matter contained in sedimentary basins The elemental compositions of the various kerogens, NSOs and aromatic C14 + fractions are given in Table 3.  Class type C H N 0 S Total H / C OIC chemical kerogen Basic composition of organic matter (%) Keratogenic atomic ratio 1 78. 7 9. 6 7. 7 3. 30. 6,100. 0 1. 460 0. 032 kerogen 2 85. 5 4. 4 7. 1 2. 7 0. 3,100. 0 0. 611 0. 024 kerogen 3 85. 7 3. 3 7. 7 3. 0 0. 4,100. 0 0. 459 0. 026 ____________ kerogen 4 85. 9 2. 2 8. 3 3. 2 0. 4,100. 0 0.  302 0. 028 kerogen 1 76. 1 7. 7 10. 6 1. 8 3. 9,100. 0 1. 212 0. 017 kerogen 2 84. 7 4. 6 5. 8 1. 6 3. 2,100. 0 0. 658 0. 014 kerogen 3 85. 0 3. 4 6. 4 1. 7 3. 5,100. 0 0. 481 0. 015 kerogen 4 85. 2 2. 1 7. 0 1. 9 3. 9,100. 0 0. 297 0. 017 III kerogen 1 66. 0 5. 8 26. 0 1. 30. 9,100. 0 1. 047 0. 015 kerogen 2 81. 9 4. 4 12. 0 1. 1 0.  6,100. 0 0. 638 0. 010 kerogen 3 81. 8 3. 7 12. 7 1. 2 0. 6,100. 0 0. 540 0. 011 _____ kerogen 4 81. 7 3. 2 13. 2 1. 30. 6,100. 0 0. 463 0. 012 Il-S kerogen 1 69. 8 7. 3 9. 4 2. 7 10. 8,100. 0 1. 247 0. 029 kerogen 2 80. 9 4. 5 4. 8 4. 1 5. 7,100. 0 0. 666 0. 038 kerogen 3 80. 8 3. 4 5. 2 4. 5 6. 1,100. 0 0. 510 0. 041 kerogen 4 80. 6 2. 3 5. 6 4. 8 6. 6,100. 0 0. 348 0. 045 NSO im 84. 5 11. 7 2. 7 0. 9 0. 3,100. 0 1. 657 0. 008 Aro 1 im 87. 7 11. 2 1. 1,100. 0 1. 530 Aro 2 1m 92. 5 7. 5,100. 0 0. 979 __Aro 3 im 93. 0 7. 0 100. 0 0. 898 NSO im 79. 1 8. 4 4. 8 1. 4 6. 2,100. 0 1. 276 0. 013 Aro 1 im 84. 6 8. 9 6. 5,100. 0 1. 268 Aro 2 im 85. 1 6. 9 8. 0 100. 0 0. 979 Aro 3 im 85. 4 6. 4 8. 3,100. 0 0. 897 III NSO im 80. 6 7. 3 10. 0 0. 3 1. 9,100. 0 1. 086 0. 003 Aro 1 im 90. 0 10. 0 1. 333 Aro 2 im 92. 5 7. 5 0. 979 Aro 3 im 93. 0 7. 0 0. 898 11-S NSO im 78. 1 8. 3 4. 3 1. 6 7. 7,100. 0 1. 282 0. 016 Aro 1 im 84. 6 8. 9 6. 5 1. 268 Aro 2 im 85. 1 6. 9 8. 0 0. 979 Aro 3 im 85. 4 6. 4 8. 30. 897 Table 3: Elementary composition of different kerogens and associated products.  From the proposed kinetic schemes, it is possible to calculate a transformation rate identical to that defined by the Rock Eval technique (EP-0767375).  From these calculations, charts for each type of kerogen can be proposed to determine the values of this rate of transformation on natural samples of varied thermal maturity.  To do this, the following steps are carried out.  The transformation rate of the kerogen is determined on an immature sample by pyrolysis of Rock Eval type.  The latter makes it possible to measure the rate of production of the hydrocarbons during thermal cracking of the kerogen.  When the measurement of the peak of hydrocarbon production is made on an immature sample, its time integral represents the maximum value of the petroleum potential of the sample, denoted S20, since the sample has not yet undergone any thermal maturation.  The conversion rate (TR) of kerogen is therefore defined as follows: TR Kinetic = hydrocarbons generated / S2o 5 In sedimentary basins, it is necessary to determine the transformation rate of kerogens in order either to calibrate the thermal history or to predict whether petroleum fluids have actually been generated.  For this it has been proposed by Espitalié et al.  (1977), to use the following equation: TR Naturel = (S2o ù S2) / S2o 10 or, if one takes into account the carbon contents of the samples: TR = ((S2 / Co) ù (S2 / C)) / (S2o / Co)) With: S2: residual petroleum potential of a sample (in mg per g of rock) S2o: initial petroleum potential of an immature sample (in mg per g of immature rock) C organic carbon content of a sample (in g of C per g of rock) Co content of organic carbon of an immature sample (in g of C per g of immature rock) When the samples have already undergone thermal maturation, kerogen 2 is produced as indicated in the kinetic scheme (FIG. 3).  Consequently, the measured S2 comes from the residual S2 in the initial kerogen and from the S2 generated from the kerogen 2.  Also, thanks to the kinetic scheme proposed, it is possible to quantify, for any rate of transformation of the initial kerogen, the respective quantities of residual initial kerogen and that of generated kerogen 2.  Knowing the amount of residual initial kerogen, it is possible to predict the value of the peak S2, namely: S2 sample = S20% of residual initial kerogen From this equation, the natural TR can thus be determined, and it is then possible to draw up TR Kinetic and Natural TR charts for any immature sample.  By measuring the TR Natural, we deduce the kinetic TR.  By way of example, such charts are plotted in FIGS. 4A to 4C for the four initial kerogens studied, kerogens of type I, II, III and II, respectively.  NTR represents the natural TR and KTR represents the kinetic TR.  The cracking scheme of a kerogen according to the invention may, for example, be used in the context of a basin simulation.  It is indeed recognized that the process of oil and gas formation in sedimentary basins is the result of a thermal cracking of the organic matter (kerogen) present in the parent rocks.  To be perfectly predictive of the amount of hydrocarbons present in a reservoir rock following cracking started in a source rock, it may be advantageous to associate with this scheme a kinetic scheme of the cracking of the oils.  Cracking of Oils Kinetic schemes developed from laboratory experiments under high temperature conditions (usually above 250 C in practice) can be used to determine kinetic parameters.  The latter are used to determine the thermal reactivities under natural conditions, that is to say below 250 C.  Thus it is possible, according to the thermal reactivity found for the different chemical classes, to make groupings between certain classes and thus to reduce the complexity of the initial kinetic schemes.  This grouping technique is classically called lumping.  This grouping makes it possible to regenerate a simpler kinetic model that can be used in models of sedimentary petroleum systems.  The number of chemical classes of the thermal cracking model is indeed a highly limiting parameter for the calculation times of pond simulators.  There are two requirements, however, for lumping: limiting precision losses on the prediction of overall hydrocarbon cracking rates (the pooled model must be equivalent to the full model for predicting hydrocarbon cracking windows); to obtain, after grouping, chemical classes having a business interest: integrity of the calculation of the thermodynamic properties of the total hydrocarbon fluid, integrity of the concepts of petroleum (liquid hydrocarbons) and gas (gaseous hydrocarbons).  This double constraint implies the preservation of certain classes and reactions, including the cracking of heavy products.  The other classes can be grouped either by bubble points (grouping

  preserving the calculation of the thermodynamic properties), or by chemical structure and thermal reactivity (grouping preserving the calculation of the cracking windows). This kinetic cracking model comprises 16 classes whose elemental composition is given in Table 4: Fluid with sulfur Fluid without sulfur Class CHS Total CH Total H2S 5.88 94.12 100.00 C1 75.00 25, 00 100.00 C2 80.00 20.00 100.00 C3 81.82 18.18 100.00 C4 82.76 17.24 100.00 C6-C14 sat 84.40 15.60 100.00 BTXN 91, 03 8.97 100.00 C14_ alkyl 89.45 10.55 100.00 C14_ methyl 90.43 9.57 100.00 C14 + Sat 85.07 14.93 100.00 C14 + Ara-1 84.37 9.94 5.69 100.00 89.46 10.54 100.00 C14 + Aro-2 85.06 6.94 8.00 100.00 92.46 7.54 100.00 C14 + Aro-3 85.37 6.38 8.25 100.00 93.04 6.96 100.00 NSOs 84.00 9, 50 6.50 100.00 89.84 10.16 100.00 prechar 86.15 4.98 8.87 100.00 94.54 5.46 100.00 tank 86.74 3.93 9.33 100.00 95.67 4.33 100.00 Table 4: list and elemental composition of the classes included in the kinetic model 5 The kinetic scheme is given in Table 5: the reactions can be represented by activation energy distributions with a single frequency factor be either mono energetic. The stable classes are H2S, C1, C2, C3, C4, BTXN and char, Class Fraction gas Fraction C14. Fraction C14 + Solid fraction EP log A chemical H2S C, C2 C3 C4 Sat BTXN alkyl methy Sat Am-1 Aro-2 Aro-3 prechar char Total C1 + alkylaro 10.5 4.7 1.7 1.6 10.0 25 , 7 45.8 100 _0 56.0 100.0 13.1 C14 methyl aro 10 _9 50 _6 38 _5 100 _0 55.0 100.0 11.7 14. Sat 4.0 20.0 23.0 24, 0 - 22.0 7.0 100.0 70.5 73.0 17.8 76.0 27.0 17.8 C14. Sat 4.0 7.0 9.0 6.0 50.0 4.0 6.0 11.0 100.0 67.5 60.0 17.8 70.5 40.0 17.8 C14, Atlantic 1 1.8 2.5 1.6 1.7 1.9 7.0 1.6 0.4 18.0 48.0 15.5 100.0 80.0 13.3 5452.0, ___, 0 20.0 13.3 14, Aro-2 3.0 70.0 27.0 100.0 10.8 49.0 100.0 10.8 C 14, Al-3 7.1 92, 9 100.0 54.3 100.0 12.0 NSOs 0.8 2.5 1.3 1.3 1.3 10.0 3.5 0.8 9.0 35.0 34.5 100.0 52.0 40 , 0 13.1 56.0 55.0 13.1 58 58.0 5.0 13 1 -------- --- __ prechar 5.0 95, 0 100.0 56.0 100, Table 5: Kinetic diagram of thermal cracking of petroleum fluid The scheme was tested on laboratory experiments carried out on a natural petroleum fluid. From this kinetic scheme, a second scheme has been proposed which groups together certain chemical families. The grouping of constituents and reactions in order to reduce the size of a reaction scheme is a common practice in reaction chemistry, more particularly in radical kinetics. Various mathematical techniques have been developed for this purpose, depending on the degree of reduction and the nature of the desired clustering (generic pool, reaction, etc.). In general, the purpose of grouping is to simplify the implementation of the kinetic model. Thus, usually the kinetic schemes are calibrated and grouped for thermal conditions and durations corresponding to the field of application. In the specific case of the prediction of oil reactivity, it is not possible to calibrate and group the model at the temperatures and durations observed in nature. An originality of the method proposed here for cracking oils thus consists in calibrating a complex reaction scheme under laboratory conditions (high temperature, short duration); - to then realize a reduction of the diagram for a restricted domain of application, different from the conditions of rigging: low temperature (geothermal gradient), long duration (several million years). This strategy is carried out by means of a numerical simulator of reaction schemes, calculating the rates of cracking reactions at both high and low temperature. The analysis of simulated data at low temperature, for each class of the complex scheme, makes it possible to select the classes to be grouped (according to their reactivities, and / or their molecular weight). Then, the low temperature pooled compositions allow to rewrite a simplified kinetic scheme extracted from the reactions of the original kinetic complex model. The overall strategy is summarized in Figure 1, in which: CD AD ED SC S SD L RS Experimental Domain Application Area Experimental Data Complex Kinetic Scheme (Experimental Domain) Simulation under Application Domain Conditions Simulated Data Under the conditions of application Grouping ("Lumping") Reduced kinetic scheme (field of application) According to this approach, three examples of lumping according to the invention are described below: reduction 1, 2 and 3. The new chemical classes thus obtained and the new cracking parameters are summarized in Tables 6 and 7. The reduction 3 proposes a scheme with 8 classes, but we would not go beyond the scope of the invention by realizing a grouping of classes of to obtain a lower class number. Initial model type reduction 1 reduction 2 reduction 3 Class list H2S H2S H2S chemical H2S C1 C1 C1-C4 C2 C2 C2-C4 014_ C3 C3-C4 C14_ C14 + Sat C4 C14_ C14 + Sat C14 + Aro C14_ Sat C14 + Sat C14 + Aro NSOs BTXN C14 + Aro NSOs prechar C14_ alkyl aro NSOs prechar char C14_methyl aro prechar char C14 + Sat char C14 .. Ara-1 C14 + Aro-2 C14 + Aro-3 NSOs prechar char Number of classes 16 10 9 8 Table 6: possibilities of reduced diagrams for cracking of petroleum fluids. This reduced scheme is given in Table 7 and the corresponding elementary compositions in Table 8. 2906482 23 Gas class C14-C14 + Solid EP log A chemical H2S C1 C2 C3-C4 total Sat Aro NSOs prechar char Total C14_ 6.0 20.0 48.0 26.0 100.0 70.2 32.0 17.8 6.0 20.0 48.0 26.0 100.0 72.6 34.0 17.8 12.0 5.0 4.5 78.6 100.0 56.6 14.0 13.1 18. 4 81.6 100.0 53.6 10.0 10.8 100.0 100.0 75.0 10.0 10.8 C14 + Sat 4.0 7.0 18. 0 64.0 7.0 100.0 67.5 60.0 17.8 3.0 7.0 18.0 66.0 6.0 100.0 70.4 40.0 17.8 C14 + Aro 5.0 5.8 4.0 9.0 21.5 44.5 10.2 100.0 52.1 40.0 13.3 5.5 94.5 100.0 48.5 20.0 10.8 6.0 94.0 100.0 51.0 20.0 10.8 7.1- 92.9 100.0 55.8 20.0 12.4 NSOs 2.7 1.4 2.6 14.3 9.0 35.0 35.0 100.0 52.0 40.0 13.1 56.0 55.0 13.1 0 5.0 1 3.1 58.0 ---- - --- - --- - - 95.0 -------- 56.0 100.0 12.4 Prechar ---- 5.0 100.0 Table 7: kinetic parameters for reduced schemes. Petroleum sulphide fluids Petroleum sulphide fluids Chemical class CHS Total CH Total C14- 85.26 14.74 0.00 100.00 C14 + Sat 85.07 14.93 0.00 100.00 C14 + Aro 84.85 8.03 7.13 100.00 91.36 8.64 100.00 NSOs 84.00 9.50 6.50 100.00 89.84 10.16 100.00 prechar 86.15 4.98 8.87 100.00 94.54 5.46 100.00 tank 86.74 3.93 9.33 100.00 95.67 4.33 100.00 5 Table 8: Elemental Composition of Chemical Classes for Reduced Schemes. Parameter acquisition method Acquisition of kinetic parameters The kinetic schemes defined for studying and modeling the thermal cracking of petroleum fluids must be supplemented by the definition of their kinetic parameters and their stoichiometric coefficients. To date, the kinetic models used in digital simulators of sedimentary basins to represent the formation of oil in source rocks more or less correspond directly to a set of parallel, independent and first order thermal cracking reactions. Kinetic parameters (activation energies, pre-exponential factors) and the stoichiometric coefficients associated with these reactions are calibrated using laboratory pyrolysis experiments on organic matter (kerogen) extracted from immature source rocks (Ungerer et al. Pelet, 1987). Pyrolysis experiments are intended to measure, under laboratory conditions, the formation rate of petroleum fluids as a function of temperature and time. Two types of experimental techniques can be used for this purpose: open-system pyrolysis and closed-system pyrolysis (with or without the addition of water). In the first case, the mobile effluents from the pyrolysis of kerogen are removed from the reaction medium as they are produced (either by means of a circulating gas or by vacuum suction). In the second case, the pyrolysis effluents accumulate in the reaction medium and may therefore undergo secondary cracking. In general, the kinetic models for the thermal cracking of kerogen represent petroleum fluids (oil and gas) in a very simplistic way, in the form of a single constituent. In this case, non-compositional experimental techniques, which are quick to implement and allow only a partial mass balance (on the hydrocarbon products), are used to calibrate the kinetic parameters. Rock Eval and Pyromat open-system pyrolysers allow the acquisition of calibration data from non-compositional kerogen cracking models. Towards the end of the 1980s, so-called kinetic compositional models appeared, in which the oil and gas formed in the parent rocks are represented by several constituents (classes of bubble points, structural classes, etc.). To calibrate the speed parameters of these models, either open pyrolysis experiments or closed system pyrolyses are used. Whether compositional or not, the acquisition of pyrolysis data in the laboratory has at least the following two limitations. On the one hand, the compositional data obtained in an open system only allow a partial mass balance of kerogen cracking, based on the volatile hydrocarbon constituents only. For this reason, these data are applicable only to kinetic schemes whose reactions limit it to describe the conversion of kerogen to hydrocarbons, without taking into account the non-hydrocarbon components or the fate of the residual carbon solid mass. On the contrary, experiments carried out in a closed system allow, in principle, a complete mass balance of the thermal conversion of kerogen. Nevertheless, these experiments are expensive in terms of material, time and require a relatively large mass of kerogen. Consequently, these techniques are difficult to implement on a case-by-case basis, and the number of data produced from a kerogen sample generally makes it possible to develop only simple kinetic models, with a limited number of reactions. and, therefore, parameters to be calibrated. Thus, according to the invention, these parameters are calibrated by means of pyrolysis experiments coupled with digital inversion techniques. The experimental methodology according to the invention is a compromise between the open system approach and the closed system approach. Indeed, it makes it possible to fully calibrate the petroleum product cracking model, obtaining an equivalent result depending on whether the experimental data are obtained in an open system or in a closed system, or both at once. In addition, based on a double mass balance and carbon, it allows to calibrate both the formation of hydrocarbon effluents, non-hydrocarbons, and the evolution of the solid fraction consisting of a mixture of immature kerogen, mature kerogen and residue carbon. Advantageously, the constraints associated with the following kinetic parameters are defined: the cracking reactions are assumed to be parallel, independent, of order 1 kinetics obeying the Arrhenius law: K = Ae R; T, where A is the kinetic constant (frequency factor), E the activation energy, T the temperature and R the ideal gas constant; All the reactions have the same frequency factor; the possible range of activation energies is chosen between 40 and 80 kcal / mole spaced 2 kcal / mole between 2 reactions. The method comprises the following steps: 1. pyrolysis experiments are carried out in an open environment and / or in a closed environment; 2. the parameters are determined by digital inversion. Determination of Kerogen Cracking Scheme Parameters and Coefficients - Determination of E and A Parameters Open pyrolysis is carried out at different heating rates of the original kerogen and only the S2 peak production rate is measured. defined as the sum of all pyrolysis effluents with the exception of non-hydrocarbon gases (CO, CO2, H2, N2, H2S), water (H2O). By inversion we obtain the E and A by making the assumptions previously indicated. Cracking rates are obtained from open pyrolysis experiments carried out with a device called Rock Eval 6, described for example in EP-0-767-375. The kerogen charges used for each experiment are adjusted to obtain identical heights of the peak S2 between the different tests in order to ensure better reproducibility of the measurements and thus to obtain more precise experimental results. The overall production rates of the pyrolysis effluents are measured at different heating rates: 2, 5, 10, 15 and 25 C / min from an isotherm at 200 ° C for 15 minutes and then a temperature rise to 700 C. Pyrolysis is carried out under a nitrogen flow of 100 ml / min. From the hypotheses previously described (cracking reactions assumed to be parallel, independent and of order 1,.), Each kinetic model can be calibrated by the adjustment of 23

  parameters: - a frequency factor, - the 21 activation energy distribution coefficients, - the petroleum potential of kerogen (S2p) [corresponding to the total amount of pyrolysis products generated by heating the sample to a temperature and a 25 infinite time]. The global kinetic parameters to describe the genesis speed of all the products contained in the peak S2 are adjusted by numerical inversion of the experimental data obtained with the Rock Eval 6. The numerical inversion consists in the determination of a set of values which locally minimize a quadratic error function (sum of the square of the residuals between the hydrocarbon formation rates measured by the Rock Eval and those calculated by the kinetic model). Any constrained optimization algorithm (to ensure conservation of mass) adapted to continuous quadratic functions can be used: Levenberg-Marquardt method, 5 conjugate gradients, quasi-Newton, etc. Determination of Stoichiometric Coefficients A new pyrolysis is carried out for 100% conversion of the initial kerogen, and the pyrolysis effluents are recovered with an S2 analyte to separate them into different chemical classes. The S2 analyzer is an apparatus derived from the Rock Eval 6 apparatus, also described in EP-0-767-375, which is equipped with a trap for recovering the liquid fraction of the previously defined peak S2. This gives us the stoichiometric coefficients for 100% conversion of kerogen. The resulting stoichiometric reaction is as follows: Kerogen = CO + CO2 + H2S + H2O + C1 + C2 + C3 + C4 + C6-C14 saturated + C6-C14 aromatic + C14 + saturated + C14 + aromatic + NSOs pentane + NSOs DCM + kerogen 2 The stoichiometric coefficients are measured in several steps: 1) a first pyrolysis at 25 C / min between 200 C and 650 C in order to draw up the following balance sheet: Mass of initial kerogen = x1 (CO) + x2 (CO2) + x3 (S2) + x4 (kerogen 2) 2906482 28 The CO, CO2 and S2 peak gases are directly quantified by the Rock Eval 6 apparatus. The amount of kerogen 2 is determined from the carbon footprint after determining the carbon content in the initial kerogen and knowing the peak S2 carbon content estimated at 83%. 2) a second pyrolysis at 25 Clmin between 200 ° C. and 650 ° C. in order to draw up the following balance sheet: Fraction C6 + of the peak S2 = C6-C14 saturated + C6-C14 aromatic + C14 + saturated + C, 4 + aromatic + NSOs pentane + NSOs DCM 10 This pyrolysis is performed with the S2 analyzer. 3) some closed pyrolysis points (annexed step) H2S from cracking of kerogen alone can not be determined during open pyrolysis due to the possible contribution of H2S from thermal decomposition pyrite often associated with kerogen. This pyrite indeed decomposes beyond 500 C under the conditions of pyrolysis carried out with a device of Rock Eval type. Also to measure this compound, pyrolyses in a closed environment are realized because it is possible to lower the temperature and increase the residence time. The conditions are chosen so as to obtain a degree of conversion, as determined in an open environment, of kerogen close to at least 90%. The H2S thus generated under these conditions is quantified as previously indicated. If in these experiments, mass balances are made, it is possible to calculate the amount of water for a conversion rate close to 100%. Otherwise it is possible to quantify the water yield by a pyrolysis experiment conducted between 200 and 650 C at 25 C / min with determination of water by a specific detector. 4) specific pyrolysis in an open medium for the compounds C 1, C 2, C 3 and C 4. These pyrolyses are carried out under vacuum at 25 C / min between 200 and 650 C with continuous drawing by a Toepler pump. The latter also makes it possible to recover quantitatively all the gases produced for molecular analysis by gas chromatography. However, the methane can also be assayed by coupling the Rock Eval 6 to a specific detector of infra-red type, for example. Finally, these hydrocarbon gases can also be quantified by a coupling between the Rock Eval 6 and a gas chromatograph. 5 - Verification of the balances It is verified that the sum of the hydrocarbon gases measured, added to the total quantity of the liquid fraction C6 + of the peak S2 is well coherent with the value of the peak S2 directly measured by the Rock Eval 6.

Determination of the parameters and coefficients of the oil cracking scheme For these parameters, it is necessary to carry out pyrolyses in a closed medium. The acquisition of kinetic parameters in a closed environment requires having a set of experiments sufficient to monitor the production and disappearance of the main chemical classes at different temperatures and to ensure the quality of the mass balances. For example, 25 experiments covering 3 temperatures are generally sufficient and the recovery rate of all pyrolysis effluents must be greater than or equal to 95%. This method was used for the acquisition of kinetic parameters for kerogens 2 and kerogens 3 and for all the kinetic parameters of unstable liquid compounds in the temperature range selected for the experiments. - Determination of E and A parameters and stoichiometric coefficients Stoichiometric velocities and coefficients are determined numerically from the mass balances obtained in all the experiments. By following the evolution of each class in terms of production and disappearance, it is possible to write a prior kinetic scheme which will serve as an initial step in the calculation of the kinetic parameters. The calibration of the kinetic and stoichiometric parameters is carried out as follows. A numerical simulator is used to solve the speed laws of the chemical reactions of the kinetic pattern as a function of time and temperature. Simulations 2906482 are made under experimental time and temperature conditions. The calculated data for all the chemical classes are compared with the corresponding measured data and the differences between the measured quantities and the predicted (residual) quantities are minimized by numerical inversion of a squared error function (defined as the sum of the square residuals). Any constrained optimization algorithm (to ensure conservation of the mass) adapted to continuous quadratic functions can be used: Levenberg-Marquardt method, conjugate gradients, quasi-Newton, etc. -Verification of the balance sheets 10 Knowing the elementary compositions of the starting petroleum products and of all the liquid and gaseous effluents, the mass of residual solid at 100% conversion and its elemental composition in C, H, O and S are determined. In sum, the method according to the invention for determining kinetic parameters and stoichiometric coefficients associated with kinetic schemes for thermal cracking of petroleum products makes it possible to determine such parameters that are coherent both with system pyrolysis experiments. open and closed system. Moreover, based on a dual mass and carbon balance, it makes it possible to calibrate both the formation of hydrocarbon and non-hydrocarbon effluents and the evolution of the solid fraction constituted by a mixture of immature kerogen, mature kerogen and carbon residue. A detailed example of an experimental protocol using the methodology is described below. For example, reference may be made to the following document: Behar, F., Leblond, C., St. Paul, C., 1989. Quantitative Analysis of Pyrolysis Effluents in Open and Closed Environments. Oil and gas science and technology 44, 387-411.

Example of an experimental protocol A - PYROLYSIS SYSTEMS A 1 1 Closed Pyrolysis The samples are heated in a medium kept closed for the duration of the pyrolysis. The pyrolysis chamber is previously purged to remove all the oxygen from the air. A first set of experiments is carried out in order to define the most appropriate temperature and time range to follow the conversion of the selected loads.

The experiments are carried out in closed reactors under an inert gas (for example: helium, nitrogen), with or without the addition of water. Two types of reactors are used: - isobaric reactors of low capacity (less than 5 ml): gold tubes of various sizes and welded at both ends are used in particular. Back pressure is imposed throughout the duration of the experiments in order to avoid the explosion of the tubes due to the internal pressure generated. The charge is generally between 30 mg and 1 gram. - Isochoric reactors of medium or large size (more than 5 ml): used for loads greater than one gram, these reactors consist of a hermetically sealed stainless steel capacity. Such pyrolysis systems are commercially available (Parr reactors).

Gold tubes (isobaric reactors) are used to minimize interactions between the reactors and the reaction chemical medium. Two tubes are heated at the same time: one will be devoted to the analysis of the gaseous compounds and the other to the balance of the liquid and solid compounds. The mass of the initial charge is determined by weighing between the empty tube and the solid tube before welding.

The gold tubes are placed in an autoclave which contains a second gold tube in which a thermocouple is placed in order to have the temperature closest to that which the charge to be pyrolyzed. The autoclaves are then placed in a chamber previously heated to the desired temperature. The pyrolysis times are chosen to minimize the influence of the rise in temperature. At the end of the pyrolysis, the autoclave containing the gold tube (s) is immediately immersed in water at room temperature in order to stop the cracking reactions as quickly as possible. In the case of isochoric reactors, an inert gas pressure is introduced at ambient temperature. The reactors are then placed in a chamber previously heated to the chosen temperature. At the end of the pyrolysis, they are cooled to ambient air. The pyrolysis conditions are isothermal conditions with varying residence times. The heating conditions for kerogens depend on their chemical structure and degree of maturity. For low-maturity kerogens, the temperature range is generally between 150 C and 375 C for durations of between 1 hour and 10 months. For more mature kerogens, the temperatures are between 350 and 550 C for equivalent residence times. For all the experiments carried out on liquid products, the conditions are isothermal between 200 and 500 C: the choice is there also a function of the thermal reactivity of the studied products. Open Pyrolysis The samples are heated in a pyrolysis chamber flushed with a gas stream such as, for example, Rock Eval pyrolysis. This pyrolysis makes it possible to determine the non-hydrocarbon gases CO and CO2 as well as all the gaseous or liquid products detected by a flame ionization detector or S2 peak (Patent No. EP-0-767-375 for the Rock Eval 6) . The tests are carried out in temperature programming between 2 and 25 C / minute under a nitrogen flow of 100 ml / minute. A second pyrolysis system is used to determine the composition of the liquid fraction of the S2 peak. This system is called S2 analyze. The liquid effluents are recovered in a trap cooled with liquid nitrogen. The hydrocarbon gas fraction of the S2 peak may be assayed either by Rock Eval coupling or by micro-gas chromatography or by other techniques such as coupling between thermogravimetric analysis and infrared detection (TG / FTIR) or vacuum pyrolyses in a medium. opened with quantitative recovery of the gases and then analyzed by gas chromatography.

15 2906482 33 B - ANALYTICAL PROTOCOLS B -1 Recovery and quantification of gases B - Quantification of gases in an open environment 5 Rock pyrolysis Eval is used to determine the non-hydrocarbon gases CO and CO2. The hydrocarbon gas fraction of the S2 peak may be assayed either by Rock Eval coupling or by micro-gas chromatography or by other techniques such as coupling between thermogravimetric analysis and infrared detection (TG / FTIR) or vacuum pyrolysis.

10 B û 1û b Closed gas quantization For gold tube pyrolyses, the gold tube is drilled in a vacuum line equipped with a Toepler pump. The latter makes it possible to store the generated gases in pre-calibrated volumes, the total quantity of which can therefore be estimated. These gases are then completely transferred to an ampoule and quantitatively assayed by gas chromatography. Thus, the quantities recovered are expressed in absolute yield (%, mg / g or mg / gC) relative to the feed introduced for H2, CO, CO2, H2S, C1, C2, C3, n-C4 and i-C4. This quantitative determination makes it possible to calculate the balance C, H, O and S for the gaseous fraction. Depending on the type of closed reactor, the gas recovery mode may be different. In the case of isochoric reactors (Parr type), a gas collection system by expansion in a previously evacuated container makes it possible to recover the gaseous fraction which is then analyzed by the same apparatus as that used for the gases recovered in the tubes. Golden.

2906482 B - 2 Determination of the light C6-C14 B fraction 2 - 2 Open pyrolysis Using the S2 analyzer, the liquid effluents are trapped in liquid nitrogen.

Once the liquid nitrogen has been removed, the trap is rinsed with n-pentane. All of the pentane stock solution is fractionated by liquid chromatography on a small column (Pasteur pipette size) filled with Florisil to retain the high molecular weight compounds. The eluate is then deposited on a second column filled with silica in order to separate 2 fractions: after a first elution with n-pentane, the solution contains all of the saturated hydrocarbons. The second elution using a npentane / dichloromethane mixture (85/15, v / v) makes it possible to recover the aromatic C6-C14 fraction. After addition of an internal standard in each of the two solutions, the two solutions are injected into a gas chromatograph equipped with a capillary column. The total surface area (peaks + unresolved background) is integrated from the hydrocarbon stream. C6 to the C14 hydrocarbon. This surface expressed in pvolts is then converted into a mass knowing the concentration and the detected surface of the internal standard. It should be noted that in this protocol hydrocarbons containing 5 carbon atoms are not metered. The quantities are then reduced to the initial charge just like the gas dosage.

With regard to the elemental compositions, respective average values of 15.6% in H and 84.4% in C are attributed for the saturated fraction. For the aromatic fraction, average values of 9.0% in H and 91.0% in C. B 2 -2 b Closed pyrolysis 25 The second gold tube is pierced in a piercer equipped with a needle and filled with n-pentane . The contents of the piercer are then transferred to a balloon. The gold tube is open at both ends and also placed in the balloon. The whole is then extracted for one hour under reflux and with stirring. After one hour, all of the solution which contains the soluble and insoluble products in pentane is filtered under vacuum. A first aliquot of the stock solution is taken for fractionation by liquid chromatography followed by quantitative assay using the same protocol as for effluents recovered in an open medium. B-3 Dose of the C14 + 5 B3 fraction at Open Pyrolysis A second pyrolysis is carried out with the S2 analyzer. The stock solution of pentane is evaporated under an inert gas stream. The total soluble extract in pentane is then weighed after transfer into a previously tared container. The contents are then fractionated by liquid chromatography, for example an automatic or manual system in order to recover 3 solutions: the first contains the saturated hydrocarbons, the second the aromatic hydrocarbons and the third the organic compounds which may contain sulfur, nitrogen and / or oxygen. This third fraction is called for example NSOs pentane. After removal of the solvent for the three solutions, the 3 chemical fractions are quantitatively evaluated by weighing and their amount expressed relative to the initial charge. The fraction containing the saturated hydrocarbons is injected into a chromatograph in order to determine the residual C14 2 fraction. It can also be subjected to a quantitative mass spectrometric analysis in order to measure the amount of mono aromatic structures that are present and to correct the actual amount of saturated hydrocarbons.

Once weighed, the 2 fractions respectively containing the aromatics and the hetero atomic compounds are subjected to an elemental analysis to assay C, H and S in the aromatic fraction and C, H, O, N and S in the hetero moiety. atomic. This excerpt is called, for example, NSOs DCM. For the fraction of saturated hydrocarbons an average composition of 14.9% in H and 85.1% in C is taken.

The trap is then rinsed with dichloromethane. The extract thus recovered is quantified by following the same protocol as that of the pentane extract, namely weighing after evaporation of the solvent. This fraction is subjected to elemental analysis for the determination of its elements C, H, O, N and S.

Closed Pyrolysis A second aliquot of the stock solution of pentane is taken and undergoes the same analytical protocol as for the effluents in an open medium.

The pentane-insoluble residue is dried to be ground to obtain a fine, homogeneous powder and to carry out a second extraction with dichloromethane. The stock solution of dichloromethane is totally evaporated and weighed. It contains almost all hetero atomic structures including the family of asphaltenes. This fraction is subjected to elemental analysis for the determination of its elements C, H, O, N and SB ù 4 Determination of solid residues B ù 4 to pyrolysis in open medium The solid residue is estimated from pyrolysis Rock Eval . Indeed, knowing the carbon content contained in the peak S2, and that of the initial charge, the mass of solid residue obtained during these pyrolyses is obtained from the carbon balance: Cinitial = x1 (CCO) + X2 ( CCO2) + X3 (CS2) + X4 (Cresidu) B4-4 b Closed Pyrolysis The dichoromethane-insoluble residue is recovered on the filter with the gold tube cut into pieces. Knowing the weight of the empty tube, it is possible to have a first estimate of this residue. Nevertheless, this data is rather imprecise, the residue rate is estimated as that obtained in open environment from the carbon balance. Also, the solid residues are subjected to an assay of its constituent elements C, H, N, O, S. In the particular case where the pyrolyzer charges contain pyrite, iron 25 assays are carried out.

36 2906482 B - 5 Establishment of mass balances: The same mass balances are carried out in an open and closed environment, namely: load = H2 + CO + CO2 + H2S + H2O + C1 + C2 + C3 + C4 + saturated C6-Ci4 + C6 -C14 aromatic + C14 + saturated + C14 + aromatic + NSOs pentane + NSOs DCM + residue. The carbon and sulfur content being known for each of the chemical families, it is possible to establish the two respective balances.

From the oxygen balance obtained and by difference with the oxygen content of the feed, it is possible to estimate the amount of water. Finally, once the amount of water is known, it is possible to draw up a hydrogen balance. Thus, by using the same methods of quantification and fractionation of open and closed pyrolysis products, it is possible to make a direct comparison of the results in order to highlight differences and similarities between the two methods. Other Chemical Classes The aromatic C6-C14 moiety can be separated by subfamily liquid chromatography. Each of the subfamilies is then subjected to gas chromatography analysis coupled to a mass spectrometer for molecular identification. This analysis makes it possible to subdivide the global family into five sub-families: the BTXN fraction which comprises the mixture benzene, toluene, xylene and naphthalene.

The aromatic sulfur-containing C6-C14 family which comprises aromatic sulfur compounds in the C6-C14 carbon range.

The aromatic methyl group contains the aromatic structures, that which contains the alkylated structures and finally that which contains the aromatic naphtho structures. For the aromatic C14 + chemical class, 3 subfamilies are distinguished: the aromatic C14 + 5 which are the most thermally unstable. They break down by producing new aromatic structures; aromatic C14 + 2 which themselves evolve under the effect of temperature by producing aromatic C14 + 3. Thus the use of this new kinetic scheme allows, for the first time to report not only the nature of liquid products, gaseous and solid generated during the cracking of kerogen under laboratory conditions and in geological conditions but also the composition of the fluids effectively expelled from the source rocks ... FT: METHOD OF MODELING THE THERMAL CRACKING OF KEROGENE AND PRODUCTS PETROLIERS ASSOCIATES

Claims (6)

claims   1) method for modeling the thermal cracking of at least one type of kerogen, characterized in that the following steps are carried out: reaction schemes of the thermal cracking of at least one type of kerogen, a- by individualizing at least the following chemical classes: H2O, H2S, 002 kerogen 1, 2, 3 and 4 Cl, C2, C3, C4 C14_salt, C14_alkyl, C14_methyl C14 + Aro-1, 2, 3 prechar C14 + sat NSOs kchar b- by defining a reaction scheme for the primary cracking of said kerogen type, in which it is required that each reagent be decomposed into mobile products (m) and immobile products (im) according to the following table: reagents ~ mobile products + kerogenic immobile products H2O, H2S, CO2 C14 + Arol- im C1, C2, C3, C4 + NSOs im C14_ sat, C14_alkyl, C14_methylkerogen 2 C14 + sat, C14 + Ara-1m, NSOs m kerogen   2 -> C1 + kerogen 3 kerogen 3 - C1 kerogen 4 c- by defining a reaction scheme for the secondary cracking of immobile NSOs, immobile C14 + Aro-1, immobile C14 + Aro-2, immobile C14 + Aro-3 and prechar, in which it is required that each reagent is decomposed into mobile products and still products according to the following table: 2906482 40 reagents>> mobile products + immobile products NSOs im ù> H2O, H2S, CO2 + prechar Cl, C2, C3 C14-C14-C14-alkyl, C14-C14 + alkyl, C14 + C14 + alkyl, C14 + C14 + Ara-1 im-> H2S + C14 + Aro-2 im Cl, C2, C3, C4-C14-sat, C14-alkyl, C14- methyl C14 + sat, C14 + Aro-2m C14 + Aro-2 im - ~ 1C + prechar C14 + Aro-3 im C14 + Aro-3 im ù> C1 + prechar prechar ù> C + char II- a kinetic scheme is constructed by determining parameters kinetics and stoichiometric coefficients associated with said reaction schemes, by carrying out the following 5 steps: d- Pyrolys experiments are carried out e to determine proportions of pyrolysis products for each of the following families of compounds: non-hydrocarbon gases: CO2, H2S, H2O hydrocarbon gases comprising 1 to 4 carbon atoms 10 liquid hydrocarbon compounds NSOs1 and NSOs2 solid residues: kerogen 1, kerogen 2, kerogen 3, kerogen 4, preloads pyrolysis product proportions for each of said families of compounds are determined by means of a simulation based on said reaction schemes according to claim 1; and said kinetic parameters and said stoichiometric coefficients are determined by means of a numerical inversion in which the difference between said proportions of pyrolysis products simulated in step e) and said proportions of pyrolysis products is minimized. from pyrolysis in step d). III- the thermal cracking of said type of kerogen is modeled using said kinetic scheme. 2) A method according to claim 1, wherein a numerical simulator is used to solve speed laws of said reactions of said kinetic pattern as a function of time and temperature.   3) Method according to one of the preceding claims, wherein said cracking reactions are characterized by activation energy distributions, EE1 and EE2, and activation energies, E3 and E4, as well as by stoichiometric coefficients, X1 to X7, Y1 to Y4, Z1, Z2, W1 and W2 according to the following kinetic reaction scheme: EE1 Kérogène 1 X, non HC gas + X2 HC + X3 C14 + Aro im + X4 C14 + Aro m + X5 NSOs im + X6 NSOs m + X, kerogen 2 EE1 X1 no HC gas + X2 HC + (X3 + X4) C14. Aro m + (X5 + X6) NSOs m + X, prechar EE2 Y1 no HC gas + Y2 HC + Y3 C14. Aro m + Y4 prechar E3 Kerogen 2 Z1 C1 + Z2 kerogen 3 Kerogen 3 E4 p. W1 C1 + W2 kerogen 4 and wherein non-HC gas represents non-hydrocarbon gases and HC represents hydrocarbon gases.   4) Basin modeling method in which the quantities of hydrocarbons present in source rocks and reservoir rocks are estimated using the method of claim 1.   5) A basin modeling method according to claim 4, wherein a kerogen conversion rate is measured from pyrolysis experiments, and then a kerogen conversion rate is determined from said reaction kinetic scheme, and a correction to be applied to the measured conversion rates, NSOs im NSOs m 42 2906482, is deduced in order to define the expulsion episodes of the hydrocarbons as well as the composition of said hydrocarbons.   6) Method for modeling the thermal cracking of kerogen according to one of the preceding claims, wherein a reduction in the size of the reaction scheme is performed according to the conditions required by a field of application, by reducing the number of chemical classes by grouping said chemical classes.