Kerogens Type

Schimmelmann A, Lewan MD, Wintsch RP (1999) D/H ratios of kerogen, bitumen, oil and water in hydrous pyrolysis of source rocks containing kerogen types I, II, IIS and III. Geochim Cosmochim Acta 63 3751-3766... 

Figure 9. Relationship between the thiophene ratio, TR, and Rock-Eval Tmax f°r samples °f varying kerogen type. NB. All samples are immature with respect to oil generation (i.e. vitrinite reflectance, R0 < 0.5%).

Figure 13 The importance of activation energies for each kerogen type is further exemplified by Hunt (1996), who showed oil generation curves for different kerogen types in a pull apart basin and a cratonic basin with geothermal gradients of 45 °Ckm and 25 °C km , respectively (Hunt, 1996) (reproduced by permission of Freeman from...

Ganz H. and KalMeuth W. (1987) Application of infrared spectroscopy to the classification of kerogen-types and the evaluation of sotrrce rock and oil shale potentials. Fuel 66, 708-711. 

Figure 14.4.2. Kerogen typing based on Py-GC/MS data (xylene/octene ratio).

Chemical changes in coal during its evolution through the different rank stages can be compared with the evolution of various kerogen types. The greatest chemical and evolutionary similarities are observed between coal and type III kerogen. 

Previous analyses (20) of the three principal kerogen types (i, II, III), obtained by monitoring the fragment ions with m/z values of 91, 105 and 119 had indicated, in a preliminary fashion, that the mass chromatograms provided a useable fingerprint of alkylbenzene moieties for each kerogen type. 

Espitalie, et al. (10) studied the pyrolysis of various kerogen types in mixtures with various minerals in addition to pyrolysis experiments on the source rocks for the kerogens. They concluded that the minerals act as a heavy hydrocarbon trap, in effect, limiting the possible yield of hydrocarbons from source rocks. They also found that carbonate minerals have a lower specific activity for the trapping phenomenon than do silicate minerals. 

Table 4.8 Bulk compositional changes in the three main kerogen types with increasing maturity (after Behar Vandenbroucke 1987). Maturity levels are shown by positions of samples in Fig. 4.15. Type I kerogen is based on the Eocene, upper Green River Formation shale from the Uinta Basin type II is based on theToarcian shales of the Paris Basin (France) and Liassic a shales from Germany and type III on the deltaic sequences from the Upper Cretaceous of the Douala Basin (Cameroon) and from the Tertiary of the Mahakam Delta (Borneo)...

Fig. 4.15 A van Krevelen plot showing the evolutionary trends of the main kerogen types (shaded bands after Behar Vandenbroucke 1987) and most coals (between solid lines after Killops etal. 1998). With increasing maturity kerogens follow a path towards the origin, as shown for the low/high-H coals boundary.The main hydrocarbon-generation zones are shown, with their approximate rank boundaries (as vitrinite reflectance values, %Ro), together with the effect of loss of various volatiles from different kerogen compositions (CH2 = oil). Points represent the composition of kerogens in Fig.4.14.

Fig. 4.19 Distribution of hydrocarbons generated from different kerogen types at the peak of oil formation.Areas are proportional to amount of hydrocarbons per unit mass of organic carbon (after Tissot Welte 1984).

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