Kerogen transformation

Figure 1. Stages of kerogen transformation and hydrocarbon formation pathways in geological situations. Direct inheritange of low molecule weight compounds is indicated by block arrows (from Engel and Macko, 1993).

The pore-pressure profiles for the wells belonging to hydraulic compartments II and III show a rapid increase versus depth for the lowermost Cretaceous-Upper Jurassic interval (Figs. 4 and 14 red trend line). This pressure increase versus depth is higher than lithostatic, and is taken to suggest that the primary cause of overpressure for this interval is related to the pulse of increased maturation and pressure build-up within the Spekk Formation source rock caused by increased maturation and kerogen transformation to liquid hydrocarbons, again primarily in response to the Pliocene to Recent subsidence. 

What chemical alterations have occurred during kerogen transformation Give an example of a van Krevelen diagram. 

Fig. 5.51 Kerogen transformation at a constant heating rate of3°CMyr 1, based on single A plus discrete Eact distributions (after Tegelaar Noble 1994) for tasmanites (type I, Cretaceous, North Slope, Alaska), Monterey shale (type II—S, Miocene, Ventura, California), Kimmeridge Clay (type II, Jurassic, North Sea) andManville Formation (type III, Cretaceous, Alberta). Modelled vitrinite reflectance based on EASY%Ro (after Sweeney Burnham 1990 Table 5.5).

Fig. 5. 52 Examples of reaction networks of varying complexity that can be used to model kerogen transformation.

With regard to the Monterey kerogens there are some similar trends to those observed for the Mahakam coals although the transformations are... 

Marshall C. P., Wilson M. A., Hartung-Kagi B., and Hart G. (2001) Potential of emission Fourier transform infrared spectroscopy for in situ evaluation of kerogen in source rocks during pyrolysis. Chem. Geol. 175, 623-633. 

Increased knowledge of the molecular transformations which occur during oil shale pyrolysis (retorting) is essential for maximizing the yield and quality of products from this vast source of hydrocarbons. Compared to other sources such as petroleum and coal, there is little known about the molecular structure of the insoluble organic material (kerogen) in oil shale. There is... 

The temperature dependencies of these parameters reveal chemical and physical transformations that occur in the nature of the kerogen materials and the pyrolysis products. Examples of -H NMR thermal scanning of Australian oil shales are presented which illustrate this method of 1h NMR thermal analysis. 

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