Maturity molecular parameters

Mackenzie A. S., Hoffmann C. E., and Maxwell J. R. (1981) Molecular parameters of maturation in the Toarcian shales, Paris Basin, France III. Changes in aromatic steroid hydrocarbons. Geochim. Cosmochim. Acta 45, 1345-1355. 

We have defined in-house calibrations of source roek maturity from various petroleum systems, assessed as source roek vitrinite reflectance equivalent as a proxy for maximum source rock temperature. The molecular parameter versus Ro% calibrations referred to below are either based on published source rock parameters we have validated to our satisfaction (e.g. Schaefer Littke 1988) or from in-house work on source rock maturity sequences. Inevitably, as all oils are mixtures we cannot accurately define point maturities for reservoired oils but by judicious choice of calibrant source-rock samples we feel the calibrations referred to are as robust as is possible in dealing with spatially and temporally complex entities such as source basins. The oil maturities we report are those interpreted classically based on correlations between measured oil molecular ratios and the... 

The studies discussed expand the use of the method for assessment of foetal lung maturity with the aid of microscopic foam bilayers [20]. It is important to make a clear distinction between this method [20] and the foam test [5]. The disperse system foam is not a mere sum of single foam films. Up to this point in the book, it has been repeatedly shown that the different types of foam films (common thin, common black and bilayer films) play a role in the formation and stability of foams (see Chapter 7). The difference between thin and bilayer foam films [19,48] results from the transition from long- to short-range molecular interactions. The type of the foam film depends considerably also on the capillary pressure of the liquid phase of the foam. That is why the stability of a foam consisting of thin films, and a foam consisting of foam bilayers (NBF) is different and the physical parameters related to this stability are also different. Furthermore, if the structural properties (e.g. drainage, polydispersity) of the disperse system foam are accounted for it becomes clear that the foam and foam film are different physical objects and their stability is described by different physical parameters. 

The transformations reviewed in Section 5.5 are potential maturity indicators.The most useful reactions are those in which only one of the pair of components is present initially in immature sediments, so that the extent of the transformation can be attributed entirely to thermal maturation (the kinetics of the transformation are also simpler Box 5.4). Such reactions include isomerization of pristane at C-6 and C-10, of steranes at C-20 and of hopanes at C-22, and also the aromati-zation of C-ring monoaromatic steroidal hydrocarbons. A number of molecular maturity parameters are shown in Fig. 5.47, together with some bulk maturity measurements.The correlation of values is approximate and varies with the type of organic matter present, its potential for generating petroleum and its heating rate. 

Various molecular maturity parameters, based on the positions of methylation of aromatic compounds, have been developed from studies of coals and type III kero-... 

Bishop A.N., Abbott G.D. (1993) The interrelationship of biological marker maturity parameters and molecular yields during contact metamorphism. Geochim. Cosmochim. Acta 57, 3661-8. 

Goossens H., de Lange F., de LeeuwJ.W., Schenk P.A. (1988a) The Pristane Formation Index, a molecular maturity parameter. Confirmation in samples from the Paris Basin. Geochim. Cosmochim.Acta 52, 2439—44. 

---