Rock-Eval

Table 1. HS yields and Rock-Eval pyrolysis data on pellets and matrices from the Cl a evil I layers of the Ras-Draa deposit, ns non...

The Total Organic Carbon (TOC) content (Table 1), given by the Rock-Eval pyrolysis, varies between 0.30 % and 1.62 % in phosphatic pellets and between 1.22 % and 4.05 % in their adjacent matrices. 

Teichmuller, M., and B. Durand, Fluorescence microscopical rank studies on liptinites and vitrinites in peat and coals and comparison with results of the rock-eval pyrolysis. Int. Jour, of Coal Geology, 1983, 2 y pp. 197-230. 

NOTE Tmax parameter from Rock-Eval analysis as defined by Espitalid et al. (75). 

The results are described in several sections. The first section deals with gross variations in organic sulfur with maturity as determined by Py-GC. The relationship between organic sulfur and Rock-Eval Tmax is discussed in the second section. In the third section, yields from flash pyrolysis are used to determine kinetic parameters for the loss of precursors for organic sulfur and other compounds from the kerogen during maturation. The last section describes the maturity-related variations in organic sulfur pyrolysis products. 

Figure 3. Partial FID chromatograms (/z-Cg to n-C9 region) from flash pyrolysis of Monterey Fm. kerogens, Santa Barbara basin. Open and closed circles indicate w-alk-l-enes and /z-alkanes respectively. Depth of burial, Rock-Eval pyrolysis Tmax, Hydrogen Index (HI), and the thiophene ration (TR) are shown.

Relationship between Maturity. Rock-Eval Tmax and Organic Sulfur content... 

The relationship between Rock-Eval Tmax and depth for the different sedimentary sequences is depicted in Figure 8. For a given sequence... 

Figure 8. Relationship between Rock-Eval pyrolysis T and depth for samples from the four sedimentary sequences (modified after Eglinton et al., 5). Continued on next page.

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 10. FPD chromatograms from flash pyrolysis of Mahakam coals. Sample depth, vitrinite reflectance, Rock-Eval Tmax, hydrogen index (HI) and the thiophene ratio (TR) are shown. Peak identifications are given in Table V.

Victorian brown coal occurs in five major lithotypes distinguishable by color index and petrography. Advantage has been taken of a rare 100 m continuous core to compare and contrast chemical variations occurring as a function of lithotype classification. For many parameters there is a much greater contrast between the different lithotypes than there is across the depth profile of (nearly) identical lithotypes. Molecular parameters, such as the distributions of hydrocarbons, fatty acids, triterpenoids and pertrifluoroacetic acid oxidation products, together with gross structural parameters derived from IR and C-NMR spectroscopic data, Rock-Eval and elemental analyses and the yields of specific extractable fractions are compared. 

C) Rock-Eval Pyrolysis - was performed on the samples using the equipment and techniques outlined in (11). The technique employs automated equipment providing controlled heating (25°C/min) of the sample under N2 from ambient to 550°C with subsequent detection and quantitation of evolved hydrocarbons and CO2. 

J. Espitalie and G. Maciel are thanked for providing access to Rock-Eval and solid state NMR facilities. G. Eglinton and J. K. Volkman are thanked for access to GC/MS facilities. 

Espitalie J. and Bordenave M. L. (1993) Screening techniques for source rock evaluation tools for source rock routine analysis Rock-Eval pyrolysis. In Applied Petroleum Geochemistry (ed. M. L. Bordenave). Editions Technip, Paris, France, pp. 237-261. 

Hartman-Stroup C. (1987) The effect of organic matter type and organic content on Rock-Eval hydrogen index in oil shales and source rocks. Org. Geochem. 11, 351-369. 

Katz B. J. (1983) Limitations of Rock-Eval pyrolysis for typing organic matter. Org. Geochem. 4, 195-199. 

Newman J., Price L., and Johnston J. H. (1994) Source potential of New Zealand coals, based on relationships between conventional coal chemistry, Rock-Eval pyrolysis, and GCMS biomarkers. 1994 New Zealand Petroleum Conference Proceedings The Post Maui Challenge Investment and Development Opportunities, p. 47 (abstract). 

Initially kerogens were divided into four major types as illustrated on this diagram with well-defined boundaries, (b) With the development of the Rock Eval pyrolysis system it was found that the HI and 01 indicies were directly proportional to the H/C and O/C ratios and therefore a plot of HI to 01 could be used to replace the H/C and O/C values on the Tissot-Welte diagram (Hunt, 1996) (reproduced by permission of Freeman from Petroleum... 

The initial result from Rock Eval pyrolysis is a chromatogram with the two major peaks described above. Si and S2 (Figure 4), along with the S3 peak. As the maturity of a sample increases, the temperature at which the Si peak appears remains relatively constant however, the temperature at which S2 maximizes increases. S3 is not used directly for maturity determinations. The increase in the temperature at which S2 maximizes results from the fact that what is being measured here is the temperature at which the residual material in the rock breaks down. As the maturity level of the rock increases, the temperature required to degrade the residual material also increases. It is important to note that a direct correlation between Tmax vitrinite reflectance is not necessary. 

Figure 4 Rock Eval pyrolysis typically produces three major peaks that are used extensively in geochemical characterization of source rocks. The most recent version of the system produces additional data but for most routine analyses the peaks of interest are the Si, S2, and S3 peaks as shown here. Various production parameters can be derived from these peaks plus values for HI and OI indicies.

Present-day reservoir or source rock temperature. 1 ppm — 1 pg g of rock. Hydrogen index HI — mg hydrocarbons produced per gram of TOC by ROCK EVAL pyrolysis of pre-extracted rock powder. ROCK EVAL parameter. Vitrinite reflectance. 

Price L. C., Pawlewicz M. J., and Daws T. (1999) Organic metamorphism in the California petroleum basins Chapter A. Rock Eval and vitrinite reflectance. US Geol. Surv. Bull. B 2174-A, 34pp. 

The total oil yield obtained from the shale upon pyrolysis is usually measured by the standard Fisher assay. However, it is possible to obtain a fast and accurate measurement of the oil yield by using the Rock Eval source rock analyzer (5), which operates on small quantities of rock, such as 50 or 100 mg. Figure 3 shows the comparison between the value obtained from the Rock Eval pyrolysis and the yield of the Fisher assay on the Toarcian shales of the Paris Basin. 

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