Rock-Eval pyrolysis

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. 

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.

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.

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. 

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. 

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. 

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. 

The organic hydrogen richness of the oil shales was assessed from Rock Eval pyrolysis data (Hydrogen index) which at high levels of organic richness can be considered to give reliable data (14, 15). 

Rock-Eval pyrolysis (Espitalie et al., 1977) was applied to immature ancient marine sediments by Herbin and Deroo (1979) and to recent marine sediments by Debyser and Gadel (1981). This technique results in information similar to elemental analysis, but the procedure is much faster, cheaper, and easier. However, it seems necessary to modify this method for use in recent sediments, where organic matter is thermally labile and rich in oxygen. This problem is currently under investigation at the Institut Francais du Petrole. 

Dembicki H.Jr. (1992) The effects of the mineral matrix on the determination of kinetic parameters using modified Rock Eval pyrolysis. Org. Geochem. 18, 531-9. 

Hydrogen Index (HI) values from Rock-Eval pyrolysis (see Sect. 4.5.2) below about 150 mg HC/g TOC are typical of terrigenous organic matter, whereas HI values... 

Rock-Eval pyrolysis (Espitalie et al. 1985) is conducted using bulk sediment samples to determine,... 

Determining the activation energy spectrum from Rock-Eval pyrolysis data is an inverse task of mathematical statistics having multiple solutions. Some problems are related to the restoration of chemical-kinetic parameters of effective reactions for organic matter maturation in source rocks. For example, reactions with activation energies of less than 50 Kcal moD do not contribute to the Rock-Eval pyrolysis Sj curve because these reactions can occur during the burial stage and would not contribute to S. ... 

The majority of organie matter in sediments eonsists of macromoleenles that cannot be characterized by usnal ehemieal analyses. Pyrolysis nses heat to break the large molecules into smaller molecnles that ean then be ehemieally identified. One type ofpyrolysis that has been shown to be of real value to paleolinmology is Rock-Eval pyrolysis, which was initially developed to evaluate the hydroearbon potential of petroleum source roeks (Espitali6 et al.. 

Hydrogen index (HI) An expression of the relative abundance of hydrogen with respect to carbon derived from RockEval pyrolysis of sedimentary organic matter. The hydrogen index is derived from measurement of the amount of hydrocarbon-rich material released by Rock-Eval pyrolysis of organic matter, divided by the TOC concentration of the sediment sample. It is a proxy for the atomic H/C ratio of organic matter. 

RockEval (also Rock-Eval, RockEval analysis) A rapid analytical method that utilizes pyrolysis to provide a semi-quantitative measure of the relative proportions of hydrogen, carbon and oxygen in bulk sedimentary organic matter. The instrument heats sediment samples to measure the amounts of hydrocarbons and hydrocarbon-like substances that escape at different temperatures from the organic matter contained in the sediment. The unit also calculates the amount of CO2 created during thermal decomposition of the organic matter. The results of Rock-Eval pyrolysis can help to identify the biotic sources of sediment organic matter. 

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