Interpreting Rock-Eval Pyrolysis Data Using Graphs of Pyrolizable Hydrocarbons vs. Total Organic Carbon

Kerogen, the major organic component of sedimentary rocks, is commonly analyzed by Rock-Eval pyrolysis. Plotting the data on a graph of S2 vs. total organic carbon (TOC) and determining the regression equation is the best method for determining the true average hydrogen index and measuring the adsorption of hydrocarbon by the rock matrix. Such a plot also indicates the type of kerogen present and avoids the problem of increasing hydrogen index with total organic carbon content. With the S2 vs. TOC diagram, the organic component of different suites of samples may be compared and their petroleum-generation potentials established. As an example, the diagrams are used to evaluate the sedimentary environments and petroleum potential of the Paleogene evaporitic sediments of the Mulhouse basin, Alsace, France.