The evolution of the electronic absorption edge of type I, II and III kerogen is studied by diffuse reflectance UV–Visible absorption spectroscopy. The functional form of the electronic absorption edge for all kerogens measured is in excellent agreement with the ‘‘Urbach tail’’ phenomenology. The Urbach decay width extracted from the exponential fit within the visible range is strongly correlat...

Three types of pathways (degradation–recondensation, natural sulphurization and selective preservation) are commonly considered for the formation of kerogen dispersed in sedimentary rocks. A fourth pathway has been recently put forward, however, from studies on Recent marine sediments, the so-called sorptive protection mechanism. This pathway is based on the adsorption of otherwise labile organ...

The kerogen of an organic-rich sample, termed f top, from the Gorodische section (Russian platform) was studied using a combination of microscopic, spectroscopic and pyrolytic methods so as to examine its chemical structure, source organisms and formation pathway(s). This kerogen, which is mainly composed of orange gel-like, nanoscopically amorphous organic matter, exhibits a relatively high al...

A big challenge in studying organic rich shale is to predict its kerogen content and maturity from indirect observations. Kerogen maturation changes shale texture; for example, it generates microcracks and fractures in the matrix. Assessment of maturity from indirect measurements can be greatly enhanced by exploiting any existing correlations between physical properties, microstructure, and ker...

The most important types of organic matter in geosphere have already been mentioned. These are the fulvic and humic acids, humin, kerogen (in coal, oil shales, source rocks or scattered in the sediments), bitumen, oil, gas and graphite. All these forms are genetically related and are part of the carbon cycle in nature, or carbon cycle in the geosphere (larger circle in Fig. 1.4). Central place ...

Hydrocarbons are the main components in natural gases. Although the molecular distribution has been often used to study the origin of hydrocarbon, the occurrence of pentane and hexane isomers has not been discussed for natural gases. This study first reports controlling factors of pentane and hexane isomer ratios of natural gases from Akita, Niigata and Hokkaido in Japan. For the samples from A...

The most important types of organic matter in geosphere have already been mentioned. These are the fulvic and humic acids, humin, kerogen (in coal, oil shales, source rocks or scattered in the sediments), bitumen, oil, gas and graphite. All these forms are genetically related and are part of the carbon cycle in nature, or carbon cycle in the geosphere (larger circle in Fig. 1.4). Central place ...

The most important types of organic matter in geosphere have already been mentioned. These are the fulvic and humic acids, humin, kerogen (in coal, oil shales, source rocks or scattered in the sediments), bitumen, oil, gas and graphite. All these forms are genetically related and are part of the carbon cycle in nature, or carbon cycle in the geosphere (larger circle in Fig. 1.4). Central place ...

The process by which organic matter decomposes deep underground to form petroleum and its underlying kerogen matrix has so far remained a no man's land to theoreticians, largely because of the geological (Myears) timescale associated with the process. Using reactive molecular dynamics and an accelerated simulation framework, the replica exchange molecular dynamics method, we simulate the full t...

Concentrations of organic acids ranging up to several thousand parts per million have previously been found in oil-field waters. These acids are of interest because of their potential to enhance porosity by the dissolution of carbonates and aluminosilicates. They are believed to be generated from organic geopolymers (kerogen) in the late-diagenetic-early-catagenetic stage of thermal maturation....