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2017 | Book

Global Chemical Kinetics of Fossil Fuels

How to Model Maturation and Pyrolysis

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About this book

This book covers the origin and chemical structure of sedimentary organic matter, how that structure relates to appropriate chemical reaction models, how to obtain reaction data uncontaminated by heat and mass transfer, and how to convert that data into global kinetic models that extrapolate over wide temperature ranges. It also shows applications for in-situ and above-ground processing of oil shale, coal and other heavy fossil fuels. It is essential reading for anyone who wants to develop and apply reliable chemical kinetic models for natural petroleum formation and fossil fuel processing and is designed for course use in petroleum systems modelling. Problem sets, examples and case studies are included to aid in teaching and learning. It presents original work and contains an extensive reanalysis of data from the literature.

Table of Contents

Frontmatter
Chapter 1. Classification and Characterization
Abstract
The main types of sedimentary organic matter are described, including how they transform from one form to another during progressive burial in the subsurface and how they have been categorized over the past century. The historical usage of coal, bitumen, oil and natural gas is summarized from prehistoric times to the present. Characterization methods are reviewed, including optical, spectroscopic, elemental analysis, pyrolysis, and chromatographic methods.
Alan K. Burnham
Chapter 2. Introduction to Chemical Kinetics
Abstract
After introducing the basis of the Arrhenius equation and its relationship to transition-state theory, forms of global chemical kinetic models are summarized, including shrinking core and pseudo nth-order reactions; sigmoidal reactions such as sequential, random scission, autocatalytic, logistic, and nucleation-growth model; and distributed reactivity models, including continuous and discrete activation energy distribution models. Isoconversional and model fitting methods for deriving chemical kinetic models are described, including how to use simple kinetic analyses to derive initial guesses for nonlinear regression of complex models. Common errors that lead to erroneous Arrhenius parameters are outlined.
Alan K. Burnham
Chapter 3. Structures of Coal, Kerogen, and Asphaltenes
Abstract
Hypothetical molecular structures of humic coal, sapropelic kerogens, and asphaltenes are described, including how they change with maturity and how they have been refined over the past 75 years with advances in characterization methods. Due to their importance for modeling oil and gas expulsion, Hildebrand solubility theory and results are outlined. The relationship between aromaticity and coke yield is described. A link is made also between the fundamental mechanism of kerogen decomposition and the types of appropriate global chemical kinetic models.
Alan K. Burnham
Chapter 4. Pyrolysis in Open Systems
Abstract
Methods are reviewed for how to measure pyrolysis kinetics under atmospheric or lower pressure. The effects of heat and mass transfer on apparent chemical reaction rates are discussed, including limits for heating rates and sample size and geometry that result in the sufficiently accurate temperature measurements. Evidence for sequential versus parallel reaction mechanisms is described, including common misinterpretations in the literature. The competition between oil and tar vaporization and coking is outlined, including how it affects product yields and composition. Kinetic parameters for coal, sapropelic kerogens, and asphaltenes are reviewed, with the conclusion that principal activation energies outside the range of about 50–56 kcal/mol are not credible. Relevant global models range from sigmoidal to distributed reactivity depending on the kerogen structure.
Alan K. Burnham
Chapter 5. Pyrolysis in Semi-Open Systems
Abstract
Effects of pressure on product transport and enhanced secondary reactions are described, including simple ways of modeling them and the beneficial effect of H2. Fractionation of molecular types during vaporization is summarized. Cracking kinetics for oil and model compounds are reviewed. Nearly all results are consistent with an effective activation energy of 56–60 kcal/mol, although a higher energy may be appropriate at the low temperatures and higher pressures associated with cracking in the subsurface. The consequences of ignoring isoconversional character are described.
Alan K. Burnham
Chapter 6. Pyrolysis in Closed Systems
Abstract
The reactions of coal and sapropelic kerogen in a closed system are reviewed. A range of chemical kinetic models that include primary and secondary reactions are described, including compositional models of vitrinite reflectance. Again, the primary hydrocarbon generation reactions are consistent with activation energies in the 50–56 kcal/mol range. Diverse published values from hydrous pyrolysis are shown to be caused by inadequate separation of transport and distributed reactivity effects. Oil composition fractionation from hydrous pyrolysis is shown to be similar to that in semi-open pyrolysis. Effects of hydrogen and hydrogen donors are also discussed, including kinetics for coal liquefaction and oil shale thermal solution.
Alan K. Burnham
Chapter 7. Applications to Fossil Fuel Processes
Abstract
The use of global chemical kinetics to model petroleum formation and primary migration, oil shale retorting, coal liquefaction, and coal combustion is described. The history of reasonable prediction of petroleum generation is reviewed, including how the qualitative models developed in the 1970s were transformed into quantitative models in the 1980s. Differences in geological oil generation temperatures for different kerogen types are shown, as well as the coupling between oil and gas retention by kerogen and the resulting effects of fractionation and secondary reactions. Similarities and differences between oil shale retorting below and above ground are reviewed, including how the competition between heat transfer and chemical reactions affects product yields and quality. Current efforts on coal liquefaction and modeling of pulverized coal combustion are described briefly.
Alan K. Burnham
Backmatter
Metadata
Title
Global Chemical Kinetics of Fossil Fuels
Author
Alan K. Burnham
Copyright Year
2017
Electronic ISBN
978-3-319-49634-4
Print ISBN
978-3-319-49633-7
DOI
https://doi.org/10.1007/978-3-319-49634-4