Coordinated Theoretical and Analytical Investigations of Organic Transformations During Diagenesis and Hydrothermal Alteration

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9418500 Shock Despite the enormous amount of research that has gone into characterizing the organic composition of geologic fluids, there still remains only a rudimentary understanding of the fundamental reaction pathways and mechanisms by which transformation occur when hot aqueous solutions interact with organic matter in natural processes. The emerging paradigm of metastable equilibrium provides a framework with which the dynamic relationships among organic compounds in geologic fluids such as oilfield brines and hydrothermal solutions is leading to a clearer understanding of the organic transformations responsible for the observed composition of these fluids, and has lead to new ideas about the origin, transport, accumulation and alteration of petroleum. The proposed research seeks to expand our knowledge of metastable equilibrium states, and improve their applicability for understanding geochemical processes. Specific issues to be addressed in the proposed research include: The breadth of metastable equilibrium states. At present, metastable equilibrium arguments are based largely on carboxylic acids in oilfield brines. Which other organic compounds present in natural solutions participate in metastable equilibrium states, and which do not? Do specific families of compounds reach metastable equilibrium, while others do not? The mechanistic implications of metastable equilibrium states. Can the observed metastable equilibrium relationships be used to construe the reaction pathways that actually occur in natural settings? The need for catalysts. Do the inferred pathways require the participation of a catalyst? What catalysts are available in these environments and in what from? To what extent do microorganisms catalyze these reactions? These issues are to be addressed through an approach that coordinates theoretical calculations with sampling and analysis of organic solutes in natural and experimental solutions. This effort will include: 1) collection and analysis of geologic fluids (initially oil-field brines) to achieve a more thorough inventory of their organic composition than is presently available, 2) incorporating these analyses into new tests of metastable equilibrium which will allow us to identify which compounds participate in metastable equilibria, 3) using the results of these calculations, identify the pathways by which organic compounds are transformed in natural settings, 4) comparison of these results with laboratory studies to identify which reaction pathways require catalysis, and 5) initiating the search for likely catalysts.