It has become increasingly apparent in recent years that understanding the organic/inorganic interface and the geobiochemical role of bacteria and clay minerals in sedimentary basins is crucial to development of accurate, comprehensive models of equilibrium and mass transfer in diagenetic processes. A myriad of reversible and irreversible reactions occur in these processes, all of which are in principle amenable to thermodynamic analysis. For example, thermodynamic calculations can be used together with compositional data to identify stable and metastable equilibrium states in diagenetic systems and assess kinetic constraints on reaction progress. Calculations of this kind can be carried out with the aid of equations of state developed in this laboratory over the past several decades. These equations make it possible to investigate the chemical and thermodynamic consequences of reactions among a wide variety of minerals, gases and aqueous species at elevated temperatures and pressures. The purpose of this proposal is to request long-range support for continuation of this research in the context of diagenetic processes with emphasis on organic/inorganic reactions and those of geobiochemical interest. The goals of the project over the next five years include comprehensive calculation of the thermodynamic properties of organic liquids, solids, gases and aqueous species as a function of temperature and pressure, investigation of the extent to which metastable equilibrium prevails among organic molecules in petroleum, aqueous species in oil field brines, and authigenic mineral assemblages in hydrocarbon reservoirs and source rocks, quantification of thermodynamic constraints on the role of bacteria in diagenetic processes at elevated temperatures and pressures, and calculation of mass transfer involving organic/inorganic reactions and clay minerals in sedimentary basins.
