A multi-process basin and reservoir simulator: Effects of multi-mineralic diagenesis, pressure solution, and textural dynamics.

摘要

Factors affecting the formation of diagenetically produced hydrologic seals and fluid compartments are evaluated using a quantitative computer model accounting for mechano-chemistry, finite rate (kinetic) and equilibrium reactions and complex textural dynamics in one and two spatial dimensions.; A computational simulator CIRF.B (Chemical Interaction of Rock and Fluid, Basin), developed in conjunction with this dissertation, incorporates a multimineralic pressure solution mechanism in the form of a water-film diffusion model. The model also accounts for diagenesis at grain faces in contact with the pore fluid. Diagenetic kinetic reaction rates depend on mineral and pore water compositions as well as mineral texture; pressure solution rates depend on these factors, the thickness of water-film at grain-grain contacts, diffusion coefficients of solute within that water film, and stresses on grain surfaces.; Other important reaction-transport-mechanochemical phenomenologies in the model include the equation of state and conservation of water for pore fluid pressure and velocity calculations, lithostatic and effective stress equations, and textural dynamics using a truncated sphere model that allows pore-filling authigenetic mineralization. While chemical interaction is at the core of the model, it has been designed to apply to realistic basin studies by allowing the utilization of variable hydrologic and basin evolution histories.; The model's functionality is demonstrated through simulations of heterogeneous reservoirs and basins of both simple and complex geologic histories. Results of these simulations show that diagenetic seals and overpressured compartments can form in typical geologic conditions due to chemical compaction of sediments over geologic time. The results also show that, because the model preserves the nonlinearity and the coupling of the processes, it can capture the evolution of self-organizing patterns in otherwise uniform, unpatterned geologic systems.