Effects of Fluid and Rock Compositions on Diagenesis: A Modeling Investigation
Craig H. Moore, Peter J. Ortoleva, 1990. "Effects of Fluid and Rock Compositions on Diagenesis: A Modeling Investigation", Prediction of Reservoir Quality Through Chemical Modeling, Indu D. Meshri, Peter J. Ortoleva
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In order to demonstrate the potential use of geochemical modeling using nonequilibrium, coupled reaction-transport codes in predicting reservoir quality, we have carried out simulations of four generalized systems using the REACTRAN computer code. The systems chosen contained “clean” and “dirty” arkoses and were subjected to alteration by fresh and saline waters at a constant temperature of 110°C. We show the results of these simulations at various times during the first 10 million years of diagenesis and describe the salient geochemical features leading to the spatial and temporal distributions of authigenic minerals.
The timing and extent of diagenetic events simulated here is a function of initial rock composition, the rate of fluid flow, and the rates of mineral dissolution and precipitation assumed here. When appropriate rate data is included as a function of temperature and pH, one anticipates a good comparison of simulated and observed diagenetic events. The prediction of the timing and the extent of diagenetic events is the key to the prediction of reservoir quality.
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Prediction of reservoir quality ahead of the drill is one of the most complex problems facing exploration geologists, especially when they are exploring in frontier basins, where rock and water data are minimal or non existent. Although useful descriptive models of diagenesis have existed in the past, they cannot be applied in the areas where rock and water data do not exist. This volume comes out of a 1987 conference oand contains 10 chapters that document the substantial progress made toward the goal of modeling reservoir quality. One facet of chemical modeling, namely porosity prediction, is the thrust of this book. However, chemical modeling has contributed heavily in the field of environmental geochemistry, nuclear waste disposal, and in the thermal recovery of heavy oil and the like, thus one such chapter is included in this memoir.