A Study of Rock-Water Interaction and Simulation of Diagenesis in the Upper Almond Sandstones of the Red Desert and Washakie Basins, Wyoming
Indu D. Meshri, Jana M. Walker, 1990. "A Study of Rock-Water Interaction and Simulation of Diagenesis in the Upper Almond Sandstones of the Red Desert and Washakie Basins, Wyoming", Prediction of Reservoir Quality Through Chemical Modeling, Indu D. Meshri, Peter J. Ortoleva
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Chemical modeling of the rock-water interactions in the Upper Almond Sandstone within the context of burial (thermal) history of these rocks predicts the petrographically observed sequence of cementation to a fair degree.
The depositional environment of the Upper Almond Sandstone is believed to have been a barrier bar of Late Cretaceous age. Therefore, initial pore-water chemistry is assumed to be a function of seawater composition and, consequently, marks the starting point of diagenesis.
Present-day water compositions along with a knowledge of depositional environment assist in further deduction of early pore-water composition as one-third diluted seawater. Formation waters collected from the Upper Almond Sandstone in the Wamsutter area are distinguished from waters of the underlying Main Almond Sandstone on the basis of total dissolved solids, <5180, log-derived salinities, and pressure-depth profiles.
The main objective of this study was to test the predictive capability of the existing computerized chemical modeling approach to elucidate diagenesis in the Upper Almond Sandstone. Having noted the chemical processes leading to the simulation of the observed diagenetic sequence, one can follow a similar logic to explore deeper or shallower for similar lithologic units.
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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.