Experimental and theoretical studies of drainage type unstable immiscible displacements in porous media in a gravity field.

摘要

In this study, the drainage type and unstable immiscible displacements in porous media were studied in depth, focusing on the influence of capillary and gravity forces on the morphology of fingers of the migrating nonwetting phase and DNAPL finger spacing under various conditions.;Experiments for the upward migration of air through a porous medium saturated with oil have been carried out in a rectangular, thin glass-bead-packed model to study the effect of experimental conditions, such as oil viscosity, density, oil saturation, and the size of the initial air-zone, on the displacement pattern of gas migrations, Results of air migration experiments in oil saturated porous media models with oil viscosities in the range 3 to 11 mPa;Computer simulations of unstable immersible displacements in porous media were carried out in two-dimensional and three-dimensional network models using percolation theory concepts and incorporating capillary and gravity forces to address DNAPL spill migration in water saturated media. Using invasion percolation for drainage type displacements, the effects of pore structure, pore size, pore size distribution, density difference ;Computer simulations of DNAPL migration in layered porous media were carried out in three-dimensional (3-D)network models.;The results of this work have applications in the following important problem areas: (1) estimation of the spatial distribution of DNAPL fingers in aquifers having homogeneous pore structure. Knowing the morphology of DNAPL fingers in a network model representative of the real pore structure, the DNAPL migration velocity can also be estimated using techniques available in literature. (2) estimation of secondary gas migration rates and (3) estimation of DNAPL saturation in homogeneous aquifers known the spill volume below the vadose zone. (Abstract shortened by UMI.)