Fluid pressure, flow velocities and transport processes in a consolidatingsedimentary column with transient hydraulic properties

Consolidation is the principal process in generating fluid overpressures an d fluid expulsion in a sedimentary column. While low sedimentation rates an d permeable sediments with low compressibilities create low fluid overpress ures and rapid compaction equilibrium, high sedimentation rates and low per meable sediments with high compressibilities such as shales inhibit fluid e xpulsion and contribute to elevated fluid pressures. Predictions of fluid o verpressures based on solutions of the consolidation equation need to take into account that hydraulic conductivity and compressibility in the sedimen tary column are varying with time and that the sediment column itself is su bject to deformation. Although flow velocities are low, the effect of advec tion on the vertical displacement of solutes within the consolidating colum n is important. This contribution presents numerical solutions of the equat ions for consolidation and solute transport in one dimension in space, taki ng into account the changing hydraulic properties of sediment during compac tion and the deformational shortening of the column. (C) 2000 Elsevier Scie nce B.V. All rights reserved.