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

Abstract

Consolidation is the principal process in generating fluid overpressures and fluid expulsion in a sedimentary column. While low sedimentation rates and permeable sediments with low compressibilities create low fluid overpressures and rapid compaction equilibrium, high sedimentation rates and low permeable sediments with high compressibilities such as shales inhibit fluid expulsion and contribute to elevated fluid pressures. Predictions of fluid overpressures based on solutions of the consolidation equation need to take into account that hydraulic conductivity and compressibility in the sedimentary column are varying with time and that the sediment column itself is subject to deformation. Although flow velocities are low, the effect of advection on the vertical displacement of solutes within the consolidating column is important. This contribution presents numerical solutions of the equations for consolidation and solute transport in one dimension in space, taking into account the changing hydraulic properties of sediment during compaction and the deformational shortening of the column.