Shale compaction and geopressure - an attempt to develop a unified model

Fluid transport in sedimentary basins is a well-known phenomenon. It happens due to stresses caused by tectonic events and/or gravitational force, due to sediment loading or erosion. Typically, if the loading process is rapid, fluid expulsion through compaction can be severely `retarded', especially, in fine-grained sediments with `low' permeabiliry, such as silts or clays. This results in stress re-distribution withm the column - a greater proportion of the overlying weight of the sediments is borne by the fluids than in the case had the sediments compacted normally, causing a decrease in the stress acting on the rock framework. This phenomenon is known to occur in most sedimentary, clastics basins (geopressure).