The Impact of
Faults on Groundwater Flow Patterns in the Lower Rhine Embayment,
Bense, Victor1, Ronald Van Balen2
Faults have an important impact groundwater flow in the unconsolidated sediments of the Lower Rhine Embayment. In this area groundwater flow is strongly enhanced as a result of the dewatering of deep (>400 m), open-pit mines that are explored for lignite. Hydraulic head maps of this area show in detail how many individual faults form a barrier to fluid flow while relay structures in these faults are sites of hydraulic contact between otherwise separated aquifers. The Shale Gouge Ratio (SGR) algorithm that relates fault throw and clay content of the rock flanking the faults to its hydraulic properties, was used to understand the variations in hydraulic behavior of the faults in the study area in a systematic way. Although the application of this algorithm is now rather common in hydrocarbon related studies it had not been applied to groundwater flow data so far. Additionally, the effect of fault relay zones on fluid flow in the area is assessed using numerical simulations of groundwater flow. It is demonstrated that the SGR-methodology is a promising tool for the estimation of fault zone hydraulic properties in hydrogeological modeling. Moreover, we show the potential of groundwater flow data as an analog to fluid flow in deeply buried reservoirs offshore, to better understand the role of faults in hydrocarbon recovery related studies.