Groundwater flow in response to ground surface topography, erosional rebound, and hydrocarbon generation in Cretaceous strata in the Alberta Basin, Canada

The hydrodynamics and hydrochemistry of two Upper Cretaceous sandstone aqui fers, the Brazeau-Belly River and the Cardium aquifer, are compared in a st udy area in the west-central part of the Alberta Basin. The results show th e compartmentalisation of each aquifer into zones of different fluid satura tion and pressure distribution, large areas being abnormally pressured. Thi s implies the existence of lateral low-permeability barriers, which are cre ated by lithofacies changes and the decrease of relative permeability to wa ter at the water-hydrocarbon interface. Various mechanisms drive how in Cre taceous units in the area. Flow in the Brazeau-Belly River aquifer has most ly adjusted to the present-day topography, whereas pressures in the Cardium aquifer are mainly governed by hydrocarbon generation in the deep basin an d erosional rebound of the surrounding shales. (C) 2000 Elsevier Science B. V. All rights reserved.