A preliminary 3-D numerical modelling of the Warsaw synclinorium Early Cretaceous reservoir

Abstract

The Early Cretaceous aquifer is a large sedimentary structure in the Great Poland depression, covering about 108,000 km2. In the Warsaw synclinorium, the depth to the Early Cretaceous layer varies from a few dozens metres to about 1500 m u.s.l. The thickness of this formation ranges from a few metres to 200 m maximum. Stratigraphically, the Early Cretaceous sediments are divided into two permeable sandstone layers separated by near-impermeable mudstone and clay layers. Permeability varies from 1.5 D in the deep part of the synclinorium to 8 D in the outcrops. The lower sandstone layer is of less permeability than the upper one. Regional flow in the reservoir is mainly from southeast to northwest. The static water level in wells drilled into the Early Cretaceous layer is at 50 m. The reservoir temperature varies from about 10-15 C in the southwestern outcrops to about 40-45 C in the deepest part. With the aid of the TOUGH2 simulator, a simple numerical reservoir model was set up for the Early Cretaceous reservoir. A 60 m3/hr production from one well, and the same re-injection rate to one or two other wells was simulated. No cooling is predicted for this well configuration, partly because of the long distance between the wells, and partly because of regional flow in the reservoir.