Print this pageAbstract: The Stenlille Aquifer Gas Storage, Denmark
FRANDSEN, NILS
Data for development of the Stenlille aquifer storage for natural gas were acquired from 2D seismic surveys and 18 wells drilled through the reservoir. The top of the reservoir sandstone (Gassum Formation) forms a flat, domal anticline. The structure has dip closure except at one side where it is fault-closed. Minor faults exist at the structure's crest being 1454 m below sea level. Vertical closure above structural spill point is 23 m corresponding to an area of 9.7 km2 and a potential storage capacity of 3.0 X 109 Nm3 (total) and 1.2 X 109 Nm3 (working).
Wireline logs - mainly gamma ray and neutron/density - show that the Gassum Formation correlates between all wells. Thickness is around 140 m. Log and core data show subdivision into laterally correlatable sandstone zones. Claystone intervals define zone boundaries.
The sediments were deposited in marine and coastal environments. Sandstones change upwards from estuarine to shoreline deposits. Claystones are lagoonal or fully marine sediments. Upwards increasing claystone frequency reflects change to fully marine conditions culminating with marine claystones of the Fjerritslev Formation forming seal for the gas storage.
5 reservoir zones are defined. Porosity and permeability of the main zones, 3 and 5, average 25-26% and 250-350 mD, respectively.
Gas is injected in Zones 1, 2, 3 and 5 in crestal wells. Increased zone pressures in peripheral wells confirm lateral continuity of zones. Gas is observed in all injection zones in crestal wells drilled after initiation of injection. RFT measurements in these wells confirm pressure increase in injection zones and indicate whether zones have pressure communication.
AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria