Exploration-relevant sandstones of the Bückeberg Group in Lower Saxony 1 : 500 000 - Transmissibility from drill core data
Description
The overview map shows the distribution of the Bückeberg Group (Lower Cretaceous, Upper Berriasium) in the Lower Saxony Basin and shows in particular exploration-relevant sandstones and their properties. Regionally contiguous sandstones with a thickness of at least five metres are considered to be relevant for exploration. For these units, a potential as geothermally usable aquifers can be assumed, but this must be demonstrated on a site-specific basis in individual cases. The breakdown used here into the ‘upper’, ‘middle’ and ‘lower’ Bückeberg groups for the charted units is informal and relative. Exploration-relevant sandstones of the Berriasium are mainly found in the eastern part of the Lower Saxony Basin (head sandstone of the Fuhse Formation, sandstones of the Barsinghausen Subformation and sandstones of the Deister and Fuhse Formation) and occasionally in the Osnabrück area (sandstones of the Oesede Formation). The sandstones are usually embedded in an alternating sequence of claystone, siltstone and locally low-powered coal layers. Claystones, siltstones, clay marlstones, schill limestones and locally small sandstones of the Isterberg Formation are summarized. Porosity, permeability and transmissibility of lithologies were not taken into account in the mapping, but are reported as drilling-related parameters where available. The delineation of the mapped units is based on existing literature and the evaluation and interpretation of selected geoscientific data available at the State Office for Mining, Energy and Geology (LBEG).
It is based on the Paleogeographic Atlas of the Lower Cretaceous of Northwest Germany (Schott; 1969), which presents the distribution and lithology of the Lower Cretaceous in the Lower Saxony Basin, as well as the Geotectonic Atlas of Northwest Germany and the German North Sea sector (Baldschuhn et al. 2001) and the geological map of Lower Saxony 1: 50 000 (GK50). The distribution limit of the "Wealden" mapped by Schott (1969) (corresponds largely to the Bückeberg group) as well as the areas eroded by the pelvic inversion were adopted into the present map and modified in places according to more recent information. The salt structures shown are taken from the map of the salt structures of northern Germany 1: 500 000 (BGR 2008).
Within the distribution limit of the Bückeberg Group, deep drilling with suitable data was selected for mapping based on information from the LBEG hydrocarbon drilling database. The delineation of the mapped units is based on the evaluation and interpretation of stratigraphic and lithological information from strata inventories, geophysical well measurements and drill core material. Large-scale gearing or transition areas between two mapping units are shown as obliquely hatched surfaces. The superimposition of two sandstone units is shown as a vertical hatched area. Areas where no or insufficient information from deep drilling is available or has been evaluated are identified in the distribution map as ‘areas with insufficient lithology knowledge or not mapped’. The areas of the saline flanks and saline edges were not investigated in detail. Local changes in thickness, lithofazies and rock properties in these areas are therefore not taken into account.
The boreholes used are listed as supporting points. The evaluated data of the deep boreholes are displayed as value classes. The depth and overall thickness are based on the evaluation of the shift directories. Information on the thickness of the sandstones comes from the evaluation of borehole measurements as well as from the stratum inventories and refers to the thickest sandstone layer of an evaluated borehole. Sandstone porosity and permeability were calculated from the hydrocarbon database information from drill core data and, if available, borehole measurements. The information on porosities from drill core data is to be understood as effective porosities (%) and from drill hole measurements as total porosity (%). The value classes of permeability are given in millidarcy (mD) and in square meters (m2). In the maps, the different data bases are marked by symbols. The transmissibility of the sandstones results from their thickness and the respective permeability and is shown according to the calculation basis in different symbols in the units darcymeter (Dm) and cubic meter (m3).
Resources
| Name |
Format |
Description |
Link |
|
0 |
|
https://nibis.lbeg.de/net3/public/ogc.ashx?NodeId=1330&Service=WMS&Request=GetCapabilities& |