Hermann Buness

Glacial structures in northern Germany revealed by a high‐resolution reflection seismic survey

In recent years, the sediments filling Pleistocene glacial structures have become of increasing importance to paleoclimate research. Climatic changes are documented by the deposition cycles in small, closed, trough or bowl-like structures. A 2-D, high-resolution, shallow reflection seismic survey was conducted in 1996 over such a structure near Tostedt in northern Germany. The objective was to obtain a more accurate picture of the structure and the underlying geology. Designed especially for shallow surveys, a newly developed impulse source provided sufficient energy to observe reflectors as deep as 400 m. Signals are characterized by a high-frequency content with maximum energy between 80 and 180 Hz. The migrated section shows a distinct reflection pattern revealing local glacial dynamics. Reflectors at depths of 30, 40, and 45 m from inside the Tostedt structure correlate well with three interstadials of the Weichselian period. Weak reflections define the bottom of the structure, with a maximum depth of 70 m. The structure is imbedded in a much larger, previously unexpected depression of similar shape. The fill of this larger depression is seismically nearly transparent. High-amplitude reflections delineate its lower boundary with a maximum depth of 130 m. Two major reflectors at depths of 170 and 270 m correlate with lower Miocene and middle Oligocene units. They indicate that subrosion, which might have been expected from the presence of a nearby salt diapir, is absent. This confirms the purely glacial origin of the two bowl-like structures.

The Heidelberg Basin drilling project: Geophysical pre-site surveys

Abstract. Currently, the Heidelberg Basin is under investigation by new cored research boreholes to enhance the understanding concerning the control on Pliocene and Quaternary sedimentation by (neo)tectonics and climate. The Heidelberg Basin is expected to serve as a key location for an improved correlation of parameters that characterise the climate evolution in North Europe and the Alpine region. The recovery of sediment successions of high temporal resolution that are complete with respect to the deposition of Pleistocene glacials and interglacials in superposition is of special importance. Prior to the new research boreholes in Viernheim and Heidelberg geophysical pre-site surveys were performed to identify borehole locations that best achieve these requirements. In the area of the Heidelberg Basin the strongest negative gravity anomaly of the entire Upper Rhine Graben is observed (apart from the Alps), hinting at anomalously thick sediment deposits. However, especially reflection seismic profiles contributed significantly to the decision about the borehole locations. In the city of Heidelberg for the first time, the depocentre of the Heidelberg Basin, as indicated by additional subsidence compared to its surroundings, was mapped. In this area, sediments dip towards the eastern margin of the Upper Rhine Graben. This is interpreted to represent a rollover structure related to the maximum subsidence of the Upper Rhine Graben in this region. At the Viernheim borehole location the seismic survey revealed several faults. Although these faults are mainly restricted to depths greater than 225 m, the borehole location was fi nally adjusted with respect to this information.

Fault imaging in sparsely sampled 3D seismic data using common-reflection-surface processing and attribute analysis – a study in the Upper Rhine Graben

ABSTRACT Cost reduction in seismic reconnaissance is an issue in geothermal exploration and can principally be achieved by sparse acquisition. To address the adherent decrease in signal/noise ratio, the common‐reflection‐surface method has been proposed. We reduced the data density of an existing 3D dataset and evaluated the results of common‐reflection‐surface processing using seismic attributes. The application of the common‐reflection‐surface method leads in all cases to an improvement of the signal/noise ratio. The most distinct improvement can be seen in the low fold regions. The improvement depends strongly on the midpoint aperture, and there is a tradeoff between reflector continuity and horizontal resolution. If small scale targets are to be imaged, a small aperture size is necessary, which may be far below the Fresnel zone for a specific reflector. The substantial reduction of the data density leads in our case to an irrecoverable information loss.

Sparse 3D Acquisition and CRS Processing for the Imaging of a Fault System: A Case Study

With increasing depth of coal mining observed increase in gas-bearing coal seams and their degree of outburst. It is known that foci of gasodynamic phenomena tend to be fractured zones of small-amplitude disturbances. Reliable determination of the location of these destructions in coal seams is an important task determining the safety of mining. We develop a seismic method of direct search of zones with open fractures in the coal seam and related centers storage of free methane, based on seismic monitoring and estimation of changing the stresses of the seam. The purpose of this monitoring is to find areas with a strong reaction to the geomechanical impacts due to, for example, moving the front clean-up operations. We are not interested in the structure of the stable part of the coal seam. Such an approach to mine seismic prospecting based on a combination of monitoring and active impact is formulated for the first time. We present numerical experiments for the model statement.

3D Seismic Exploration of a Carbonate Geothermal Reservoir in Southern Germany

The target of seismic exploration for geothermal energy within the Southern German Molasse Basin is the Upper Jurassic (Malm) carbonate platform. Several factors govern its hydraulic transmissivity. The formation of the platform led to different carbonate facies, i.e. reefs and small sedimentary troughs. Further on, fault systems play an important role since the formation of the basin was accompanied by complex faulting. Additionally, local carstification has taken place. A reservoir model of the aquifer has to take into account all of this geological heterogeneity. The seismic interpretation on the other hand has to provide the necessary geological information. Based on a 3D seismic survey a structural model was built, the facies distribution was analysed and carst structures were mapped. For these different tasks mathematical transforms have been evaluated.

Faults, Facies, and Karst - Intergrated Seismic Interpretation of a Hydro-geothermal Reservoir

Taking into account the heterogeneity of a hydro-geothermal reservoir, sedimentological and diagenetic information must be combined for a sound estimation of hydraulic parameters. Based on a newly processed 3D dataset from the Bavarian Molasse, we evaluat

Geothermal Exploration by 3D Seismic in Germany - Is There a Potential for Cost Reduction?

Seismic reconnaissance is required for deep hydro-geothermal reservoirs in Germany. To achieve cost reduction sparse acquisition of 3D seismic datasets has been proposed. To examine this approach, we simulated a sparse acquisition by reducing the data den

Structure and Facies Analysis of a Carbonate Hydrogeothermal Reservoir within the Southern German Molasse Basin

Geothermal energy is an increasing part of the worldwide energy supply. There are three geological provinces in Germany with hydrogeothermal potential: the North German Basin, the Upper Rhine Graben, and the Southern German Molasse Basin. Within the South