3D Seismic Exploration And Geological Factors Controlling The Permeability Structure Of The Faulted, Fractured And Karstified Upper Jurassic Carbonate Aquifer Fordeep Geothermal Energy Recovery In Theurban Region Of Munich

Abstract

The geomorphology of carbonate sedimentary systems at depth has always been enigmatic and difficult to fully understand and properly characterize. When it comes to geothermal reservoir characterization at considerable depth, a major aim is to describe as accurate as possible the spatial distribution of porosity and permeability (e.g. Fig. 1). Detecting high and low permeability structures in the reservoir is crucial for the long-term forecast of reservoir performance under varying injection and production schemes. Identifying and evaluating possible hydraulic barriers and conduits in the considered reservoirs and modelling the long-term thermal-hydraulic impact they have on the reservoir performance and management is a key goal of this work. Key geological controlling factors of the porosity and permeability distribution in carbonate reservoirs constitute lithofacies, biofacies, faults, fractures and diagenesis. These geological controlling factors determine the hydro- compartmentalization of the reservoir. This, in turn, traduces in significant heterogeneities and anisotropies in the permeability field. In this context, the larger the spatial extent of inhomogeneities, the stronger the effect they have on the flow and thermal simulation results. Small-scale heterogeneities should be handled by appropriate choice of effective homogeneous permeability. This work highlights the importance of 3D seismic surveys in obtaining a 3D image of the complex depositional system and structural geological features of the Upper Jurassic carbonate reservoir in the region of urban Munich. This is done based on results derived from 3D seismic interpretation of a recently conducted 3D seismic survey in urban Munich. In particular, the results obtained by the combination of several seismic attributes as well as the integration of shear wave analysis show the importance that this geophysical exploration technique has for the foreland basin geothermal play type. Aim and available data have a significant influence on the model architecture (e.g., mesh refinement with large permeability gradients – up to which level of detail must/can permeability heterogeneities and anisotropies be implemented?). This work focusses on an integrated approach combining information from 3D seismic interpretation and hydrotectonic considerations in urban Munich as well as a vast available data from geothermal wells in the surroundings of urban Munich to constrain the permeability structures that result from major structural geological features. This project has been granted by the Federal Ministry for Economic Affairs and Energy (BMWi).

AAPG Datapages/Search and Discovery Article #90345 © 2018 AAPG European Region, Geothermal Cross Over Technology Workshop, Part II, Utrecht, The Netherlands, April 17-18, 2018