International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

SEISMIC REFLECTION INVESTIGATIONS FOR GAS STORAGE IN AQUIFERS (MURA DEPRESSION, NE SLOVENIA)

Pages: 285 - 294

Authors: ANDREJ GOSAR

Abstract: Two antiform structures in the Mura Depression were investigated as the most promising in Slovenia for the construction of an underground gas storage facility in aquifers. Seventeen reflection profiles with a total length of 157 km were recorded, and three boreholes were drilled at their locations. Structural models based on interpretation of the reflection seismic data, were constructed for the two main horizons (the pre-Tertiary basement and the Badenian/Sarmatian boundary). Evaluation of different seismic velocity data was carried out to establish lateral velocity variations in order to perform correct time-to-depth conversion. The porous rock in the Pecarovci structure is a 70 m thick layer of dolomite, occurring at a depth of 1900 m, whereas layers of marl, several hundred meters thick, represent the impermeable cap rock. Due to faults, the Dankovci structure, at a depth of 1200 m where the reservoir rocks consist of thin layers of conglomerate and sandstone, was found to be less reliable. 1D synthetic seismograms were used to correlate the geological and seismic data at the borehole locations. Raytracing modelling was applied to confirm lateral continuity of some horizons and to improve the structural interpretation at the locations of faults, which are critical factors for the storage of gas.

Keywords: Pannonian Basin, Mura Depression, raytracing modelling, synthetic seismograms, gas storage, seismic reflection

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