| Title | Use of Gravity Post-Processing and Accurate 3D Forward Modeling to Identify and Characterize Geothermal Target |
|---|---|
| Authors | Yassine ABDELFETTAH, Eva SCHILL |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | gravity, exploration, post-processing, Butterworth filter, Permo-Carboniferious graben, basement heterogeneities |
| Abstract | Among others, geothermal heat flow anomalies in central Europe may also be linked to graben structures at the top of the crystalline basement. Numerical thermo-hydraulic models have shown that these anomalies are linked to hydrothermal circulation on local and regional level. These so-called Permo-Carboniferious (PC) troughs present a challenge in exploration geophysics, since they show little difference in seismic impedance with respect to the crystalline basement. They are, however, characterised by low mean density compared to the crystalline basement. To demonstrate the potential of the gravity exploration method to characterize such as structures, accurate and detailed sensitivity analyses were conducted. The objective was to use the approach in qualitative and quantitative interpretation, mainly the gravity post-processing using accurate forward modelling and filtering. We would like to emphasize the added value of the application of the data filtering, and show the benefit of using full 3D finite element (FE) simulation, to identify and characterize these kind of structures. The sensitivity study shows that i) the gravity effects generated by shallower structures can be identified and separated from those generated by deeper one. ii) The application of the high- and band- pass Butterworth filter, allows for identifying the distribution of the PC grabens in the crystalline basement. iii) 3D forward modelling using FE discretization, in conjunction with gravity filtering using different wavelength of Butterworth filter is an important tool to characterize any density heterogeneities in depth. |