First compilation of stress magnitude data in Germany
A total of 568 data sets of stress magnitude data in the upper crust of the earth has been compiled, evaluated and made publicly available. The figure shows the distribution of the data in and around Germany. The data result mainly from hydraulic fracturing tests (37%), fluid pressure measurements in boreholes (20%) and from overcoring (17%). The data evaluation was done with a newly developed quality ranking scheme with the classes A-E and an X-class; an A-quality data record has a very high reliability and an E-quality data record is not usable; X-quality means that the necessary information is not available and the data record cannot be evaluated conclusively.
Stress magnitude data are fundamental for the reliable calibration of geomechanical numerical models of the 3D stress state prediction of the subsurface. The assigned qualities can be used for weighting during the calibration process. The data are inhomogeneously distributed and the quality in many regions is not sufficient to calibrate regional or local models. Therefore, we are currently working on an extension of the database through industry contacts and the validation of a multi-scale approach to be able to obtain reliable estimates of the absolute stress state from large-scale models for smaller ones.