This study integrates Micro-EarthQuake (MEQ) from surface data, MEQ from shallow buried receivers, MEQ from downhole receivers, depth imaging fracture volumes computed from the surface microseismic data, attributes computed from surface reflection seismic, and petrophysical data. Overlays of the MEQ with the surface seismic attributes show that the MEQ detections are more often detected in the zones where the fault tracker shows faults while the depth imaging microseismic fracture maps show finer details of the fracture systems and provide maps of how the larger fractures are connected. Overlays of the microseismic fracture maps on attribute maps computed from reflection seismic and petrophysical data indicate that the fractures that were opened by the frac pumping were controlled by the lithology and the brittleness of the rocks. Fewer fractures are opened in softer more ductile rocks, more fractures are opened in rocks that have higher impedance and are more brittle. Comparisons of the MEQ detected in surface data to those detected in downhole data show that more MEQ are detected in the downhole. The locations of the MEQ in downhole data are more scattered than the surfacedata in X and Y, for MEQ at large distances from the downhole monitor well. Comparisons of the MEQ detections to the microseismic fracture volumes show that the microseismic fracture volumes have more fracture detail than the maps of the MEQ alone. Both the downhole data and the microseismic fracture maps provide more fracture detail than the surface seismic derived fault tracks.
The microseismic fracture volumes are computed using a depth migration approach in which a full depth volume is computed for each time window. Thousands of depth volumes are computed and then integrated to build up the seismic emissions that occur over extended time intervals. Synthetics demonstrate the method and support the results observed in real data examples.