Microseismic events are typically monitored using either a string of 3 component sensors within a single borehole or a widely spaced network of sensors at the surface or downhole. Any combination of sensor configurations can be processed simultaneously in Divine. At the Soultz geothermal project the stimulation of three boreholes, GPK2, GPK3 and GPK4 were monitored using a sub-surface network as illustrated above. The events were located using P and S traveltime observation alone. The contact between the GPK2/3 microseismicity with the GPK4 events is illustrated by the contact between the GPK2/3 event density contour plots and the gPK4 event symbols.
In geothermal applications event rates can exceed 200 events per hour. To process such high data rates in real time a proprietary automatic technique has been developed which is referred to as the Bootstrap method. In tests with event data from a sensor network, the Bootstrap method successfully processed all the events that could be identified visually. Divine also incorporates a range of trace display facilities that enable P and S times to be efficiently picked or checked interactively in a consistent manner which is important in obtaining reliable event locations.