Assessment of focal mechanisms of microseismic events computed from two three‐component receivers: application to the Arkema‐Vauvert field (France)

We have developed a method that enables computing double‐couple focal mechanisms with only a few sensors. This method is based on a non‐linear inversion of the P, Sv and Sh amplitudes of microseismic events recorded on a set of sensors. The information brought by the focal mechanism enables determining the geometry of the rupture on the associated geological structure. It also provides a better estimate of the conventional source parameters. Full analysis has been performed on a data set of 15 microseismic events recorded in the brine production field of Vauvert. The microseismic monitoring network consisted of two permanent tools and one temporary borehole string. The majority of the focal mechanisms computed from both permanent tools are similar to those computed from the whole network. This result indicates that the double‐couple focal mechanism determination is reliable for both permanent 3C receivers in this field.