Patent ID: 7388811

Claim:
A method of active seismic monitoring of an underground formation providing separation of induced microseismicity signals from seismic signals emitted during active seismic monitoring of an underground zone under development, the induced microseismicity signals and the seismic signals being obtained only during the active seismic monitoring, comprising carrying out seismic recording cycles with emission of seismic waves in the formation by coupling therewith at least one seismic source, which emits simultaneously orthogonal signals so as to form a composite vibrational signal, receiving signals reflected by the formation in response to the emission of seismic waves, recording the signals received by at least one seismic pickup and processing the recorded signals to separate respective contributions of each seismic source to the received signals and to reconstruct seismograms equivalent to seismograms that would be obtained by separately actuating each seismic source, separating the induced microseismicity signals in the records from seismic signals resulting from active monitoring operations, by isolating a contribution thereof by comparison with a current spectral model, the current spectral model being formed by updating a previous spectral model using a weighted average of current and previous contributions of each seismic source, and by reconstructing the microseismicity signals by inversion in the time domain.