METHOD OF USING SEMBLANCE OF CORRECTED AMPLITUDES DUE TO SOURCE MECHANISMS FOR MICROSEISMIC EVENT DETECTION AND LOCATION

摘要

A method for determining hypocenters of microseismic events includes entering as input to a computer seismic signals recorded by a plurality of seismic sensors disposed proximate a volume of subsurface to be evaluated. For each point in space in the volume, and for a plurality of preselected origin times, a seismic energy arrival time at each seismic sensor is determined. Event amplitudes for each arrival time are determined. A synthetic event amplitude is calculated for each arrival time. A semblance between the determined event amplitudes and the synthetic event amplitudes is determined. Existence of an actual microseismic is determined event when the semblance exceeds a selected threshold.

主权项

1. A method for determining hypocenters of microseismic events, comprising:
entering as input to a computer seismic signals detected by a plurality of seismic sensors disposed proximate a volume of subsurface to be evaluated; in the computer, for each point in space in the volume, for a selected seismic velocity model and for a plurality of preselected origin times, calculating an expected arrival time of seismic energy at each seismic sensor position; in the computer, determining event amplitudes for each arrival time from the detected seismic signals; in the computer, calculating a synthetic event amplitude for each arrival time; in the computer, calculating a semblance using the determined event amplitudes corrected using the synthetic event amplitudes; in the computer, determining existence of at least one actual microseismic event when the semblance exceeds a selected threshold; and displaying or recording a position and origin time of the at least one actual microseismic event.