Patent ID: 8612155

Claim:
A method of detecting and locating a microseismic event, comprising: providing an estimate of a velocity model for a formation; estimating a volume of space in which the microseismic event will most likely occur; dividing the volume into a plurality of sub-volumes; receiving data of the microseismic event with at least a first and a second seismic sensor located on a tool in a wellbore; approximating a location of the microseismic event in the volume to determine in which sub-volume the microseismic event occurred, based on the received data; applying a first grid search, based on the approximated location of the microseismic event, to derive a residual function over a finer sampling in the volume, the residual function being indicative of difference between received and modeled data and having a term for penalizing consideration of candidate locations with undesired spatial positions and/or waveform contents; applying a gradient search of the residual function to optimize the location of the microseismic event; and determining a more precise location of the microseismic event based on the gradient search; wherein the act of approximating comprises maximizing a CMM (coalescence microseismic mapping) objective function suitable for non-vertical sensor array over a time interval and a spatial volume; wherein the CMM objective function includes azimuth and dip of incident wave, said azimuth and dip having different factors for controlling discrimination sharpness.