Patent ID: 8494777
Filing Date: 2013-07-23
Classification: G01V

Abstract:
1. 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 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 event by coalescing a plurality of seismic signals received with the receivers at selected locations and time in the volume to determine in which sub-volume the event occurred, the approximating comprising using coalescence microseismic mapping comprising an objective function suitable for non-vertical seismic sensor array; and determining a more precise location of the event by locating the event within the sub-volume utilizing the signals, the determining comprising using a linearized iterative inversion to determine the more precise location of the event within the sub-volume determined using the coalescence microseismic mapping; wherein the objective function includes azimuth and dip of incident wave, said azimuth and dip having different factors for controlling discrimination sharpness.