Non-linear Calibration of Complex Velocity Models in Microseismic Jobs
T. Bardainne and E. Gaucher
Event name: Second EAGE Passive Seismic Workshop - Exploration and Monitoring Applications 2009
Session: Reservoir Monitoring I
Publication date: 22 March 2009
Info: Extended abstract, PDF ( 379.29Kb )
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The calibration of the velocity model in microseismic jobs is critical to achieve statistically reliable microseismic locations. Indeed, the lack of knowledge of the wave propagation medium is the main source of location inaccuracy. This paper presents a non-linear calibration method of velocity models for passive, microseismic surveys. This method analyzes multiple time and polarization arrivals and uses a non-linear inversion, simulated annealing algorithm, which prevents the velocity solution from converging to a local minimum, to minimize the residuals and the location error measurements. This method calibrates complex velocity models which can be described, by velocities (P&S), velocity gradients, dip of layers or 3d surface layers. We present an example that demonstrates a significant decrease in location errors of microseisms as compared to typical methods.