Microseismic Source Location Estimation Using Reverse Double-Difference Time Imaging

To locate microseismic sources, the reverse double-difference time imaging method is proposed in this paper. The traditional time-reversal imaging method requires an accurate velocity model. To reduce the influence of the velocity model errors, this method uses the reverse travel time difference from adjacent receivers to each grid point of the velocity model and the arrival time difference of the microseismic event for imaging. We propose two imaging conditions for single source imaging and multi-source imaging to obtain high-resolution images of the sources. These imaging conditions are robust and can eliminate the error caused by outliers in the reverse double-difference time. The k-means clustering algorithm is used to optimize positioning results. Numerical experiments for source location estimation demonstrate that the reverse double-difference time imaging method is stable and reliable, and can locate multiple seismic sources with high-precision when the velocity model has errors. Some factors affecting the accuracy of source location estimation in the reverse double-difference time imaging are tested using 2D numerical experiments.