Rock Fracture Monitoring Based on High-Precision Microseismic Event Location Using 3D Multiscale Waveform Inversion

Figure 4

Location results of synthetic test event 7 obtained through multiscale waveform inversion and waveform inversion only based on a uniform fine grid. (a) Sliced plane of the 3D velocity model determined by the 18 sensors used for inversion in this test, and location results of waveform inversion in different-scale grids and uniform fine grid. (b) Locally enlarged map of iteration location results shown in (a). The yellow and red stars represent the initial location and iterative convergence process based on the coarse-grid FWI, respectively. The blue and cyan stars indicate the iteration processes of location based on the second-stage fine grid and single uniform fine-grid FWI, respectively. Moreover, the green and black stars denote the final location results and preset location of the test event, respectively. (c) Normalized waveform misfits during iterations. For multiscale waveform inversion, waveform misfit in each new stage is renormalized.

(a)

(b)

(c)