Reverse travel time imaging of microseismic location

ABSTRACT

The data sources used in microseismic locating include mainly the arrival time or waveform (wavefield value) in the microseismic record, and the algorithms used are mainly inversion or reverse time imaging. In terms of data source and algorithm, previously available methods generally fall into three categories: travel time inversion, waveform inversion, and reverse time imaging based on the wavefield. In this study, we propose a new reverse imaging method based on travel time. Starting with time invariance, we use the travel time of the back-propagated wavefield as a data source for imaging source location. We calculate the travel times from one receiver to all grid points directly rather than pick arrival times, and refer to this as the reverse travel time field (RTTF). The method of using the RTTFs of all receivers for imaging is called reverse travel time imaging (RTTI). RTTI images the whole research area and so overcomes the problem of a local minimum in travel time inversion. RTTI pre-prepares RTTF and there is no need to calculate travel time during imaging, which helps maintain the high computational efficiency as travel time inversion. The effectiveness, adaptability and resistance to some interfering factors in RTTI are tested using 2D acoustic numerical experiments.

KEYWORDS:

• Microseismic
• travel time
• imaging

Acknowledgments

Thanks to the funding of NSFC (Natural Science Foundation of China) (grant No. 41674124).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Funding was received from NSFC (Natural Science Foundation of China) (grant No. 41674124).