Microseismic Monitoring

Recent Advances and Challenges of Waveform‐Based Seismic Location Methods at Multiple Scales

“…Microseismic monitoring is a passive seismic technique enabling analysis of microearthquakes, which are used to map fracture reactivation/creations, and fluid movements. Microseismic monitoring is used in mining, fluid injection and extraction, hydraulic fracturing, and other geoengineering operations (Grechka & Heigel, ; Maxwell, ; Shapiro, ). Passive seismic monitoring has been applied in the mining industry and geothermal reservoirs for more than 60 years (Gibowicz & Kijko, ; Obert & Duvall, ).…”

“…Seismic source location methods can be divided into three broad categories based on the role of the velocity model (Grechka & Heigel, ): (i) Geiger‐type inversion with a priori fixed velocities, (ii) tomographic techniques that iteratively update the velocity structure in the location process, and (iii) relative location methods that can position events relative to each other and relative to the selected velocity distribution. Due to the lack of sufficient constraints and related significant computational demands, the challenge of locating and characterizing an unknown source in a largely unknown medium is commonly divided into isolated subproblems.…”

“…While this separate treatment of source and medium properties led to significant success and can still be considered common practice, there also exist techniques that aim at a joint estimation of the source location and the velocity distribution, thereby accounting for the coupled nature of the full inverse problem (cf. Grechka & Heigel, ). A recent attempt at confronting the practical challenges of the underdetermined joint inversion is based on an analysis of the local wavefield coherence (B. Schwarz et al, ; Diekmann et al, ).…”

“…The velocity model can be improved by taking advantage of both active and passive seismic data. Both the traveltime and waveform amplitude of recorded data contain information on velocity structure and can be utilized to constrain the inversion either tomographically or through migration principles (Grechka & Heigel, ). The joint estimation of both source characteristics and the seismic velocity distribution is expected to confront model uncertainties in a more effective manner (see sections and ).…”

“…Though only several exploratory studies have been conducted, passive seismic reservoir imaging bears great potential for providing new opportunities in reservoir characterization (Grechka & Heigel, ; B. Schwarz et al, ). However, there are still several technical issues that need further study, for example, the influence of irregular spatial distribution of sources and receivers and reliable wavefield separation from low‐SNR passive seismic data (Grechka & Heigel, ).…”