Relative location of microseismicity

Abstract

Applying the two-point paraxial ray tracing, we develop a technique for relative location of microseismic events. Our technique assumes the availability of a perforation shot or an already located microseismic event, termed the master, for which the paraxial ray tracing has been performed. The ray-tracing output for the master makes it possible to compute the relative locations of adjacent microseismic events, as many as a data set contains, with an efficient algorithm that requires no additional ray tracing and reduces to solving a series of simple, low-dimensional and well-behaved optimization problems. The relative event-location approach discussed in our paper is especially well suited for surface microseismic monitoring because the high accuracy of the paraxial ray approximation in the directions orthogonal to the reference rays, typically spanning the stimulated horizons for surface microseismic geometries, ensures the calculation of precise event hypocenters at appreciable distances from the master. Also, since our computations operate with differences of the recorded times of microseismic events rather than with the times themselves, inaccuracies in static corrections for surface receiver stations are largely eliminated. We test the relative location technique on synthetic and field microseismic data to demonstrate its accuracy, computational efficiency, and insensitivity to velocity errors.

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

“…They are also known as picking‐ or ray‐based methods (Z. Li & van der Baan, ; Pesicek et al, ). Many modifications have been introduced to improve the performance of the traveltime‐based methods, most of which lie in the construction of misfit function and inversion strategies, such as joint hypocenter location method (e.g., Douglas, ; Pujol, ), relative location method (e.g., Fitch, ; Grechka et al, ; Spence, ), plain grid search (e.g., Eisner et al, ), master‐station or station‐pair double difference method (e.g., Font et al, ; Zhang et al, ; Zhou, ), joint location and velocity inversion (e.g., Block et al, ; Jansky et al, ; Z. Zhang et al, ; Diekmann et al, ), double difference relocation method (Waldhauser & Ellsworth, ; H. Zhang & Thurber, ; Hauksson & Shearer, ; Waldhauser & Schaff, ; Kwiatek et al, ), and cluster‐based relocation methods (G. Lin et al, ; P. Shearer et al, ; Matoza et al, ; Trugman & Shearer, ).…”

“…Li & van der Baan, 2016;Pesicek et al, 2014). Many modifications have been introduced to improve the performance of the traveltime-based methods, most of which lie in the construction of misfit function and inversion strategies, such as joint hypocenter location method (e.g., Douglas, 1967;Pujol, 1992), relative location method (e.g., Fitch, 1975;Grechka et al, 2015;Spence, 1980), plain grid search (e.g., , masterstation or station-pair double difference method (e.g., Font et al, 2004;Zhang et al, 2010;Zhou, 1994), joint location and velocity inversion (e.g., Block et al, 1994;Jansky et al, 2010;Z. Zhang et al, 2017;Diekmann et al, 2019), double difference relocation method (Waldhauser & Ellsworth, 2000; H. Zhang Figure 2.…”

Anisotropic eikonal solution using physics-informed neural networks

“…Fast and accurate traveltime computation is essential to the success of many seismic applications including statics and moveout correction (Lawton, 1989), traveltime tomography (Taillandier et al, 2009), microseismic source localization (Grechka et al, 2015), and ray-based migration (Lambaré et al, 2003). Many of the actively explored regions in the world exhibit seismic anisotropy, for example, the North Sea, the Canadian foothills, and offshore West Africa.…”

Automatic microseismic stacking location with a multi-cross-correlation imaging condition

“…During the monitoring, parameters of detected microseismic events are utilized to delineate the distribution and shape of fracture network. For the hydraulic stimulation, these characteristics can be used to interpret fracturing efficiency as well as adjust treatment design and evaluate the stimulated reservoir volume better (Li et al, 2014;Grechka et al, 2015).…”