Riazi, NaimehEaton, David W.Aklilu, AlemayehuPoulin, Andrew2020-10-212020-10-212020-08-10http://hdl.handle.net/1880/112701https://doi.org/10.11575/PRISM/46065Characterization of induced seismicity and associated microseismicity is an important challenge for enhanced oil recovery and development of tight hydrocarbon reservoirs. In particular, accurately correlating hypocenters of induced events to stratigraphic layers plays an important role in understanding the mechanisms of fault activation. Existing methods for estimating focal depth, however, are prone to a high degree of uncertainty. A comprehensive analysis of inferred focal depths is applied to induced events that occurred during completions of horizontal wells targeting the Montney Formation in British Columbia, Canada. Our workflow includes a probabilistic, nonlinear global-search algorithm (NonLinLoc), a hierarchical clustering algorithm for relative relocation (GrowClust) and depth refinement using the recently developed focal-time method. The focal-time method leverages stratigraphic correlations between P-P and P-S reflections to eliminate the need for an explicit velocity model developed specifically for hypocenter depth estimation. We show that this approach is robust in the presence of noisy picks and location errors from epicenters obtained using a global-search algorithm, but it is limited to areas where multicomponent 3-D seismic data are available. A novel method to determine statics corrections is developed here, to ensure that both passive seismic observations and 3-D seismic data share a common datum in areas of moderate to high topography. Our results highlight the importance of transverse faults, which appear to provide permeable pathways for activation of other faults at distances of up to 2 km from hydraulic fracturing operations.engUnless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. This is the authors accepted version of a paper published in the journal Geophysics. Access to the version of record is via the citation below. Use of this version is subject to the terms of the publisher, SEG Library. Naimeh Riazi, David W. Eaton, Alemayehu Aklilu, and Andrew Poulin, (), "Application of Focal-Time Analysis for Improved Induced Seismicity Depth Control: A Case Study from the Montney Formation, British Columbia, Canada," GEOPHYSICS 0: 1-70. https://doi.org/10.1190/geo2019-0833.1induced seismicitymicroseismichydraulic fracturingstaticsjournal articlehttp://dx.doi.org/10.1190/geo2019-0833.1