--> Rupture Behavior of Induced-Triggered Seismicity Observed During Hydraulic Fracture Stimulations
[First Hit]

AAPG Annual Convention and Exhibition

Datapages, Inc.Print this page

Rupture Behavior of Previous HitInducedNext Hit-Triggered Previous HitSeismicityNext Hit Observed During Hydraulic Fracture Stimulations

Abstract

The occurences of larger magnitude events (M>0) associated with hydraulic fracture stimulations may pose concerns from both a public perception and an engineering perspective. Through the use of a unique hybrid seismic recording network, we investigate the fracture characteristics of these Previous HitinducedNext Hit-triggered events by examining both the dynamics of the sub-fracture failures during the rupture process and growth of the overall fracture from initiation to rupture arrest. This was achieved by incorporating both high frequency recordings utilizing 15 Hz omni-directional geophones situated in close proximity to the reservoir and thereby the point of rupture initiation and near surface low frequency recordings obtained using force balance accelerometers (0.1Hz) and geophones (4.5Hz) that allowed for the investigation of overall rupture characteristics. By utilizing such a recording network, we were able to examine different aspects of the rupture processes, including the role of asperities, roughness, the role of fluids and the failure mechanisms (shearing versus tensile dominance of behavior) associated with these Previous HitinducedNext Hit-triggred events. Our initial results suggests that overall shearing is the dominant mode of failure, whereas the rupture characteristics of the sub-fracture failures are more complex than a simple shearing process and include a strong tensile component of failure. Our measurements of rupture complexity, seismic efficiency, rupture velocity and estimates of stress release further support the idea that the sub-fractures are characterized by the failure of multiple asperities that exhibit self-similar behaviour within themselves. These observations are part of ongoing investigations that may allow for the assessment of conditions under which Previous HitinducedNext Hit-triggered failures may occur. By comparing events originating within the reservoir with those occurring outside the injection volume during the stimulation we also will assess whether the role of fluids can be identified and if the observed signatures uniquely characterize Previous HitinducedTop versus triggered behavior thereby allowing for the distinction between event types.