Seismicity Induced by Hydraulic Fracturing in Shales: A Bedding Plane Slip Model. Issue 10 (7th October 2017)

• Record Type: Journal Article
• Authors: Staněk, František; Eisner, Leo
• Is Part Of: Journal of geophysical research. Volume 122:Issue 10(2017)
• Page Start: 7912
• Page End: 7926
• Publication Date: 2017-10-07
• Subjects: microseismicity -- source mechanisms -- shale -- hydraulic fracturing -- bedding plane slip; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1002/2017JB014213
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: Passive seismic monitoring of microseismic events induced in oil or gas reservoirs is known as microseismic monitoring. Microseismic monitoring is used to understand the process of hydraulic fracturing, which is a reservoir stimulation technique. We use a new geomechanical model with bedding plane slippage induced by hydraulic fractures within shale reservoirs to explain seismicity observed in a typical case study of hydraulic fracturing of a shale gas play in North America. Microseismic events propagating from the injection point are located at similar depths (within the uncertainty of their locations), and their source mechanisms are dominated by shear failure with both dip‐slip and strike‐slip senses of motion. The prevailing dip‐slip mechanisms have one nearly vertical nodal plane perpendicular to the minimum horizontal stress axis, while the other nodal plane is nearly horizontal. Such dip‐slip mechanisms can be explained by slippage along bedding planes activated by the aseismic opening of vertical hydraulic fractures. The model explains the observed prevailing orientation of the shear planes of the microseismic events, as well as the large difference between seismic and hydraulic energy. Key Points: The epicentres of microseismic events induced by hydraulic fracturing are aligned along the direction of the maximum principal stress The observed shear source mechanisms have opposite sense of slip on nearly identical fault planes The geomechanical model of bedding plane slip explains the observed mechanisms; the model is suitable for shales with weak bedding planes