Title | Acoustic Emission Characteristics of Shale |
Publication Type | Conference Proceedings |
Year of Conference | 2015 |
Authors | Moradian, Z, Li, QB, Goncalvez da Silva, B, Germaine, JT, Einstein, H |
Conference Name | International Symposium on Rock Mechanics Congress |
Keywords | Acoustic emission, Anisotropy, Attenuation, Frequency domain, Shale, Source Location, Time domain, Waveform |
Abstract | Shale gas and oil production has grown rapidly in recent years, and consequently there are increasing demands to
understand the mechanical and microseismic properties of shale. Acoustic emission (AE) monitoring provides
useful information on the fracture mechanisms of shale rocks, and provides a basis for interpreting field seismic
observations. While there have been attempts for microseismic monitoring of conventional hydrocarbon reservoirs,
shale presents a large number of issues that require further investigation. For this purpose, experiments were
conducted to understand the characteristics of the AE waveforms propagated through Opalinus shale rock in the
time and frequency domains. Frequency range, arrival time, first arrival amplitude and other parameters such as
counts, duration and energy of the waves generated from artificial and natural sources in the shale specimens were
detected and compared with AE characteristics of granite, a brittle rock that has been extensively investigated. The
experimental tests showed that there are some important factors that influence the analyses and interpretations of
seismic surveys and microseismic monitoring of shale compared to granite. One of these factors is the anisotropic
behavior of shale that causes the wave to propagate with different velocities in different directions. Also bedding
planes and micro-discontinuities in the shale cause attenuation of the waves. Thus the AE waveforms that arrive at
the sensor are a distorted and attenuated versions of the source waveform. |