Seismic Waves as a Tool To Interpret Complex Fractures

Rock fractures have a crucial role in geomechanics affecting rock behavior. Seismic waveforms carry information about the medium through which it has propagated. Extracting information from waveforms can lead to conclusions about the heterogeneity and anisotropy of the medium and an estimation of density and mechanical stiffness of fractures. The stress field in a fractured medium is also important as it controls the closure of the fracture and hence the fracture stiffness. Using seismic waveforms, we can make indirect conclusions about the stress state of the medium. Models and experiments in a medium with discrete parallel fractures have led to confidence that the models can accurately reproduce wave interaction with fractures. But what about waveforms for waves propagating through a more complex fracture network? In this work we use a DFN tool to create a fracture network and pass seismic waves through the medium recording velocity waveforms. From this we reach conclusions on how the fracture networks are affecting the seismic waveforms with implications for real-world problems. We extend this work to include the local stress field which alters fracture stiffness along fractures establishing how these changes affect seismic waveforms compared to the initial uniform stress model.