Fractures are mechanical breaks in rock and they are a very common feature within the Earth’s crust. They originate in response to lithostatic, tectonic and thermal stress and their size can occur at a variety of scales, ranging from microscopic to continental (hundreds of kilometres). They play an important role in mechanical and hydraulic behaviour of rock masses being responsible in providing pathways for fluid flow and its transportation in the subsurface as well as affecting the stability of engineered structures and excavations (e.g. mines, geological disposal facilities).
Thus, an understanding of the physical properties of fracture zones, location, orientation, and geometry, is of primary importance in the comprehension of geo-resources (oil and gas, groundwater, geothermal reservoirs) and geo-hazards (rock-bursts in mines, landslides,earthquakes). Seismic waves can be an efficient tool for non-invasive detection and characterisation of physical properties of fractures. This is due to the fact that seismic waves propagating through fractured rock experience a change in wave velocities (seismic anisotropy), amplitude and frequency (wave scattering and phase shifting phenomena) as a function of fracture properties such as stiffness, size, orientation, fracture spacing, infill, and density (Crampin, 1981; Schoenberg & Sayers, 1995; Rüger, 1998; Tsvankin & Grechka, 2011).
There is a variety of techniques which are able to extract some fracture properties from seismic data. Most of them deal with the characterisation of seismic anisotropy in order to estimate (as an inverse process) physical properties of interest such as fracture density and orientation (Liu, 2013). However, the effects of a fracture set are usually averaged when attempting to understand the impacts on seismic waves.
To circumvent these limitations, we propose a new methodology which combines realistic wave propagation modelling in fractured media - WAVE (Hildyard, 2007) - with the Full Waveform Inversion technique which has shown a robustness in estimating physical properties of the subsurface from observed seismic data (Virieux & Operto, 2009; Warner et al., 2013).
- MSc (Hons) Exploration and Applied Geophysics, University of Pisa (Italy)
- BSc Physics, University of Pisa (Italy)
Research groups and institutes
- Applied Geophysics
- Institute of Applied Geoscience
- Institute of Geophysics and Tectonics