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Physical modeling, using ultrasonic sources and receivers over scaled exploration structures, plays a useful role in wave propagation and elastic property investigations. This paper explores the anisotropic response of novel fractured glass blocks created with a laser-etching technique. We compare transmitted and reflected signals for P-and Swaves from fractured and unfractured zones in a suite of ultrasonic experiments. The unaltered glass velocities are 5801 m/s and 3448 m/s for P and S waves, respectively, with fractured zones showing a small decrease (about 1%). Signals propagating through the fractured zone have decreased amplitudes and increased coda signatures. Reflection surveys (zero-offset and variable polarization and offset gathers) record significant scatter from the fractured zones. The glass specimens with laser-etched fractures display a rich anisotropic response.

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Many regions of subsurface interest are, or will be, fractured. Seismically characterizing these zones is a complicated but essential task for resource development. Physical modeling, using ultrasonic sources and receivers over scaled exploration targets, can play a useful role as an analog for reservoir imaging and assessment. We explored the anisotropic response of glass blocks containing internal fractures created by a novel laser-etching technique. We compared transmitted and reflected signals for P- and S-waves from fractured and unfractured zones in a suite of ultrasonic (1–5 MHz) experiments. The unaltered glass velocities have averages of [Formula: see text] and [Formula: see text] for P- and S-waves, respectively (giving [Formula: see text]). The unfractured glass has a very high quality (Q) factor of over 500 for P-waves and S-waves. The fractured zones have a small (up to 1.5%) velocity decrease. Signals propagating through the fractured zone have diminished amplitudes and increased coda signatures. Reflection surveys (zero-offset and with variable polarizations) record significant scatter from the fractured zones. The fracture-scattered energy can be migrated to provide a sharper image. The glass specimens with laser-etched fractures display a rich anisotropic response, which can help inform field-scale imaging.

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Studies of orthorhombic anisotropy are becoming progressively essential, especially as many sedimentary rocks are considered to have orthorhombic symmetry. To study the effect of stress in a layered orthorhombic medium, a physical modeling study using intrinsically orthorhombic phenolic boards was conducted. The experiment was designed to simulate sedimentary reservoir rocks deposited in layers with inherent orthotropic symmetry and under the influence of stress due to overlying sediments. The study also explores which geologic phenomena dominate the contortion of anisotropy under different stress tenure. The phenolic boards were coupled together with the help of a pressure device and uniaxial stress was gradually increased while time arrival and velocity measurements were repeated. Results show maximum increase in compressional and shear wave velocities ranging from 4% to 10% in different directions as a function of increasing uniaxial stress. P and S wave dependent stiffness coefficients generally increased with stress. Anisotropic parameters (extension of Thomsen's parameters for orthorhombic symmetry) generally diminished or remained constant with increasing pressure and changes ranged from 0% to 33%. We observed anisotropic behavior a priori to both orthorhombic and VTI symmetries in different principal axes of the model. Polar anisotropy behavior is due primarily to layering or stratification and tends to increase with pressure. Certain anisotropic parameters however unveil inherent orthotropic symmetry of the composite model.