Experimental Observations of the Effects of Fracture Scale on Elastic Wave Velocity and Anisotropy
P.B. Ding, B.R. Di, J.X. Wei and X.Y. Li
Event name: 76th EAGE Conference and Exhibition 2014
Session: Rock Physics - Case Studies and Stress Dependencies
Publication date: 16 June 2014
Info: Extended abstract, PDF ( 753.93Kb )
Price: € 20
We use a new construction method to build synthetic sandstone samples with controlled fracture parameters and mineral composition, porous morphology, and cementation more similar to natural rocks. Four samples are built for experimental measurements; one is unfractured while the other three have different fracture diameters but the same fracture density. The fracture density in the fractured samples are 4.8%, 4.86% and 4.8% with fracture scales 2 mm, 3 mm, and 4 mm respectively; the fracture thicknesses in the fractured samples are all about 0.06 mm. Four samples are tested with ultrasonic devices, and both P and S wave velocities in different propagation directions are measured with 0.5 MHz transducers. The measurements show that the P wave and S wave velocity is substantially affected by the fracture scale. The P and S wave anisotropy of samples with smaller scale fractures is significantly higher than the samples with larger scale fractures.