f Monitoring the Widt of Hydraulic Fractures with Ultrasonic Measurements

During hydraulic fracturing experiments in the laboratory the opening of hydraulic fractures is monitored with ultrasonic transducers. The experiment closely resembles seismic monitoring surveys in the field [MEADOWS AND WINTERSTEIN 1994, WILLS ET AL. 1942]. The extraction of information out of these experiments is critically dependent on the understanding of the elastodynamic behaviour of the thin fluid filled fractures. The laboratory experiments provide useful information on what determines the seismic visibility of these fractures, both for compressional and shear waves. The role of the fracture thickness or width on the elastodynamic response and a new method for monitoring fracture opening is investigated.