Laboratory hydraulic fracturing visualization experiments on transparent rock analogues containing preexisting fractures are presented. Soda-lime glass cubes (10 cm×10 cm×10 cm) containing pre-existing, partially open fracture networks are subjected to true-triaxal stress state while viscous fluid is injected through a small (~3 mm diameter) analogue borehole to induce fractures in the sample. The preexisting fractures consist of either laser-etched microcracks or thermal-shock-induced fractures which are partially healed by re-heating of the glass. Initiation and propagation of the hydraulic fractures are monitored and recorded visually via webcams and acoustically using acoustic emissions. A series of experiments conducted with different fluid injection rates of the fracturing fluid show that the injection rate can have a significant impact on the interactions between hydraulic fractures and pre-existing fractures—fast injection results in less interactions—, affecting the overall geometry of the resulting hydraulic fracture network. Experiments involving time-varying (frequency-modulated) injection rate are also conducted, yielding different complexity and characteristics of the hydraulic fracture network.
Laboratory Visualization of Hydraulic Fracture Propagation Induced by Variable-Rate Fluid Injection Within Analogue Rock Samples Containing Preexisting Fractures
- Share Icon Share
- Search Site
Nakagawa, S. "Laboratory Visualization of Hydraulic Fracture Propagation Induced by Variable-Rate Fluid Injection Within Analogue Rock Samples Containing Preexisting Fractures." Paper presented at the 51st U.S. Rock Mechanics/Geomechanics Symposium, San Francisco, California, USA, June 2017.
Download citation file: