The Model Fracture: An Experimental Study of Fluid-Driven Fractures and Resulting Backflow Observed in a Hydraulic Fracture

Abstract

We design a two-crack experiment to study the effects of natural faults on hydraulic fractures. Expanding on studies of a crack in a single layered elastic matrix, we inject liquid into a multi-layered elastic matrix. We observe crack growth due to the propagation of the fluid as well as crack closure following the release of the injection pressure following the completion of the fracture process. We use two separate methods to quantify our results. First, we utilize a photometric process based on the reflected light intensity of a fluorescent dye. Secondly, we utilize particle-image velocimetry programming to track movement of seeded fluorescent particles excited by a high-intensity laser sheet. Crack radius, thickness, volume, and displacement vectors within the gelatin material of the system can be quantified. We use trends in these values to mathematically model the system and explain them using scaling laws.