Development of a Neutron Diffraction Based Experimental Capability for Investigating Hydraulic Fractures for EGS-like Conditions

Understanding the relationship between stress state, strain state and fracture initiation and propagation is critical to the improvement of fracture simulation capability if it is to be used as a tool for guiding hydraulic fracturing operations. The development of fracture prediction tools is especially critical for geothermal applications such as EGS because the opportunities to build understanding empirically will be limited due to the high costs associated with field trials. There is a significant body of experimental work associated with hydraulic fracture investigation, but past efforts are typically hampered by an inability to accurately and comprehensively measure strains within the sample mass near critical regions of interest.

This work aims to develop non-destructive neutron diffraction based strain measurement techniques that can be used to interrogate the internal volume of geological specimens subjected to tri-axial stress states resembling geothermal application conditions. Demonstrating the ability of the technique to generate useful quantitative data is the primary focus at this stage of the effort. Details of the experimental setup and diffraction technique will be presented in this communication, including the description of a custom designed high-pressure, neutron scattering