Close Observation of Hydraulic Fracturing at EGS Collab Experiment 1: Fracture Trajectory, Microseismic Interpretations, and the Role of Natural Fractures

Despite the wide application of hydraulic fracturing in enhanced geothermal system (EGS) development and unconventional hydrocarbon production, our understanding many factors affecting propagation fractures has relied on circumstantial evidence. This is partly due to scarcity direct observations subsurface. The EGS Collab project attempts address these issues context research by performing intermediate-scale (?10 m) stimulation experiments a thoroughly characterized heavily instrumented underground testbed. paper analyzes data collected from first suite tests this testbed, consisting seven episodes. High-quality microseismic delineate five planar features very clearly. Combining fracture-wellbore intersection distributed temperature sensing (DTS) visual an open-hole well, as well prior in-situ stress measurements, we conclude with high certainty that four larger planes were fractures. growth was temporarily halted prominent, open natural fracture testbed but they eventually crossed slightly reoriented under continued stimulation. Mineral-filled (i.e., healed) fractures, though prevalent did not have perceivable effects propagation. high-quality, mutually corroborating sets allowed conclusions be drawn confidence attests advantage subsurface research.