Liu, XuejianZhu, TieyuanAjo-Franklin, Jonathan2023-03-102023-03-102023Liu, Xuejian, Zhu, Tieyuan and Ajo-Franklin, Jonathan. "Understanding Subsurface Fracture Evolution Dynamics Using Time-Lapse Full Waveform Inversion of Continuous Active-Source Seismic Monitoring Data." <i>Geophysical Research Letters,</i> 50, no. 4 (2023) Wiley: https://doi.org/10.1029/2022GL101739.https://hdl.handle.net/1911/114491Predicting the behavior, geometry, and flow properties of subsurface fractures remains a challenging problem. Seismic models that can characterize fractures usually suffer from low spatiotemporal resolution. Here, we develop a correlative double-difference time-lapse full waveform inversion of continuous active source seismic monitoring data for determining high-spatiotemporal-resolution time-lapse Vp models of in-situ fracture evolution at a shallow contamination site in Wyoming, USA. Assisted by rock physics modeling, we find that (a) rapidly increasing pore pressure initializes and grows the fracture, increasing the porosity slightly (from ∼13.7% to ∼14.6%) in the tight clay formation, thus decreasing Vp (∼50 m/s); (b) the fluid injection continues decreasing Vp, likely through the introduction of gas bubbles in the injectate; and (c) final Vp reductions reach over ∼150 m/s due to a posited ∼4.5% gas saturation. Our results demonstrate that high-resolution Vp changes are indicative of mechanical and fluid changes within the fracture zone during hydrofracturing.engThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.Journal article2023-Liuhttps://doi.org/10.1029/2022GL101739