Borehole logging results, P-wave velocities (V_P(0), absolute values of velocity gradient along borehole parallel trajectories, and 2-D seismic velocity distribution from tomographic inversion. TVD: true vertical depth within the experimental plane. The depth interval identified as an anomaly in the visual analysis of the BDR-D2 core (10.1–11.1 m WD) is indicated by horizontal lines. The suggested positions of the diffusion borehole and injection interval in the borehole are shown as a thick vertical line and rectangle with white filling, respectively. The injection interval would be located between approximately 9 and 10 m depth in the experimental plane, corresponding to 9.5 and 10.6 m WD in the exploratory wells, due to their inclination within the experimental plane.