189 7. Integrated seismic study Equation (7.9) has been used to compute the static Young’s modulus using logging data (dynamic modulus computed by equation (7.7)) and core data (static modulus obtained in the laboratory). The coefficients “a” and “b” are evaluated to obtain an optimum fit between the static modulus from core data with the predicted static modulus from logging data (Yven and Mari, 2018). Figure 7.19 (bottom left) shows the static Young’s moduli from the laboratory (blue crosses), the dynamic Young’s from logs (black crosses), and the predicted static Young’s moduli (red crosses). Figure 7.19 (right) shows the associated histograms. Figure 7.19 From dynamic to static moduli. Left: static Young’s moduli from laboratory (blue crosses), the dynamic Young’s moduli from logs (black crosses), and the predicted static Young’s moduli (red crosses). Right: histograms. Figures 7.20 to 7.22 show the results obtained on the seismic profiles 10EST10, IL405 and XL217 respectively. For each seismic line, we show the distribution of dynamic Young’s moduli in depth computed from the Vp, Vs and density distributions obtained by elastic inversion and depth conversion, the distribution of static Young’s moduli in depth given by equation (7.9), the static to dynamic ratio distribution in depth, and the histograms of the two sets of moduli. The Static to Dynamic Young’s modulus ratio varies between 0.49 to 0.58. The static to dynamic conversion has been carried out with cores from the Cox. In future, the relationship between static and dynamic will be analysed with other boreholes, per each geological unit.
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