Knowledge of the S-wave velocity ($V_{\mathrm{S}}$) and density ($\rho$) is essential for oil and gas reservoir detection and characterization. However, reliable recovery of both parameters, especially density, from the reflected PP-wave data is a difficult issue because this inverse problem is highly ill-conditioned. The reflected SV-SV wave is easier to process than the PS-wave, and it can provide better estimates of $V_{\mathrm{S}}$ and $\rho$ than the PP-wave because it is more sensitive to these parameters than the PP-wave. I have developed a simultaneous inversion for $V_{\mathrm{S}}$ and $\rho$ based on a modified approximation of the SV-SV wave reflection coefficient. The modified equation includes only two parameters (natural logarithms of $V_{\mathrm{S}}$ and $\rho$) to be inverted, and it has high accuracy even at large incident angles and for strong impedance contrasts. I find that simultaneous inversion based on the modified approximation is well-posed when using data of small-to-moderate incident angle (20^o–30^o) and that the misfit function can be easily regularized. The new simultaneous inversion method is applied to an SV-SV wave prestack data set acquired from a 2D nine-component survey. The field data example demonstrates that the new method can recover stable and high-resolution density and S-wave velocity information, which can be used to investigate rock mineral composition, porosity, and fluid content.

中文翻译：

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SV-SV波同时反演S波的速度和密度

了解S波速度（$V_{\mathrm{小号}}$）和密度（$\rho$）对于油气储层的检测和表征至关重要。然而，从反射的PP波数据中可靠地恢复两个参数，尤其是密度，是一个困难的问题，因为该反问题非常严重。反射的SV-SV波比PS波更易于处理，并且可以更好地估计$V_{\mathrm{小号}}$ 和 $\rho$与PP波相比，因为它对这些参数比PP波更敏感。我已经为$V_{\mathrm{小号}}$ 和 $\rho$基于SV-SV波反射系数的修正近似值。修改后的方程式仅包含两个参数（$V_{\mathrm{小号}}$ 和 $\rho$）进行反转，即使在大入射角下也具有很高的精度，并且具有很强的阻抗对比。我发现，当使用小到中等入射角（20 ^o –30 ^o）的数据时，基于修正近似值的同时反演具有很好的条件，并且失配函数可以很容易地进行正则化。新的同时反演方法应用于从二维九分量测量中获取的SV-SV波叠前数据集。现场数据示例表明，该新方法可以恢复稳定且高分辨率的密度和S波速度信息，可用于研究岩石矿物成分，孔隙度和流体含量。