Picotti Stefano, Carcione José M, Santos Juan E, Gei Davide, Cavallini Fabio
National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy.
School of Earth Sciences and Engineering, Hohai University, Nanjing 211100, China.
J Acoust Soc Am. 2020 Oct;148(4):1978. doi: 10.1121/10.0002127.
P-wave conversion to slow diffusion (Biot) modes at mesoscopic (small-scale) inhomogeneities in porous media is believed to be the most important attenuation mechanisms at seismic frequencies. This study considers three periodic thin layers saturated with gas, oil, and water, respectively, a realistic scenario in hydrocarbon reservoirs, and perform finite-element numerical simulations to obtain the wave velocities and quality factors along the direction perpendicular to layering. The results are validated by comparison to the Norris-Cavallini analytical solution, constituting a cross-check for both theory and numerical simulations. The approach is not restricted to partial saturation but also applies to relevant properties in reservoir geophysics, such as porosity and permeability heterogeneities. This paper considers two cases, namely, the same rock skeleton and different fluids, and the same fluid and different dry-rock properties. Unlike the two-layer case (two fluids), the results show two relaxation peaks and the agreement between numerical and analytical solutions is excellent.
在地震频率下，多孔介质中细观（小尺度）不均匀性处P波转换为慢扩散（Biot）模式被认为是最重要的衰减机制。本研究考虑了分别充满气体、油和水的三个周期性薄层，这是烃类储层中的一个实际情况，并进行了有限元数值模拟，以获得沿垂直于分层方向的波速和品质因数。通过与诺里斯 - 卡瓦利尼解析解进行比较来验证结果，为理论和数值模拟提供了相互校验。该方法不仅限于部分饱和情况，还适用于储层地球物理学中的相关性质，如孔隙度和渗透率不均匀性。本文考虑了两种情况，即相同岩石骨架和不同流体，以及相同流体和不同干岩石性质。与双层情况（两种流体）不同，结果显示出两个弛豫峰，数值解与解析解之间的一致性非常好。
