Estimation of compressional seismic wave attenuation of carbonate rocks in Abu Dhabi, United Arab Emirates
Estimation of compressional seismic wave attenuation of carbonate rocks in Abu Dhabi, United Arab Emirates
复制标题
阿拉伯联合酋长国阿布扎比碳酸盐岩压缩地震波衰减的估计
DOI：
10.1016/j.crte.2014.05.002
复制
发表时间：
2014
影响因子：
1.4
通讯作者：
Asam Farid
中科院分区：
文献类型：
--
作者：
F. Bouchaala;Mohammed Y. Ali;Asam Farid
阿拉伯联合酋长国阿布扎比的地下地质主要由碳酸盐岩组成。已知这样的介质是高度异质的。很少有研究试图估计碳酸盐岩中的衰减。阿布扎比没有公布衰减概况。这项研究提供了第一个地震波衰减剖面在阿布扎比使用密集阵列的VSP数据。我们估计三个衰减配置文件：表观，散射，和固有的衰减。利用振幅衰减和频谱比方法计算了表观衰减剖面。利用广义反射-透射矩阵正演模型估计了散射衰减剖面。它通常是由声波测井估计的，但为了与视衰减更一致，本文成功地从VSP数据估计它。我们从表观衰减中减去散射衰减来推导出本征衰减。研究结果表明，与主要基于碎屑岩的已发表研究相比，散射衰减是显着的。高散射衰减可达0.02。这可以用碳酸盐岩的强烈非均质性来解释。这项研究表明，Simsima和罗斯组有相当大的散射和内在的衰减。这些地层被认为是阿布扎比的含水层;因此，我们认为这种高固有衰减区是由于这些地层中的异质性和流体。Umm-Er-Radhuma地层是一个更均匀的地层，含水层潜力有限。因此，Umm-Er-Radhuma地层的散射和固有衰减较低。
The subsurface geology of Abu Dhabi in the United Arab Emirates is primarily composed of carbonate rocks. Such media are known to be highly heterogeneous. Very few studies have attempted to estimate attenuation in carbonate rocks. In Abu Dhabi no attenuation profile has been published. This study provides the first seismic wave attenuation profiles in Abu Dhabi using dense array of VSP data. We estimated three attenuation profiles: the apparent, the scattering, and the intrinsic attenuations. The apparent attenuation profile was computed using amplitude decay and spectral-ratio methods. The scattering attenuation profile was estimated using a generalized reflection–transmission matrix forward model. It is usually estimated from the sonic log, but to be more consistent with the apparent attenuation, we succeeded in this paper to estimate it from the VSP data. We subtracted the scattering attenuation from the apparent attenuation to deduce the intrinsic attenuation. The results of the study indicate that the scattering attenuation is significant compared to the published studies that are mainly based on clastic rocks. The high scattering attenuation can reach up to 0.02. It can be explained by the strong heterogeneity of the carbonate rocks. This study demonstrates that the Simsima and Rus Formations have considerable scattering and intrinsic attenuations. These formations are considered aquifers in Abu Dhabi; we therefore interpreted this high intrinsic attenuation zones to be due to the heterogeneity and to the fluids contained in these formations. The Umm-Er-Radhuma Formation is a more homogenous formation with limited aquifer potential. Hence, scattering and intrinsic attenuations of the Umm-Er-Radhuma Formation are low.