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首页> 外文期刊>Archives of Applied Science Research >Seismic wave attenuation characteristics of tertiary sediments in niger delta field
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Seismic wave attenuation characteristics of tertiary sediments in niger delta field

机译：尼日尔三角洲地区第三纪沉积物的地震波衰减特征

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Seismic attenuation analysis is important for several reasons, including aiding seismic risk evaluation. Quality factors and attenuation coefficients have been estimated for an X-field in the Niger Delta, whose near surface sediments has remained largely uncharacterized. Using surface waves extracted from seismic data acquired by conventional reflection methodology and employing the quality factor versus offset (QVO) technique of attenuation analysis, reliable attenuation coefficient and quality factor distributions for the field covering about 25 km2 has been generated. The value of quality factors obtained indicate that the near surface sediments are low in attenuation to surface waves, being largely unconsolidated. The value of quality factors ranges from 20 to 80, corresponding to attenuation coefficients of between 0.0006 to 0.002 m-1. The estimated attenuation factors in this study tend to have some form of dependence on the thickness of unconsolidated sediments. In most parts of the field, especially in the northern parts it is observed that areas with thin unconsolidated sediments thickness have higher attenuation factors than areas with thick unconsolidated sediments. These results correlates well with those of previous studies in similar geologic settings. Generally, the field is low in attenuation with high quality factors and therefore, susceptible to seismic hazards due to surface wave amplifications. This however, will enhance stress levels and distribution in the near surface sediments which will affect the stability of civil structures. Therefore, appropriate engineering standards must be adopted to ensure stability of engineering structures in the field.
机译：地震衰减分析之所以重要，有几个原因，包括协助地震风险评估。已对尼日尔三角洲X场的质量因子和衰减系数进行了估算，该区域的近地表沉积物基本上没有特征。使用从通过常规反射方法获取的地震数据中提取的表面波，并采用衰减分析的品质因数与偏移量（QVO）技术，已生成了覆盖约25 km2的可靠的衰减系数和品质因数分布。所获得的品质因数的值表明，近地表沉积物对地表波的衰减低，基本上没有固结。质量因子的值在20到80的范围内，对应于0.0006到0.002 m-1之间的衰减系数。在这项研究中估计的衰减因子倾向于对未固结沉积物的厚度有某种形式的依赖性。在该油田的大部分地区，特别是在北部地区，观察到未固结沉积物厚度薄的区域比未固结沉积物厚的区域具有更高的衰减因子。这些结果与先前在类似地质环境中的研究结果具有很好的相关性。通常，该场的衰减系数低，品质因数高，因此容易受到由于表面波放大而引起的地震危险的影响。但是，这将增加应力水平和近地表沉积物中的分布，这将影响土木结构的稳定性。因此，必须采用适当的工程标准来确保现场工程结构的稳定性。

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