| 黏弹性和速度各向异性对薄层反射的影响 |
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| 引用本文： | 陈本池,王超,陈常兴,时磊.黏弹性和速度各向异性对薄层反射的影响[J].煤田地质与勘探,2019,47(5):186-192. |
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| 作者姓名： | 陈本池 王超 陈常兴 时磊 |
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| 作者单位： | 中国石油化工股份有限公司科技部油田处;中国地质大学(北京)地球物理与信息技术学院地质过程与矿产资源国家重点实验室MWMC研究组;淮南矿业(集团)有限责任公司;中国石油化工股份有限公司石油勘探开发研究院 |
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| 基金项目： | 国家自然科学基金项目（41604119，41425017）；中石化研发项目（P18070-5）；国家科技重大专项任务（2016ZX05002-005-008） |
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| 摘 要： | 煤层具有强波阻抗差、低阻抗的特性，对地震勘探来说是一种典型的薄层。因为其黏弹性和速度各向异性导致薄层反射波场异常，为了定量分析黏弹性和速度各向异性对薄层地震反射的影响，针对强波阻抗差薄层模型，基于波动方程数值模拟方法，正演得到弹性速度各向同性、黏弹性速度各向同性及黏弹性速度各向异性的地震波场，并对比分析了3种模型的弹性波地震反射特征。研究结果表明:黏弹性对薄层的反射产生不可忽略的影响，会明显降低薄层弹性波的反射振幅，但黏弹性速度各向同性与各向异性对薄层的弹性波反射影响差异不大。相比于弹性各向同性情况，黏弹性会引起反射纵波（PP波）瞬时频率最大可达8%的改变量，而对转换横波（PS波）仅有3%的改变量，可以忽略不计。上述研究为利用构造煤品质因子极低的特征来预测构造煤提供了可能。
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| 关 键 词： | 薄层 煤层 黏弹性 速度各向异性 AVO属性 |
| 收稿时间： | 2018-12-11 |
The effect of viscoelasticity and velocity anisotropy on the reflections of a thin bed |
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| Abstract: | The coal seam is a typical thin bed characterized by much lower elastic impedance than that of the surrounding rock. Coal seam has viscoelasticity and velocity anisotropy and its reflection amplitude changes with frequency. In order to analyze the effect of viscoelasticity and velocity anisotropy on seismic responses of a thin bed, this paper aims at a thin-bed model with strong impedance contrast and simulates seismic responses under three different assumptions, elastic and velocity isotropy, viscoelastic and velocity isotropy, and viscoelastic and velocity anisotropy, through numerical simulation method based on wave equations. Comparison of these seismic reflections shows that the viscoelasticity has non-ignorable influence on the reflection of the thin bed, may reduce the reflected amplitude of elastic waves obviously. While the viscoelastic velocity isotropy and anisotropy have little influence on the reflections of elastic waves of the thin bed. Compared with instantaneous frequencies of the thin bed in elastic and velocity isotropy media, PP-wave instantaneous frequencies in viscoelastic media have a variation with the maximum 8%, while those of PS-wave have only about 3% variation, may be ignored. The above research provides the possibility to predict tectonic coal by using the characteristics of extremely low quality factor of tectonic coal. |
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