| 裂缝、裂隙介质衰减频散研究 |
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| 引用本文： | 张繁昌,路亚威,桑凯恒,黄建平.裂缝、裂隙介质衰减频散研究[J].地球物理学报,2019,62(8):3164-3174. |
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| 作者姓名： | 张繁昌 路亚威 桑凯恒 黄建平 |
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| 作者单位： | 中国石油大学(华东)地球科学与技术学院, 山东青岛 266580 |
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| 基金项目： | 国家自然科学基金（41874146，41874149）资助. |
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| 摘 要： | 为研究裂缝、裂隙介质中波致流引起的衰减,将裂缝看作背景孔隙岩石中非常薄且孔隙度非常高的层状介质,并等价成White周期层状模型.分别考虑不同类型的裂隙和孔隙之间的挤喷流影响,结合改进的Biot方程,推导得到裂缝裂隙介质的刚度与频率的关系.当缝隙中饱含流体时,介质的衰减和速度频散受裂缝、孔隙之间和裂隙、孔隙之间流体流动的显著影响.在低频极限下,裂缝裂隙介质的性质由各向异性Gassmann理论和挤喷流模型获得;而在非常高的频率时,由于缝隙中的压力来不及达到平衡,波致流的影响可忽略.分析表明,裂隙密度主要影响波的衰减,而裂隙纵横比主要控制优势衰减频率和速度显著变化的频率范围;由于不同裂隙的衰减机制不同,衰减和速度频散大小有所差异,但基本趋势相同.
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| 关 键 词： | 裂缝 裂隙 频散 衰减 周期层状模型 |
| 收稿时间： | 2018-04-06 |
Attenuation and dispersion of seismic waves in a cracked-fractured medium |
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| ZHANG FanChang,LU YaWei,SANG KaiHeng,HUANG JianPing.Attenuation and dispersion of seismic waves in a cracked-fractured medium[J].Chinese Journal of Geophysics,2019,62(8):3164-3174. |
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| Authors: | ZHANG FanChang LU YaWei SANG KaiHeng HUANG JianPing |
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| Institution: | School of Geoscience, China University of Petroleum, Qingdao Shandong 266580, China |
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| Abstract: | This work studies the attenuation of seismic waves caused by wave-induced fluid flow in a cracked fractural medium. Fractures are regarded as very thin and porous layers in a porous background, and the fractured medium is equivalent to a periodically layered White model. Considering the influence of squirt-fluid between different types of cracks and pores, the relation between stiffness and frequency in the periodically layered medium is deduced by a modified version of Biot equation. When saturated with fluid, this model exhibits significant attenuation and velocity dispersion due to the wave-induced fluid flowing between fractures and pores or cracks and pores. Under the low frequency limit, the properties of the cracked fractural medium can be determined by the anisotropic Gassmann equation and squirt-fluid model. However at high frequencies, the effect of wave-induced flow can be ignored since the pressure in the cracks has not enough time to reach equilibrium. Analysis shows that wave attenuation is mainly affected by the density of cracks, while the frequency range of significant attenuation and velocity dispersion are mainly controlled by the crack aspect ratio. Owing to different crack attenuation mechanisms, the magnitudes of attenuation and velocity dispersion are different, while their general trends are the same. |
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| Keywords: | Fracture Crack Dispersion Attenuation Periodical layered model |
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