应用低频信号提高高速玄武岩屏蔽层下的成像质量
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摘要
针对江陵凹陷陵北玄武岩高速屏蔽层下深层成像困难的实际问题,本文首先分析了玄武岩地层的特点及其对波场传播规律的影响,设计了两个相应的理论模型;采用波动方程波场数值模拟技术,通过对深层反射地震信号特征的分析,表明低频地震信号既具有较强的穿透薄高速玄武岩屏蔽层的能力,也具有减弱粗糙表面产生的绕射噪声的能力。将此思路应用于实际资料处理,结果表明利用低频信号可以明显削弱玄武岩高速屏蔽层的影响,提高屏蔽层下深层成像的质量。
In accordance with the practical issue that the imaging below the shielding high-velocity basalt in Lingbei area of Jiangling sag is difficult, the paper first analyzed the characters of basalt and influence on the rule of wavefield propagation and designed two corresponding theoretical models; using wave-equation wavefield numeric simulation technique and analyzing the characters of deep reflection seismic signal showed the low-frequency signals are characterized by having the strong capacity both penetrating thin shielding high-velocity basalt and reducing diffraction noises produced from rough surface. Application of the idea to practical data processing showed that using low-frequency signals can greatly reduce the influence of shielding high-velocity basalt, improving the imaging quality of deep beds below the shielding layer.
In accordance with the practical issue that the imaging below the shielding high-velocity basalt in Lingbei area of Jiangling sag is difficult, the paper first analyzed the characters of basalt and influence on the rule of wavefield propagation and designed two corresponding theoretical models; using wave-equation wavefield numeric simulation technique and analyzing the characters of deep reflection seismic signal showed the low-frequency signals are characterized by having the strong capacity both penetrating thin shielding high-velocity basalt and reducing diffraction noises produced from rough surface. Application of the idea to practical data processing showed that using low-frequency signals can greatly reduce the influence of shielding high-velocity basalt, improving the imaging quality of deep beds below the shielding layer.
引文
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[2]胡中平,管路平,顾连兴等.高速屏蔽层下广角地震波场分析及成像方法.地球物理学报,2004,47(1):88～94
[3]徐文君,於文辉,胡中平.广角反射波的特征及正演模拟.石油地球物理勘探,2006,41(4):390～395
[4]佘德平,吴继敏,李佩等.低频信号在玄武岩地区深层成像中的应用研究.河海大学学报(自然科学版),2006,34(1):83～87
[5]佘德平,吴继敏,李佩等.利用低频信号提高膏盐区成像质量.石油物探,2006,45(3):234～238
[6]Ziolkowski A,Hanssen P,Gatliff R et al.Use of low frequencies for sub-basalt i maging.Geophysical Pros-pecting,2003,51(1):169～182
[7]Planke S,Alvestad E and Eldhol m O.Seismic charac-teristic of basalt extrusive and intrusive rocks.The Leading Eage,1999,18(3):342～248
[8]毛小平,何大伟,辛广柱等.厚层火山岩地震响应特征.石油地球物理勘探,2005,40(6):670～676
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