局部倾角滤波和预测反演联合分离绕射波
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摘要
地震绕射波源于介质非连续性,从地震记录中将绕射波分离出来并进行成像,其结果对研究诸如碳酸盐岩缝洞储层这类复杂非均质储层具有重要意义.对炮集记录进行平面波分解,在地层倾角不大的假设下,反射波和绕射波同相轴在平面波分解剖面上存在较大的倾角差异.基于此,我们提出分步进行绕射波分离的方法:(1)利用局部倾角滤波方法将绕射波的较大倾角信息成分分离出来,此时,余下的部分包含有反射波和残留的低倾角绕射波信息;(2)利用频率-空间域预测反演方法从上述含有反射波和残留的低倾角绕射波信息中分离出残留绕射波成分;(3)将两次分离的绕射波信息相加得到最终的绕射波估计.用该方法能够得到相对完整的绕射波信息,有效地克服了靠单一的倾角差异进行绕射波分离时明显损失低倾角信息,从而影响绕射波成像结果横向分辨率这一问题.理论与实际资料试算验证了该方法的有效性.
It is of great significance to separate seismic diffractions from seismic data and apply the imaged results of these separated diffractions to the research of some complicated reservoirs,the karst reservoir for example.On the planar decomposition section,the dip difference between specular reflection events and diffraction events is remarkable in the case that the dips of reflection interfaces are small.Based on the above facts,we propose a hybrid method for diffraction separation:(1) We divide each planar decomposition section into two portions by local dip filtering: the portion d1 mainly containing diffraction information with high dip and the portion 1 containing the specular reflection r and residual diffraction information with low-dip(d2);(2) The separation of specular reflection r and residual diffraction information d2 from 1 obtained in step(1) is conducted by prediction inversion in F-X domain;(3) d2 added to d1 makes the estimation of diffractions.This separation method can get relatively complete diffraction information,which effectively avoids the problem appearing in the general filter methods based only on dip attribute that low dip portion of diffraction is lost and thus narrowing the spatial bandwidth of the diffraction which will damage the lateral resolution.The feasibility of the proposed method is proven by both theoretical and real data tests.
It is of great significance to separate seismic diffractions from seismic data and apply the imaged results of these separated diffractions to the research of some complicated reservoirs,the karst reservoir for example.On the planar decomposition section,the dip difference between specular reflection events and diffraction events is remarkable in the case that the dips of reflection interfaces are small.Based on the above facts,we propose a hybrid method for diffraction separation:(1) We divide each planar decomposition section into two portions by local dip filtering: the portion d1 mainly containing diffraction information with high dip and the portion 1 containing the specular reflection r and residual diffraction information with low-dip(d2);(2) The separation of specular reflection r and residual diffraction information d2 from 1 obtained in step(1) is conducted by prediction inversion in F-X domain;(3) d2 added to d1 makes the estimation of diffractions.This separation method can get relatively complete diffraction information,which effectively avoids the problem appearing in the general filter methods based only on dip attribute that low dip portion of diffraction is lost and thus narrowing the spatial bandwidth of the diffraction which will damage the lateral resolution.The feasibility of the proposed method is proven by both theoretical and real data tests.
引文
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[2]Tcheverda V,Pozdnyakov V A.3Dfocusing transformation:reliable tool for imaging of scattering objects.∥Abstracts ofSEG/New Orleans 2006Annual Meeting,2006:2564-2568.
[3]Khaidukov V.Diffraction imaging by a focusing-defocusingapproach.∥Expanded Abstracts of 73rd Annual InternatSEG Mtg,2003:26-31.
[4]Nowak E J,Imhof M G,Tech V.Diffractor localization viaweighted Radon translations.∥Expanded Abstracts of 74thAnnual Internat SEG Mtg,2004:10-15.
[5]Bansal R,Imhof M G.Diffraction enhancement in prestackseismic data.Geophysics,2005,70(3):V73-V75.
[6]Harlan W S,Claerbout J F,Rocca F.Signal/noise separationand velocity estimation.Geophysics,1984,49(11):1869-1880.
[7]Fomel S.Applications of plane-wave destruction filters.Geophysics,2002,67(6):1946-1960.
[8]Turhan Taner M.Separation and imaging of seismic diffractions using plane-wave decomposition.∥Abstracts of SEG/New Orleans2006Annual Meeting,2006:2401-2405.
[9]曲寿利,朱生旺,赵群等.碳酸盐岩孔洞型储集体地震反射特征分析.地球物理学报,2012,55Qu S L,Zhu S W,Zhao Q,et al.Analysis of seismic reflection characters for carbonate Karst reservoir.Chinese J.Geophys.(in Chinese),2012,55(6):2053-2061.
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