自适应时窗相干体计算技术及其应用
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摘要
相干体技术是预测断层形态、河道砂体分布及碳酸盐岩裂缝发育状况等的重要技术之一。但在计算相干体时以计算点为中心选取固定长度时窗很难兼顾浅层和深层,即在分析浅层时出现跨多个同相轴,在分析深层(低频带)时因时窗长度不够,在同相轴零点附近相干值易受随机噪声影响;另外,即使时窗大小合适,但在波组起跳点和终止点附近易受邻近波组影响,也难以准确求取同相轴倾角、方位角和相干值等属性;此外,相干体还有较多沿层特征。本文通过地震数据波形自适应地确定时窗,由该时窗计算相干值作为时窗内各样点的相干值;在此基础上,通过计算各视倾角对的相干值估算波形的倾角和方位角。实际资料的处理效果表明,应用本文方法求取的相干体、倾角和方位角属性较为可靠。
Coherence is one of the most important attributes to be used to identify fault form,channel sand body distribution and carbonate fracture development.At present the time window is fixed at center point during coherence calculation.This cannot involve both the shallow and the deep layers.It may cross a few events when analyzing the shallow layer,but within one event when analyzing the deep layer(low frequency zone).The coherence near zero point of events is influenced by random noise.In addition,even if the window size is appropriate,the first break points or the end points of the waveform are easily affected by the adjacent waveform,and it is difficult to obtain accurate dip,azimuth and coherence values.In order to overcome these challenges,we propose a new approach.First the window is chosen adaptively by the seismic data waveform.The calculated coherence value in the window is taken as the coherence value of all the samples in this window.The dip and azimuth of the waveform are estimated by calculation of the apparent dip coherence value.And the dip and azimuth of the adjacent waveforms are then merged.Field data tests indicate that this approach obtains better results.
Coherence is one of the most important attributes to be used to identify fault form,channel sand body distribution and carbonate fracture development.At present the time window is fixed at center point during coherence calculation.This cannot involve both the shallow and the deep layers.It may cross a few events when analyzing the shallow layer,but within one event when analyzing the deep layer(low frequency zone).The coherence near zero point of events is influenced by random noise.In addition,even if the window size is appropriate,the first break points or the end points of the waveform are easily affected by the adjacent waveform,and it is difficult to obtain accurate dip,azimuth and coherence values.In order to overcome these challenges,we propose a new approach.First the window is chosen adaptively by the seismic data waveform.The calculated coherence value in the window is taken as the coherence value of all the samples in this window.The dip and azimuth of the waveform are estimated by calculation of the apparent dip coherence value.And the dip and azimuth of the adjacent waveforms are then merged.Field data tests indicate that this approach obtains better results.
引文
[1]Bahorich M S and Farmer S L.3-D seismic disconti-nuity for faults and stratigraphic features:The coher-ence cube.The Leading Edge,1995,14(10):1053～1058
[2]Marfurt K J,Kirlin R L,Farmer S H et al.3Dseismicattributes using a running window semblance-basedalgorithm.Geophysics,1998,63(4):1150～1165
[3]Marfurt K J,Sudhakar V,Gersztenkorn A et al.Co-herency calculations in the presence of structural dip.Geophysics,1999,64(1):104～111
[4]Gersztenkorn A and Marfurt K J.Eigenstructure-based coherence computations as an aid to 3-D struc-tural and stratigraphic mapping.Geophysics,1999,64(5):1468～1479
[5]Marfurt K J and Kirlin R L.3Dbroadband estimatesof reflector dip and amplitude.Geophysics,2000,65(1):304～320
[6]Cohen I and Coifman R R.Local discontinuity meas-ures for 3-D seismic data.Geophysics,2002,67(6):1933～1945
[7]Lu W K,Li Y D,Zhang S W et al.Higher-order-sta-tistics and supertrace-based coherence-estimation al-gorithm.Geophysics,2005,70(3):P13～P18
[8]Li Y D,Lu W K,Xiao H Q et al.Dip-scanning coher-ence algorithm using eigenstructure analysis and su-pertrace technique.Geophysics,2006,71(3):V61～V66
[9]Marfurt K J.Robust estimates of 3Dreflector dip andazimuth.Geophysics,2006,71(4):P29～P40
[10]Luo Y,Wang Y E,AlBinHassan N M et al.Compu-tation of dips and azimuths with weighted structuraltensor approach.Geophysics,2006,71(5):P29～P40
[11]Donias M,David C,Berthoumieu Y et al.New faultattribute based on robust directional scheme.Geo-physics,2007,72(4):P39～P46
[12]安勇.利用地震波组特征的精细相干扫描方法.石油地球物理勘探,2009,44(4):406～408An Yong.Fine coherent scanning method by seismicwave group feature.OGP,2009,44(4):406～408
[2]Marfurt K J,Kirlin R L,Farmer S H et al.3Dseismicattributes using a running window semblance-basedalgorithm.Geophysics,1998,63(4):1150～1165
[3]Marfurt K J,Sudhakar V,Gersztenkorn A et al.Co-herency calculations in the presence of structural dip.Geophysics,1999,64(1):104～111
[4]Gersztenkorn A and Marfurt K J.Eigenstructure-based coherence computations as an aid to 3-D struc-tural and stratigraphic mapping.Geophysics,1999,64(5):1468～1479
[5]Marfurt K J and Kirlin R L.3Dbroadband estimatesof reflector dip and amplitude.Geophysics,2000,65(1):304～320
[6]Cohen I and Coifman R R.Local discontinuity meas-ures for 3-D seismic data.Geophysics,2002,67(6):1933～1945
[7]Lu W K,Li Y D,Zhang S W et al.Higher-order-sta-tistics and supertrace-based coherence-estimation al-gorithm.Geophysics,2005,70(3):P13～P18
[8]Li Y D,Lu W K,Xiao H Q et al.Dip-scanning coher-ence algorithm using eigenstructure analysis and su-pertrace technique.Geophysics,2006,71(3):V61～V66
[9]Marfurt K J.Robust estimates of 3Dreflector dip andazimuth.Geophysics,2006,71(4):P29～P40
[10]Luo Y,Wang Y E,AlBinHassan N M et al.Compu-tation of dips and azimuths with weighted structuraltensor approach.Geophysics,2006,71(5):P29～P40
[11]Donias M,David C,Berthoumieu Y et al.New faultattribute based on robust directional scheme.Geo-physics,2007,72(4):P39～P46
[12]安勇.利用地震波组特征的精细相干扫描方法.石油地球物理勘探,2009,44(4):406～408An Yong.Fine coherent scanning method by seismicwave group feature.OGP,2009,44(4):406～408
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