厚风化层覆盖区转换波静校正方法
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摘要
P-SV转换波处理与传统的P-P波处理有很大的不同,如S波静校正、CCP叠加、P-SV速度分析和偏移等,其中最大的难题就是S波静校正问题.S波速度基本不受潜水面的影响,与纵波静校正没有直接相关性,有时横波静校正量能达到纵波静校正量的十倍,用纵波静校正量乘以比例系数来解决横波静校正问题将导致较大误差.同一接收点X和Z分量存在一定的初至时差,该时差代表了P波和S波在低降速带的走时差,可以利用该时差和近地表纵横波速度比信息去除低降速带对横波的影响,得到准确的静校正量.本文利用多分量初至时差推导了较为精确的横波静校正公式,再结合共检波点叠加求取剩余静校正量的方法,形成了完整的转换波静校正配套方法.利用该方法对苏里格气田二维及三维多波地震资料进行了实际处理,数据处理结果证明了该方法的有效性,该方法尤其适用于其他方法难以奏效的风化层较厚地区的横波静校正量求解,该方法也同时考虑了长波长横波静校正问题.
In P-SV seismic data processing,there are some aspects different from conventional P-P seismic data processing,such as S-wave static correction,CCP binning,P-SV velocity analysis and migration.Among them,the most difficult procedure is S-wave static correction.Unlike P-wave velocity,the S-wave velocity is almost unaffected by the water table and generally very low.Hence,the P-wave and S-wave static solutions are largely different from each other,sometimes S-wave statics are near ten times of P-wave′s.So the approximation of the S-wave statics by simply scaling the known P-wave statics will lead to large errors and a good image can not be obtained.It has been proven that the time difference of first break between X and Z component in same receiver represents the travel time difference of P-and S-wave in weathering layer and it can be utilized to calculate S-wave statics.This paper presents an accurate statics expression with respect to the time difference of first break and some velocity ratio parameter of near surface.Combined with residual statics estimated from common receiver stack section,an integrated converted-wave static correction method has been presented.The method was applied to 2D-3C and 3D-3C data processing of Shulige gas field.The results show a good image which indicates that this method is effective for P-SV data processing.This method is especially suitable for statics estimation of thick weathering area where other methods are disabled.Long period S-wave statics are considered simultaneously.
In P-SV seismic data processing,there are some aspects different from conventional P-P seismic data processing,such as S-wave static correction,CCP binning,P-SV velocity analysis and migration.Among them,the most difficult procedure is S-wave static correction.Unlike P-wave velocity,the S-wave velocity is almost unaffected by the water table and generally very low.Hence,the P-wave and S-wave static solutions are largely different from each other,sometimes S-wave statics are near ten times of P-wave′s.So the approximation of the S-wave statics by simply scaling the known P-wave statics will lead to large errors and a good image can not be obtained.It has been proven that the time difference of first break between X and Z component in same receiver represents the travel time difference of P-and S-wave in weathering layer and it can be utilized to calculate S-wave statics.This paper presents an accurate statics expression with respect to the time difference of first break and some velocity ratio parameter of near surface.Combined with residual statics estimated from common receiver stack section,an integrated converted-wave static correction method has been presented.The method was applied to 2D-3C and 3D-3C data processing of Shulige gas field.The results show a good image which indicates that this method is effective for P-SV data processing.This method is especially suitable for statics estimation of thick weathering area where other methods are disabled.Long period S-wave statics are considered simultaneously.
引文
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[13]杨海申,李彦鹏,陈海青.转换波延迟时静校正.石油地球物理勘探,2006,41(1):13-16.Yang H S,Li Y P,Chen H Q.Converted wave delay timestatic correction.Oil Geophysical Prospecting(in Chinese),2006,41(1):13-16.
[14]Heelan P A.On the theory of head waves.Geophysics,1953,18(4):871-892.
[15]Hall D H.Converted waves in refraction surveys overmarkers with variable depth.Geophysics,1964,29(5):733-744.
[16]Ervin C P,McGinnis L D,Otis R M,et al.Automatedanalysis of marine refraction data:A computer algorithm.Geophysics,1983,48(5):582-589.
[17]Taner M T,Wagner D E,Baysal E,et al.A unified methodfor 2-D and 3-D refraction statics.Geophysics,1998,63(1):260-274.
[18]刘伊克,常旭,王辉等.三维复杂地形近地表速度估算及地震层析静校正.地球物理学报,2001,44(2):272-278.Liu Y K,Chang X,Wang H,et al.Estimation of near-surface velocity and seismic tomographic static corrections.Chinese J.Geophys.(in Chinese),2001,44(2):272-278.
[19]冯太林,张学工,李衍达等.折射波地震记录叠加成像方法研究.地球物理学报,2001,44(1):129-134.Feng T L,Zhang X G,Li Y D,et al.Research onmethodology of stack imaging of refractive seismic recording.Chinese J.Geophys.(in Chinese),2001,44(1):129-134.
[20]Liu Y,Wei X C.Propagation characteristics of convertedrefracted wave and its application in static correction ofconverted wave.Science in China Series D:Earth Sciences,2008,51(Suppl.II):226-232.
[21]Li Y P,Gu Y M.A case study of converted-wave explorationin Sulige gas field,China.74th Annual International Meeting,SEG,Expanded Abstract,2004:2517-2520.
[2]Stewart R R,Gaiser J E,Brown R J,et al.Converted-waveseismic exploration:methods.Geophysics,2002,67(5):1348-1363.
[3]Stewart R R,Gaiser J E,Brown R J,et al.Converted-waveseismic exploration:applications.Geophysics,2003,68(1):40-57.
[4]董敏煜.多波多分量地震勘探.北京:石油工业出版社,2002.Dong M Y.Multicomponent Seismic Exploration(inChinese).Beijing:Petroleum Industry Press,2002.
[5]Tatham R H,McCormack M D,Neitzel E B,Winterstein DF.Multicomponent Seismology in Petroleum Exploration.Soc.Expl.Geophys.,1991.
[6]Anno P D.Two critical aspects of shear-wave analysis:Statics solutions and reflection correlations.//Danbom S H,Domenico S N,eds.Shear-wave Exploration:Soc.Expl.Geophys.,Geophys.Dev.Series,1986,1:48-61.
[7]Mari J L.Estimation of static corrections for shear-waveprofiling using the dispersion properties of Love waves.Geophysics,1984,49(8):1169-1179.
[8]Frasier C,Winterstein D.Analysis of conventional andconverted mode reflections at Putah sink,California usingthree-component data.Geophysics,1990,55(6):646-659.
[9]Cary P W,Eaton D W S.A simple method for resolving largeconverted-wave(P-SV)static.Geophysics,1993,58(3):429-433.
[10]Schafer A W.Converted-wave statics methods comparison.CREWES Report,1991..
[11]潘树林,高磊,周熙襄等.一种改进的P-SV转换波静校正方法.石油物探,2007,46(2):143-146.Pan S L,Gao L,Zhou X X,et al.An improved staticcorrection method of converted P-SV wave.GeophysicalProspecting for Petroleum(in Chinese),2007,46(2):143-146.
[12]Li Y P.A new method for converted wave statics correction.72th Annual International Meeting,SEG,Expanded Abstract,2002:979-981.
[13]杨海申,李彦鹏,陈海青.转换波延迟时静校正.石油地球物理勘探,2006,41(1):13-16.Yang H S,Li Y P,Chen H Q.Converted wave delay timestatic correction.Oil Geophysical Prospecting(in Chinese),2006,41(1):13-16.
[14]Heelan P A.On the theory of head waves.Geophysics,1953,18(4):871-892.
[15]Hall D H.Converted waves in refraction surveys overmarkers with variable depth.Geophysics,1964,29(5):733-744.
[16]Ervin C P,McGinnis L D,Otis R M,et al.Automatedanalysis of marine refraction data:A computer algorithm.Geophysics,1983,48(5):582-589.
[17]Taner M T,Wagner D E,Baysal E,et al.A unified methodfor 2-D and 3-D refraction statics.Geophysics,1998,63(1):260-274.
[18]刘伊克,常旭,王辉等.三维复杂地形近地表速度估算及地震层析静校正.地球物理学报,2001,44(2):272-278.Liu Y K,Chang X,Wang H,et al.Estimation of near-surface velocity and seismic tomographic static corrections.Chinese J.Geophys.(in Chinese),2001,44(2):272-278.
[19]冯太林,张学工,李衍达等.折射波地震记录叠加成像方法研究.地球物理学报,2001,44(1):129-134.Feng T L,Zhang X G,Li Y D,et al.Research onmethodology of stack imaging of refractive seismic recording.Chinese J.Geophys.(in Chinese),2001,44(1):129-134.
[20]Liu Y,Wei X C.Propagation characteristics of convertedrefracted wave and its application in static correction ofconverted wave.Science in China Series D:Earth Sciences,2008,51(Suppl.II):226-232.
[21]Li Y P,Gu Y M.A case study of converted-wave explorationin Sulige gas field,China.74th Annual International Meeting,SEG,Expanded Abstract,2004:2517-2520.
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