三维宽带约束反演中的正反演联合层位标定及子波外推技术
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摘要
在现今的各种地震反演商用软件中，只给用户提供层位标定后深—时转换的测井速度曲线，不提供深—时转换后的原始测井速度曲线。这样做对层位标定要求不严的Glog等类软件是可行的。但在宽带约束反演中，层位标定正确与否却关系到宽带约束反演的成败。因为不同的层位标定，可得到不同的子波。为此，我们提出了正反演联合层位标定技术。首先用测井的速度、密度、反射系数求取合成记录，然后将此合成记录与井旁地震道进行对比，并不断修改反射系数序列，重新求取合成记录，直到两者吻合为止。在上述正演层位标定的基础上，再对做漂移和不做漂移的声波曲线求取的合成记录分别进行反演，得到漂移测井速度曲线和原始测井速度曲线。再将两者进行对比，不吻合再修正反射系数序列，直到漂移测井速度曲线与原始测井速度曲线吻合为止。该方法在实际应用中取得了很好的层位标定结果和反演效果。在三维宽带约束反演中，采用了纵、横剖面上子波插值技术，使多井三维地震反演更合理、更准确。
Nowaday commercial seismic inversion softwares only offer users the log velocity curves for depth-time conversion after horizon calibration,without the raw logvelocity curves after depth-time conversion. Such practice is feasible only in Glogsoftwares in which requirements for horizon calibration are not strict.However,innew wide-band restriction inversion, horizon calibration quality results in successor failure of this inversion because different horizon calibrations bring differentwavelets. Thus,forward-inversive horizon calibration technique is advanced to copewith the problem. The new technique consists of the following steps:·Derive synthetic seismogram from log velocity, density and reflection coeffi-clent.·Compare the synthetic seismogram with borehole-side seismic trace so as toget the revised reflection coefficients for better synthetic seismogram until the newsynthetic seismogram desirably coincides with the borehole-side seismic trace.·After forward horizon calibration, inversions of synthetic seismogramswhich were derived respectively from drifted and non-drifted acoustic log curves areconducted to obtain drifted log velocity curve and raw log velocity curve.·The drifted and raw log velocity curves are compared each other to revise reflection coefficient series until the drifted log velocity curve coincides desirably withraw log velocity curve.This technique produces satisfactory horizon calibration result and inversion effect. In our 3-D wide-band restriction inversion, wavelet interpolations in P-waveand S-wave sections are done to make multi-borehole 3-D seismic inversion verysatisfac to ry.
Nowaday commercial seismic inversion softwares only offer users the log velocity curves for depth-time conversion after horizon calibration,without the raw logvelocity curves after depth-time conversion. Such practice is feasible only in Glogsoftwares in which requirements for horizon calibration are not strict.However,innew wide-band restriction inversion, horizon calibration quality results in successor failure of this inversion because different horizon calibrations bring differentwavelets. Thus,forward-inversive horizon calibration technique is advanced to copewith the problem. The new technique consists of the following steps:·Derive synthetic seismogram from log velocity, density and reflection coeffi-clent.·Compare the synthetic seismogram with borehole-side seismic trace so as toget the revised reflection coefficients for better synthetic seismogram until the newsynthetic seismogram desirably coincides with the borehole-side seismic trace.·After forward horizon calibration, inversions of synthetic seismogramswhich were derived respectively from drifted and non-drifted acoustic log curves areconducted to obtain drifted log velocity curve and raw log velocity curve.·The drifted and raw log velocity curves are compared each other to revise reflection coefficient series until the drifted log velocity curve coincides desirably withraw log velocity curve.This technique produces satisfactory horizon calibration result and inversion effect. In our 3-D wide-band restriction inversion, wavelet interpolations in P-waveand S-wave sections are done to make multi-borehole 3-D seismic inversion verysatisfac to ry.
引文
1 周竹生,周熙襄.宽带约束反演方法.石油地球物理勘探,1993,28(5):523～536
2 李庆忠.走向精确勘探的道路,石油工业出版社,1994
3 黄绪德.反褶积与地震道反演,石油工业出版社,1992
2 李庆忠.走向精确勘探的道路,石油工业出版社,1994
3 黄绪德.反褶积与地震道反演,石油工业出版社,1992
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