论地震约束反演的策略
|
摘要
当前有井约束反演方法（如SLIM，BCI，ROVIM等）多采用以下步骤：①通过逐步修改地层波阻抗值及其厚度值和子波，然后用褶积模型正演出合成地震记录，求其与实际地震道之间的误差；②根据此误差，再作摄动，修改波阻抗模型，直到误差趋于最小为止。然而，由于地震资料的高频信息往往不可靠，故对高频信息的反演是不准确的。本文证明，有效频带之外的地震高频信息永远是多解的，而且是无约束力的。因为高频信息不能通过褶积模型作出合理的检验。文中提供了一种测井约束的简易可行的反演方法。其基本思路是：①在地震资料的有效频带范围内，采用常规的Seislog、Glog等方法，得到地震数据中的中频成分的波阻抗信息；②有关低频和高频成分的波阻抗信息只能由测井资料的内括和外推获得，此时只利用地震资料的层位信息控制内播方向；③将低、中、高频三条渡阻抗剖面相加，得到最终反演结果。
The existing borehole-restricted inversion methods, such as SLIM, BCI,ROVIM and so on, usually consist of the following steps:. Synthetic selsmogram is forward obtained by using convolution model afterwe repeatedly modify not only the wave impedance and thickness of formation butalso wavelet, then it is taken to estimate its errors to a real seismic trace-. Make perturbation, in terms of these errors, to revise wave impedance mod-el until the errors reduce to minimum.However, the inversion of high-frequency informations is not correct becausehigh-frequency seismic informations are usually unreliable. It is proved that high-frequency seismic informations outside effective frequency band will always result inmultiple solutions, without any useful restriction. High-frequency informations cannot be checked reasonably by convolution model.An easy logging-restricted inversion method is recommended here. Its principleinvolves the following essential points:. The wave impedance informations of mid-frequency seismic contents in effec-tive seismic frequency band are obtained by using ordinary Seislog, Glog methodsand so forth.. The wave impedance informations of low- and high-frequency seismic con-tents can be derived only from interpolation and extrapolation of logging data, andherewith the interpolatlon direction is controlled only by horizon informations ofseismic data.. Three wave impedance sections corresponding to low-, mid- and high-fre-quency seismic contents are combined to form the final inversion result.
The existing borehole-restricted inversion methods, such as SLIM, BCI,ROVIM and so on, usually consist of the following steps:. Synthetic selsmogram is forward obtained by using convolution model afterwe repeatedly modify not only the wave impedance and thickness of formation butalso wavelet, then it is taken to estimate its errors to a real seismic trace-. Make perturbation, in terms of these errors, to revise wave impedance mod-el until the errors reduce to minimum.However, the inversion of high-frequency informations is not correct becausehigh-frequency seismic informations are usually unreliable. It is proved that high-frequency seismic informations outside effective frequency band will always result inmultiple solutions, without any useful restriction. High-frequency informations cannot be checked reasonably by convolution model.An easy logging-restricted inversion method is recommended here. Its principleinvolves the following essential points:. The wave impedance informations of mid-frequency seismic contents in effec-tive seismic frequency band are obtained by using ordinary Seislog, Glog methodsand so forth.. The wave impedance informations of low- and high-frequency seismic con-tents can be derived only from interpolation and extrapolation of logging data, andherewith the interpolatlon direction is controlled only by horizon informations ofseismic data.. Three wave impedance sections corresponding to low-, mid- and high-fre-quency seismic contents are combined to form the final inversion result.
引文
1李庆忠.走向精确勘探的道路,石油工业出版社,1994
2李庆忠.符合小层对比原则的砂层内插技术.石油物探,1989,28(1):12～21
2李庆忠.符合小层对比原则的砂层内插技术.石油物探,1989,28(1):12～21
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心