倾斜层状粘滞介质地震记录的合成

SYNTHETIC SEISMOGRAM WITH DIPPING BEDDED VISCOUS MEDIA

地矿部石油物探研究所

在岩性地震勘探中,地震模型研究、振幅随偏移距变化(AVO)研究及地层岩性参数提取研究占有很重要的位置。本文提出了一种地震合成记录的计算方法,该方法综合应用了射线追踪和频率合成技术,可以综合进行介质粘滞性质(即吸收和和频散效应)的模拟和AVO模拟。所研制的相应软件可以计算倾斜层状模型自激自收、共中心点、共炮点三种不同排列的地震响应,包括射线图和地震剖面图,从而为地层岩性模拟、波场特征分析、综合解释、推断结果验证及新方法试验和评价提供了一种新的手段。若干算例结果分析表明,含气砂岩反射具有振幅随偏移距增大的特征,可以用于评价亮点异常,预测含油气层。

To conduct researches on seismic model, AVO and parameters extraction of stratigraphic lithology occupy a very important place in the seismic lithology survey. The author advances a method of calculation for the synthetic seismogram. The calculus can perform the modelling of medium viscosity (i.e. Absorption and Dispersion Effect) and AVO by using Ray Tracing and Frequency Synthetization Technique. The relevant soft -wares developed can compute the seismic response from 3 different spreads (Zero-Offset, CMP and CSP), which include the ray diagram and seismic profile. Thereby it provides a new approach for stratigraphic lithology modelling, wavefield characteristics analysis, integrated interpretation, verification of the interpreted results and the experimentation on and assessment of the the new technique/method. From the analysis made on some examples of the results calculated it shows that the reflections from gas-bearing sandstone are characterized by the increase of amplitude with offset. And it can be served to evaluate the bright spot anomaly and predict the hydrocarbon-bearing horizon as well.