地震水平叠加技术道集内反射点离散量的分析

Analysis of the reflection point discrete quantity in seismic horizontal stack gathers

常规地震水平叠加技术采用共中心点道集表达共反射点道集的信息,这使其具有很大局限性。为了计算CMP道集内各道离散量的大小,分析离散量对地震资料的影响程度,首先采用模型分类方法解决数学建模的困难,然后针对分类后的模型计算出CMP道集内各道的离散量的大小,最后分析离散量对资料的影响程度,总结离散量与煤层倾角、煤层埋深、野外采集的炮检距的变化关系及变化规律。模型的空间离散量和剩余时差的计算结果表明,一般情况下,地震CMP道集内离散量和剩余时差数值均较大、能够形成明显的混叠效应,影响到地震资料的精度和分辨能力。根据煤层埋深、倾角情况设计适合的采集排列长度,从而控制离散量和剩余时差对地震资料的影响程度,该方法具有一定实用价值。

The seismic horizontal stacking technique uses the CMP gather to express the information of the CDP gather.This is an important limitation.This study focuses on calculating the size of the discrete quantities in the CMP gather and analyzing their influence on seismic data.First,a model classification method was used to overcome the difficulties in mathematical modeling.Then,the discrete quantities in the CMP gathers were calculated according to the classification method.Finally,the influence of the discrete quantities on the seismic data was analyzed.Additionally,the relationships between the discrete quantities and the coal dip angle,coal burial depth,and offset were summarized.The results of calculations using different models for evaluating the discrete quantities and residual moveout indicated that the values for CMP gathers were generally high.This resulted in evident aliasing that affected the accuracy and resolution of the seismic data.According to the depth and dip angle of the coal seams,an appropriate offset was determined to control the influence of the discrete quantities and residual moveout on the seismic data.It is concluded that the proposed method has a certain practical value.