多波多分量地震波场数值模拟及分析

以多波多分量地表资料处理和解释为目的，利用波动方程数值模拟方法对多波多分量地震波场进行了分析和研究。通过单界面和双界面模型正演，对反射纵波（PP波）和转换横波（P-SV波）的识别及波场响应特征进行了研究：①P-SV波速度低，频率低，能量随偏移距的增加而增加，零偏移距处能量为零；②界面反射系数为正时PSV波与PP波极性相反，界面反射系数为负时P-SV波与PP波极性一致；③Z分量和X分量地震记录都是PP波与PSV波的混合信息；④X分量的PP波和PSV波都是由两个极性相反的分支组成的。通过多界面模型正演，分析了转换波勘探的多解性，即地质上的同一个岩性界面有可能对应地震剖面上的两个甚至更多的同相轴。通过理论、模型和实际资料分析，探讨了多波多分量勘探中水平分量旋转处理存在的问题。即通过水平分量旋转处理获得的三分量记录仍然包含了全波场信息，指出通过极化分析，进行三分量同时旋转，可以实现纵波波场和横波波场的完全分离。最后讨论了PP波和PSV波的分辨率，认为P-SV波的纵、横向分辨率均低于PP波。

Numerical simulation of multiwave multi-component seismic wave field

Multiwave multi-component technology is a newly emerging prospecting technology.The muhiwave multi-component seismic wave field was analyzed and studied by numerical simulation meth- od of wave equation.Through single-boundary and double-bounda- ry forward modeling,the reflecting PP wave and P-SV wave were analyzed,so were their wave responding characteristics.The re- sults show that 1) the P-SV wave has a low speed and a low fre- quency,its energy increases with the increase of offset,and the en- ergy is zero for the zero offset,2) the polarity of P-SV wave and that of PP wave is opposite when the boundary reflection coefficient is positive and the polarity of P-SV wave and that of PP wave is u- niform when the boundary reflection coeffieient is negative,3) the seismic record of both Z component and X component are the mixed information of PP wave and P-SV wave,and 4) both the PP wave and the P-SV wave of X component are composed of two branches with inverse polarity.Through multi-boundary forward modeling, the ambiguity of converted-wave exploration was analyzed,that is, a single lithology interface may be correspondent to two or even more events on seismic profiles.By theoretical,model and actual data analysis,the problems in horizontal component revolving pro- cessing of multiwave multi-component exploration were identified, showing that the three-component record obtained by horizontal component revolving processing still involves the information of the whole wave field,and that the simultaneous rotation of three-com- ponent can completely separate P-wave field from S-wave field.Fi- nally,the resolution of both PP wave and P-SV wave were ana- lyzed,indicating that the resolution of P-SV wave,both horizontal and vertical,is lower than that of PP wave.