罗家地区转换波地震勘探分辨率定量分析

转换波地震勘探分辨率一直是多波地震勘探争论的焦点。基于吸收衰减介质中地震波衰减机理以及纵波、转换波的纵向和横向分辨率定义，对衰减介质中转换波的主频以及分辨率随传播深度的变化进行了分析研究。首先针对胜利油田罗家地区实际地层物性参数，通过理论公式计算分析，获得了研究工区转换波主频、振幅和分辨率随目的层深度的变化规律，计算出其纵波与转换波纵向分辨率的理论交叉点深度在1 966~2 250 m；然后通过高密度3D3C地震资料纵波与转换波剖面的对比分析，显示出罗家地区的实际交叉点深度约为1 980 m，即在探测深度小于该交叉点深度的中浅层，转换波资料的分辨能力要优于纵波资料。浅层气藏识别的应用实例证明了转换波与纵波资料联合解释的良好效果。

The resolution of converted-wave seismic exploration is a constant debate in multi-wave seismic exploration.Based on the attenuation mechanism of seismic wave in absorption and attenuation medium and the definition of both lateral and longitudinal resolution,we studied the variation law of the dominant-frequency and resolution of converted-wave versus the propagation depth.Firstly,aiming at the physical properties with actual data from Luojia region in Shengli Oilfield,by computation and analysis through theoretical formula,the relation between frequency,amplitude,resolution of converted wave and the interval depth is obtained.The “cross point depth” of longitudinal resolution of P-wave and converted-wave is 1 966~ 2 250 m.Comparing the seismic section of P-wave with that of converted-wave obtained from high-density 3D3C seismic data,the results show that the actual “cross point depth” is about 1 980 m in Luojia region,which means at the middle and shallow layer,of which the target depth is less than “cross point depth”,the resolution of converted-wave is higher than that of P-wave.The application to the identification of shallow gas reservoir obtains good results by joint interpretation on P-wave and converted-wave data.