碳酸盐岩溶洞横向尺度变化的地震响应正演模拟

Forward simulation of seismic response in carbonate caverns with varied lateral scale

为了模拟碳酸盐岩储层中不同横向尺度溶洞的地震响应特征,设计了具有不同横向尺度但高度和充填物相同的溶洞地质模型,分别采用数值模拟技术和物理模拟技术进行了正演模拟,分析研究了由溶洞宽度变化引起的地震响应变化的特征。研究结果表明,溶洞宽度的变化会引起溶洞反射特征"串珠"中"珠"的数目发生改变,溶洞顶、底位置与溶洞绕射波的相位有对应关系,在偏移剖面中"串珠"尺度与实际溶洞尺度之间存在较大差异。对比同一模型的数值模拟和物理模拟正演结果发现,所得的不同横向尺度溶洞的地震响应特征总的趋势是一致的,但在细节上有所差异,这表明两种正演方法具有互补性,为研究溶洞的"串珠状"地震波反射特征提供了更好的手段。

In order to simulate the seismic responses of caverns with different lateral scale in carbonate reservoirs,we designed cavern geologic models with same height and fillings but different lateral scale,adopted numerical simulation and physical modeling for forward simulation,and analyzed the variation features of seismic responses via the changes of cave width.The results indicate that the changes of cave width will cause the number of'pill'varying in the'string'reflection characteristic,the top and bottom of cave has corresponding relationship with cave diffracted wave.On migration section,the scale of'string'has large contrast with actual cave width.The comparison on forward simulation results of the same model by numerical simulation and physical modeling methods shows that the overall trend of seismic response of different lateralscale caverns is uniform,but difference exists in detail,which indicates that the two methods are complementary and provides better means for study the'string'reflection characteristic of caverns.