基于波动方程的AVO模型数值模拟方法研究

常规的基于褶积的AVO模型数值模拟存在子波参数(如子波类型、主频、延续度等)难以准确设定的缺陷,该文从地震数值模拟的角度出发,提出了一种新的基于波动方程的AVO模型数值模拟方法。该方法首先基于测井声波和密度资料采用Zoeppritz方程计算给定入射角度的反射系数(与常规方法相一致),然后将其外推为二维的水平层状的速度模型和反射系数模型,再采用频率-波数域相移方法进行地震波场的数值模拟计算,最后抽取中间道作为该入射角的AVO模拟记录。虽然该方法的计算量较大,但其有效利用了波动方程数值模拟的优点,可以获得与野外实际观测结果基本一致的模拟记录,具有较强的实际应用价值。

Study on AVO model numerical simulation based on wave equation

The conventional AVO model numerical simulation based on convolution has some problems about wavelet settings, such as the selection of wavelet, wavelet frequency and wavelet continuity and so on. In order to overcome these disadvantages, this paper proposed a new AVO model numerical simulation method which is based on wave equation from the aspect of seismic numerical simulation. Based on sonic and density log data, this method uses Zoeppritz equation or approximate equation to calculate reflection coefficient of a corresponding incident angle firstly （being consistent with the conventional method）. Secondly, extend the reflectance to two-dimensional horizontal layered velocity model and reflection model, and then use the frequency-wave field offset method to calculate numerical simulation of earthquake wave field. Thirdly, extract the seismic trace as AVO numerical simulation of a corresponding incident angle. This method has heavy computation, but it uses advantages of wave equation numerical simulation effectively, and can obtain the same simulation records with the field observation records, so it has practical value.