三参量速度信息的求取及应用

Determination of three-parameter velocity informations and the application

对于三线地震勘探，在地下界面倾斜的情况下，其CMP道集的动校正速度不仅随空间位置和t0时间变化，而且与炮点一检波点连线的观测方向有关。为了得到较好的动校正效果，必须进行三参量速度分析，确定地下反射界面的三参量速度信息，即倾向、倾角和均方根速度。笔者介绍的三参量速度分析迭代算法充分利用了采集到的三维地震资料，在叠加道集上求取地层的倾向和倾角，在CMP道集上扫描确定均方根速度，减少了解的不确定性，并且使解释工作量降到最低程度。此法采用先计算方向速度，再进行空间插值的方式，使方位角和倾角插值变得简单可行。实际资料处理结果表明，这种方法可以提高三维地震资料的处理水平。

In the case of slant subsurface interfaces,dynamic correction velocity for CMP trace gathers of 3D seismic data depends on t0,position and observation direction (sourec-receiving line direction). In order to achieve good dynamic correction , we must do three-parameter velocity analysis,namely determination of three-parameter velocity informations of subsurface reflector: dip direction, dip angle and mean square-root velocity. The iteration algorithm for three-parameter velocity analysis fully uses 3D seis-mic data to derive the dip direction and dip angle form stacked trace gathers and todetermine the mean square-root velocity by scanning CMP gathers, thus reducingthe uncertainty of solution and minimizing interpretation. This method needs directional velocity cornputation,followed by spatial interpolation,azimuth and dip interpolations being convenient.It has been practically shown that this method improves 3D seismic data processing.