平面波射线追踪与面炮波场时间滞后深度成像

面炮(Arealshot)偏移技术是对实际炮集数据按照不同方向传播的平面波进行时间延迟分解并合成组合炮记录,分别进行组合震源下行波的向下波场外推和组合记录上行波的向下波场延拓,在相遇深度得到该方向平面波的反射波成像。本文基于面炮深度偏移技术,充分利用射线追踪计算量小和波动方程波场延拓的良好振幅特性,提出了用平面波射线追踪法计算平面波组合震源下行波前走时和面炮波场滞后时间成像的深度偏移方法,并着重讨论了程函方程有限差分法计算平面波传播时间和组合记录上行波场时间滞后的深度成像方法。通过对Marmousi模型数据的成像检验,表明该法要比积分法偏移效果优越。

Plane wave ray tracing and areal shot wavefield time lags depth imaging

Areal shot migration technique is that the wavefield extrapolation downward for downgoing waves of array source and wavefield continuation downward for upgoing waves of array records are implemented respectively for the shot records composed by time-delay decomposition and synthesis of plane waves propagating in different direction for real shot gather data, and then the imaging of reflection of plane wave in that direction is gained when both of them meet each other. Based on areal shot depth migration technique and fully using small computational effort of ray tracing and good amplitude character of wave equation wavefield continuation, the paper presented using plane wave ray-tracing method to compute travel times of array source downgoing wavefront of plane wave and depth migration method of areal shot wavefield time lags imaging, emphatically discussed using the Eikonal equation finite-difference to compute the propagation time of plane wave and depth imaging method of upgoing wavefield time lags of array records. The test by imaging of Marmousi model data showed the method is superior to the migration by integration method.