【摘要】 15°有限差分串联偏移在实际应用中存在过偏移问题。笔者通过理论推导和试验,证明过偏移产生于差分误差的积累,而差分误差的大小又取决于速度、频率、界面倾角、空间采样间隔、时间采样间隔、深度步长和差分方式等因素的影响。在此基础上,文中提出了一种可行的差分误差补偿方法,即在原差分波动方程中引入补偿系数R,就可以克服过偏移问题。补偿系数R是△t(时间采样间隔)、△x(空间采样间隔)、△τ(深度步长)、V(层速度)、f(频率)、φ(界面倾角)和B(二阶差分近似系数)的函数。文中分别讨论了这些参数对R的影响,并给出确定R的办法。由实际资料试验说明,该方法保持了原有15°近似方程的优点,并能使60°倾角的界面达到正确的归位。更多还原

【Abstract】 15° finite-difference cascade migration has an overmigration problem in practice.It is shown theoretically and experimentally that overmigration results from the accumulation of difference error, which depends on velocity, frequency, interface dip, spatial sampling interval, time sampling interval, depth step, difference scheme and so on. A feasible difference-error compensation method is described,which introduces compensation coefficient R into the original difference wave equation to remove overmigration. The compensation coefficient R is the function of time sampling interval (△t), spatial sampling interval (△x), depth step (△τ), interval velocity (V), frequency (f), dip (φ) and approximate second-difference coefficient (B). The effect of these parameters on R is discussed, and the method for determining R is given. Real data experiments show that this method not only has the advantages of approximate 15° equation but also brings correct migration to 60°-dip interface.更多还原