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吴国明,杨海生,龚小金:在吸收边界条件下的双变差分法偏移,《石油地球物理勘探》,21(2)1986:208～214目前波动方程差分法偏移中存在着三个问题:①为了消除边界引起的假反射干扰,使用了边界镶边法,这样增加了许多计算机运算时间;②偏移延拓时,采用固定的小延拓步长,这不仅加大了计算机工作量,也使累积误差增大;③横向变速偏移时,用直接求ρ因子公式,计算量非常大,而且,如果速度函数有突变点时,会使偏移计算无法进行下去。本文针对上述问题,提出了在吸收边界条件下双变差分法偏移技术。采用吸收边界条件来消除边界假反射;用自适应延拓步长△τ代替固定延拓步长,从而大大节省了机器运算时间,提高效率可达50%以上;对于横向变速偏移,用递推求ρ因子的方法可以节省机器时间1/3左右;对速度采用纵横向三点光滑处理,使程序适应了具有突变点速度函数的偏移计算。采用本文的方法在模型和实际资料处理中见到了明显效果。
Wu Guoming, Yang Haisheng, Gong Xiaojin: Bi-variogram Offset Under Absorbing Boundary Conditions, “Petroleum Geophysical Prospecting”, 21 (2) 1986: 208 ~ 214 There are three problems in the migration of the differential equations by wave equation : ① In order to eliminate the boundary reflection caused by false reflection, the use of the border trim method, thus increasing the number of computer computing time; ② offset extension, the use of fixed small extension step, which not only increased the workload of the computer , But also the cumulative error increases; ③ lateral speed offset, the direct use of ρ factor formula, the calculation is very large, and if the speed function has a mutation point, will make the offset calculation can not go on. In view of the above problems, this paper proposed a double-difference method migration technique under absorbing boundary condition. Adopt the absorbing boundary condition to eliminate the boundary false reflectance, and use the adaptive extension step △ τ instead of the fixed extension step, thus greatly saving the machine operation time and improving the efficiency up to over 50%. For the lateral shift offset, The method of calculating ρ factor can save about 1/3 of the machine time. The vertical and horizontal three-point smoothing is applied to the velocity to make the program adapt to the offset calculation with the abrupt point velocity function. The method of this article has shown obvious effect in model and actual data processing.