双参数层析校正的聚焦深度分析

叠前偏移速度分析的难点是速度模型的迭代修正。本文以深度聚焦分析和双参数反射层析成像两种不同的速度估算方法为基础，通过时移，利用克希霍夫积分法深度偏移获取深度聚焦分析面板，利用CRP层析成像方法来调整速度和深度模型，不仅克服了常规深度聚焦分析中模型修正公式的三个基本假设条件(小倾角反射层、小偏移距和简单上覆层)的限制，而且推出了一种新的地震速度估计和修正的方法。该方法通过聚焦深度分析和CRP射线追踪来获得剩余时差，避免了叠前反射层析成像繁重的旅行时拾取工作。从数值模型的计算结果看，本文方法对常规速度分析难以处理的速度横向剧烈变化和复杂上覆层问题有较好的适应性和处理效果。

Focus depth analysis for dual-parameter tomographic correction.

The difficulty of velocity analysis in prestack migration lain on iterative update of velocity model.Based on two different velocity evaluation methods-depth focus analysis and dual-parameter tomographic image and through time shift,the paper uses Kirchhoff depth migration to yield depth focus analysis panel and uses tomographic imaging method on common-reflection-point (CRP) gathers to modify the velocity and depth models,that not only overcame the limits of the basic hypotheses (reflection in small angle,short offset and simple overburden) used by model-modified formula in common depth focus analysis,but also deduced a new method for seismic velocity evaluation and modification.The method gained residual moveout by focus depth analysis and CRP ray-tracing,which avoided tedious pick-up of travel-time in prestack reflection tomography.The computation results of numeric models showed that the method presented by the paper has good adaptability and processing effects in the areas having laterally rapid variation of velocity and complex overburden that common velocity analysis methods are difficult to handle.