角度域叠前偏移成像研究及应用

Angle domain pre-stack migration imaging studies and application

共炮检距道集在复杂介质中因地震波传播的多路径而存在地下反射位置不准确的问题。共反射角道集由于克服了上述缺陷可在复杂区精确成像,而且能用于AVA分析及保幅偏移成像研究,特别是在大反射角、甚至具有多波至复杂构造区,反射同相轴的振幅和相位得到有效保护。本文以共反射角偏移方法为基础,研究共反射角道集构建、旅行时计算及几何扩散因子获取及偏移拉伸对共反射角道集的影响。运用理论模型数据进行了试算,并以二维实际地震数据对此方法进行了验证,在陡倾角成像方面取得较好效果。研究结果表明角度域共反射角道集更有利于速度建模优化及AVA分析。

For the common offset gathers the multi-path issue of the seismic wave propagation in the complicated medium causes inaccurate reflection points.The common reflection angle gathers overcomes the problem above so the complex subsurface structures can be accurately imaged,the common reflection angle gathers can be used in the AVA analysis and amplitude-preserved migration imaging studies,especially for the complicated structure areas with wide reflection angle and multi-wave arrivals,the amplitude and phase of the reflection events were effectively preserved.Based on the common reflection angle migration method,the common reflection angle gather construction,travel time calculation,and estimation of the geometrical dispersion factor,as well as the influence of the migration stretch to the common reflection angle gather datasets were studied.The trial calculation was conducted with the theoretical model data,2D field seismic data were used to validate the method,excellent results were achieved for imaging the steep structures.The studies results show that application of the common reflection angle gathers could better conduct the velocity modeling optimization and the AVA analysis.