Converted-wave Pre-depth migration based on angle domain

Abstract

In the field of migration velocity analysis,common imaging point gathers is very important for migration velocity analysis(MVA).At present,the common imaging point gathers used for migration velocity analysis mainly contains offset domain common image gathers(ODCIG)and angle domain common image gathers(ADCIG).Since ODCIG is an energy-focusing gather,and there is the kinematics illusion in a complex medium, which leads to its application in MVA restricted. The appearance of ADCIG can solve these problems,it can adapt to multipath propagation of radiation,avoid artifacts produced.The ADCIG obtained from the wave equation migration method was proved to be a gathers which is no illusion,it is also considered the most reasonable gathers currently.In the CMP domain,the author make use of the double square root operator to reverse extension wave field records in this paper,because the migration using double square root operator has an superiority of less aliasing,a simple boundary treatment, without obtaining source wavelet,without consideration migration aperture and a high computing efficiency;In the frequency-wave number domain,the offset information is mapped to the angle domain,then I can get ADCIG. The actual extraction process of ADCIG is transforming the seismic data multi-offset information;in essence,it still is a reflection for multi-offset information of seismic data.Finally,this paper applied the ADCIG gathers to SEG/EAGE rock dome model,the results show,the result of imaging from different reflection angle in ADCIG can be imaging for different areas of underground,and imaging in ADCIG has a feature of high-resolution cross-sectional imaging of seismic waves,less boundary interference.