Diffraction Separation And Imaging Based On Anti-stationary Phase Filter And Common Reflection Surface Stack

In recent years,with the deepening of exploration,the exploration potential of large structural oil and gas reservoirs such as anticline are getting smaller and smaller.The importance of small-scale complex structural oil and gas reservoirs such as faults,fractures,sand bodies,salt domes are growing.In order to supplement enough oil supply,we have to develop a exploration method for imaging these small-scale structures.In seismic exploration,these small-scale structures will produce a lot of diffractions.That is to say,diffractions are the main carriers of high resolution information.In order to achieve the purpose of high resolution imaging and improve the recognition accuracy,we need to make the full use of the high resolution information carried by the diffractions.However,the traditional seismic processing workflows and technologies mainly aim at reflections,the diffractions are normally suppressed even filtered because of being treated as noises.Even if the diffractions are migrated correctly,their importance will not be shown,because of their low level of amplitude.The diffraction separation and imaging methods usually achieve their goals through suppressing the reflection energy from large-scale continuous strata and preserve the diffraction energy over imaging/migrating.Then we can highlight the diffraction objects on the migration section.Finally,we can effectively improve the interpretation accuracy of these small-scale diffraction objects such as faults,fractures,sand bodies and salt domes by the joint interpretation of full-wave imaging section and diffraction-only imaging section.In the paper,we first give a detail introduce about the difference between diffraction and reflection,then we point out the feasibility of the separation and imaging of the diffraction.The main works of this paper contain two parts,one is a diffraction imaging method driven by anti-stationary phase strategy in depth domain,and the other is diffraction separation and imaging method based on CRS diffraction stack operator.In the first part,we introduce the anti-stationary phase filter into Depth Gaussian Beam Migration with the help of dip-scanning,kinematic and dynamic ray tracing technologies.In the second part,we build a CRS diffraction operator with the help of the three attributes from CRS stack.Application on models and field data proves their accuracy and validity.On the diffraction-only imaging section,the reflection energy is mostly suppressed and the locations of scattering points are clear enough to identify.