Seismic Staggered-grid Finite Difference Reverse-time Migration

In order to study the accurate imaging method of seismic data under the complex structure and velocity distribution, this paper firstly introduces the methods and principles of the traditional migration and the reverse-time migration. The wave field recursive calculation in the process of reverse-time migration and imaging are discussed in this paper, deduced suitable method for the staggered-grid finite difference and speed- stress equation of high order staggered grid finite difference scheme is established, formed the recursive calculation equation of wave field. We analyze the boundary conditions, imaging conditions and false interference of reverse-time migration. The boundary reflection has been effectively eliminated by using the attenuation absorbing boundary conditions, reduced the impact on the calculation area of the normal wave field. Reverse-time migration breakthrough the limitation of the dip Angle effectively, improved image of the strong vertical and lateral velocity changes complex model, to deal with the migration of steep dip and many faults complex geological construction has good practical value. Defect of the reverse-time migration is the computations and storages are larger. Discussed the imaging condition of reverse-time pre-stack migration, and select the cross-correlation imaging condition for migration imaging condition of the method. In the process of reverse time migration processing, cross-correlation imaging condition can eliminate false interference, make get better suppress image noise.Using the pulse, hyperbolic reflection wave records as the object of post-stack migration impulse response test, test results verified the theory; The Marmousi model as post-stack migration processing object of trial; Processed migration of a real seismic data from Sichuan; Then pre-stack migration impulse response tests have been carried out, and the theoretical model of multiple shot gathers pre-stack reverse-time migration trial, all good imaging results have been achieved, prove that the method has good migration effect and strong reliability.