Study On Gaussian Beam Pre-stack Depth Migration Imaging Method Of VSP Seismic

In order to understand the problem of seismic wave field propagation in medium and complex structures effectively and quickly,the Gaussian beam method is used to study reflected wave imaging in a vertical seismic profile.The vertical seismic profile enables detection close to the target and the detectors that are located underground.It effectively avoids the absorption effect of the surface aerated layer on seismic signals,and can produce high resolution and high precision seismic data.While researching the reflected wave imaging in the vertical seismic profile,we mainly discuss the influence of the geological model,the velocity model and the Gaussian beam initial parameters on imaging results.Also,a model trial calculation for five complex geological structures is carried out,verifying the imaging accuracy of the VSP Gauss ray beam pre-stack depth migration method.We formed three different key technologies for the reflected wave imaging in the vertical seismic profile including:(1)Through analysis of the initial parameters of Gaussian beam migration,imaging conditions and imaging angle,we can implement the method of Gaussian beam pre-stack depth migration imaging in the vertical seismic profile.(2)By establishing a velocity smoothing program for the difference algorithm,and modifying the VSP Gauss ray pre-stack depth migration longitudinal wave velocity model,we can get a more accurate imaging section.(3)We can implement the parallel computation of the Gaussian beam pre-stack depth migration imaging in the vertical seismic profile in Linux by using the MPI message-passing interface,and as a result greatly improve the computational efficiency.The theoretical model and actual data trial indicate that the Gaussian beam pre-stack depth migration imaging method in the vertical seismic profile can produce accurate imaging for complex geological structures,keep the dynamics of the wave field stable,and provide high computing efficiency.The Gaussian beam pre-stack depth migration imaging method in the vertical seismic profile is used in the exploration of the internal structure of the superimposed basin,the imaging results can be clearly seen,and the resolution of the migration section is higher than that of the ground two-dimensional seismic section.