| With the gradual deepening of oil and gas exploration and development,high-precision processing of complex underground structures has become a current research hotspot.VSP technology,with its high signal-to-noise ratio and high resolution,can recognize the advantages of fine structures,and has become a powerful technology for achieving accurate imaging of complex structures.The traditional VSP imaging method regards multiple waves as interference waves,but when the first-order surface multiple waves propagate underground,it can realize the illumination of a reflected wave that cannot reach the shadow area and carry more detailed underground structure information.Therefore,the research on the joint imaging method of VSP first-order surface multiple and reflected waves has important research significance for improving the imaging quality of underground structures.In order to better solve the imaging problems of complex geological structures,this article is based on the principles and advantages of the VSP Gaussian beam method,and uses the C++ language to write a VSP Gaussian beam forward program in the Microsoft Visual Studio 2008 environment.The VSP multi-wavefield seismic numerical simulation results in the theoretical VSP seismic data including the primary reflected wave and the first-order surface multiple wave.On the basis of the Gaussian beam pre-stack depth migration of the primary reflected wave of VSP,the first-order multi-wave Gaussian beam depth migration of the first-order surface of VSP was realized by the mirror extension method.Multiple wave migration results can broaden the imaging range of the VSP primary reflection wave migration at far offsets.Then,based on the least-two-paradigm matching filtering method,the matching factor is obtained,and the imaging results of the primary reflected wave and the first-order surface multiple wave are matched and superimposed to realize joint imaging,and a joint migration profile with higher imaging quality is obtained.Finally,the migration results of actual seismic data show that based on the first-order surface multiple and reflected wave combined Gaussian beam migration imaging method can achieve accurate imaging of complex underground structures,expand the imaging range,and obtain an offset profile with higher imaging quality. |
