Study On The Method Of Three-Dimensional Pre-Stack Depth Migration In North Niuju

Because of the gradual in-depth Explorational and Development,as well as the improvement of seismic data processing techniques for more than 30 years in Liaohe Oilfield,seismic data acquisition and processing became one of means for re-growing reserves and production in Liaohe Oilfield.The complicated structure,poor continuity in-phase axis and low SNR can not satisfy the detailed interpretation of geological requirements.But prestack migration,particularly pre-stack depth migration is an ideal seismic imaging technology for the complex areas.With the continuous development and improvement of different pre-stack approches and the precision of exploration,pre-stack migration in the oil and gas exploration is playing an increasingly important role,while the establishment of the correct velocity model is an important assurance.In addition , huge computer resources ,reasonable selection processes and methods are very important for the effective implementation of three-dimensional seismic data pre-stack depth migration.This paper firstly introduces and compares several pre-stack depth migration methods ,including:Kirchhoff integral method,step by step Fourier method,Fourier finite difference method,Generalized Screen method,space-frequency domain finite difference method.Secondly,studying three key steps which are speed estimation,velocity model building and visualization methods of pre-stack depth migration.These three steps integrate and cross-conduct each other in the process of iteration migration.Using of inversion and coherence tomography and other means can improve the accuracy and reliability of the speed model greatly.Finally,combining with the example of North Niuju area points out that the use of pre-stack migration in low SNR ,low coverage areas and other coplex areas shows great success.Moreover,the good consistence of the results of pre-stack migration and well data illustrate the rationality and practicality of the process proposed in this paper,promote the application and development of the three-dimensional pre-stack depth migration and achieve good results with large real significance.