Seismic Migration Imaging Method Based On Arbitrarily Wide-Angle Wave Equation

With the development of seismic exploration, the targets of oil and gas exploration have been turning to complex surface, complex structures and complex reservoir, so seismic imaging technology is being challenged. Pre-stack depth migration based on wave equation is the key technology to achieve precise exploitation and overcome challenge of complex oil and gas exploration. Therefore, seismic migration technologies urgently need to be developed to adapt to the complex geological structure.In this paper, frequency-space domain acoustic arbitrarily wide-angle wave equation (abbreviated as AWWE ) was derived on the basis of the research of AWWE theory, then we get second and third order AWWE migration operator, and solve with finite difference high-split scheme in frequency-space domain, a new migration algorithm was designed and implemented acoustic AWWE equation post-stack and pre-stack migration. Compared with the traditional one-way wave equation (abbreviated as OWWE ) approximation, acoustic AWWE is based on successive division approximation of OWWE , so AWWE can be a more accurate description of the seismic wave propagation. By theoretical deviation analysis and the impulse response test with different parameters, the results show that the optimal AWWE migration operator can more accurately descript the phenomenon of seismic wave and get a greater imaging angle. The orders of AWWE migration operator and the selection of reference velocities are the important factors which can affect the result of migration. Based on the tests of impulse response and theoretical models, we presented the optimization strategies and principles of AWWE migration operator, and gived the significant guidance for the application of AWWE migration into practice. In order to test the effectiveness and adaptability, the new method is applied on the Marmousi model, and compared with the optimized finite difference and fourier finite-difference migration from imaging results and efficiency. Experimental results show that the new algorithm can adapt to the complex geological structure with strong lateral velocity variation and the steep dip. Compared with optimized finite difference and Fourier finite-difference migration method, the parameters optimization of new algorithm is more simple and effective, and can get better imaging on local of complex geological bodies. Compared with the AWWE scheme in the time-space domain, the proposed scheme has some advantages in computational efficiency.The research of pre-stack depth migration with frequency-space domain AWWE shows that the new method is an effective method to image the complex geological structure. So the new method can meet the need of precise exploitation and complex reservoir exploration in our country.