Method Research Of One-way Wave-equation Seismic Numerical Simulation

One-way wave equation methods have many advantages in seismic forwardmodeling than full way wave equation, for example, high calculating efficiency, highS/N numerical recording, useful in velocity modeling for its mathching of migrationalgorithm, and etc. Nowadays, one-way wave equation is used for zero-offset seismicnumerical simulation in most times, however, they are scarcely used in the field ofnonzero-offset seismic numerical simulation for the reason of incomplete theory andlacking in efficient algorithm. Taking advantages of one-way wave equation methods,the paper systematically studies the theories of wave-field extrapolation operators,zero-offset seismic modeling of 2D and 3D, nonzero-offset seismic modeling withirregular surface and their applications in seismic layout design and seismic modelingof multi-scale anisotropic media, then develops some new seismic modeling methodsbased on one-way wave equation.The paper has the following innovations. Firstly, extending 2D wave-fieldextrapolation operator to 3D space in F-K domain and applying 3D wave equation torealize fast post-stack forward modeling of 3D geologic body. The method has fastcalculating efficiency and stable algorithm, which can handle variable velocity inlandscape orientation and has extensive suitability. Secondly, expanding theconception of mathematical geophone based on positioning principle and proposingequal-time stacking principle which perfect the theory of nonzero-offset seismicmodeling based on one-way wave equation. Then, based on them, proposing seismicprestack forward modeling with irregular surfaces based on one-way acoustic waveequation. The new method not only has fast calculating efficiency, but also canefficiently control direct wave and multi-reflection wave, and can generate high S/Ncommon-shot records, which is the most suitable tools for seismic modeling andinversion of complex reservoir. Thirdly, based on Hudson theory in rock physics andphysical properties of crack and its surrounding rocks, synthetically considering thewhole characters of respective fractured band and proposing a new numericalsimulation method—Micro Vector and Macro Scale(MIVMAS) aimed to implementseismic simulation in multi-scale anisotropic media simultaneously. In addition,taking the place of ray-tracing method with seismic modeling based on one-way waveequation to design seismic layout, and proposing a new seismic layout designingmethod based on wave equation, which is a great theoretic breakthrough and caneffectively make up the shortcomings of ray-tracing method when facing complexstructures.