Preserved-amplitude migration with dual-complexity
双复杂介质条件下频率空间域有限差分法保幅偏移

Oil and gas exploration is turning to the areas with irregular topography and complex geologic structures.Prestack depth migration turns out to be a valid way to deal with irregular topography and complex geologic structures."Wave field downward continuation" based on accumulating step by step is a valid way to solve the problem of irregular surface migration.Xwfd pre-stack migration based on wave equation has strong adaptability to the medium which has strong variable transverse velocity and it can be used for migration with dual-complexity.Similar to other conventional migration,it makes just continuation of phase and does nothing to the amplitude.We derived the preserved-amplitude xwfd one-way wave equation operator and added the error compensation caused when solving the wave equation.Based on the xwfd error compensation preserved-amplitude operator,we use the method of "wave field downward continuation" to process the dual-complexity model and real seismic data.The impulse response test and the results of the prestack depth migration for model and real seismic data show that the method is an effective tool for dual-complexity.The error compensation can be done during several continuation steps,compared to conventional Finite Difference Fourier(fft)it has better migration quality.