In this paper, we propose a method for time-lapse seismic difference analysis by combining the wavelet transform and nonlinear filtering methods. The nonlinear filter methods we used include median filter and morphological operations, which both show good properties for removing noise and extracting objects. Wavelet transform is a good tool for multi-scale analysis. A combination of the two has the potential to obtain better results than using a single method. We tested our method using both synthetic and real time-lapse seismic data. The results show that the processed time-lapse seismic differences have a clearer background and therefore are easy to interpret.
We propose an inverse data processing method in the plane wave domain for free surface multiple attenuation. Traditionally, inverse data processing is carried out using data matrix in space-frequency (x-?) domain (Berkhout, 2006). For flat-lying layers, the data matrix will have a Toeplitz structure, which means that the inversion can be carried out in frequency wave-number (k-?) domain. Here we propose an alternate method of implementing the inversion in a coupled plane-wave domain where the bandwidth of the matrix can be chosen based on the dominant dip resulting in a stable and fast algorithm.