Diffraction separation and imaging based on curvelet domain cascade filter

Diffraction separation plays an important role in high-resolution imaging of small-scale discontinuous geological bodies. These discontinuities or nonuniformities are related to the oil and gas migration path and reservoir space, and they are also common geological hazard factors in engineering. In the common offset domain, diffractions are hyperbolic, while reflections are mostly linear. The difficulty of diffraction separation technology is to suppress the reflected energy while retaining the diffraction energy. Curvelet is a sparse transformation with angle classification. Reflections are distributed in a few coefficient matrices after curvelet transformation, whereas diffractions are the opposite. Based on the significant difference between reflections and diffractions in the curvelet domain, a method of diffraction separation using cascaded filters in the curvelet domain is proposed. Cascade filters in the curvelet domain include high-pass filters and median filters. The adaptive high-pass filter can suppress the low-frequency part of reflections, and the median filter is used to suppress the high-frequency part of reflections. Numerical experiments show that the proposed method has good performance in eliminating tilt and horizontal reflections, as well as the ability to retain the polarity reversal characteristics of diffractions and more energy. Field application further verifies the potential value of this method in solving the identification of complex stratigraphic structures and small-scale discontinuities.