The impact of small faults on seismic impedance inversion

Impedance inversion is one of the most efficient tools to predict and characterize oil and gas reservoirs. Small faults have the ability to reveal the high-resolution information on the target reservoir. However, the impedance information of small faults is always hidden during standard inversion process. Instead, diffracted wavefield indicate high-resolution information beyond reflected wavefield, yet it is biased by reflection-oriented migration. Usually, in the standard inversion scheme, the input is the migrated data and the impedance of small faults is distorted. Therefore, a novel approach is proposed to improve impedance inversion results using the unmigrated data and diffracted wavefield. The input data for inversion is a zero-offset section with identified diffraction events. Forward modelling, designed for the impedance inversion, includes the classical specular reflection plus asymptotic diffraction modelling schemes. A synthetic model, with the fault of half of the wavelength, shows the validation of this novel approach to improve the resolution and accuracy of impedance inversion.