Seismic singularity attribute and its applications in hydrocarbon detection

Abstract The onset function is introduced to extend the traditional formation conversion model, and the singularity data is used to quantify the transit characteristics of the formation velocity. Moreover, the traditional convolution model is used to identify the transmission of the singularity data from acoustic impedance to composite seismogram. The singularity characteristics of formation medium are preserved in the seismogram and they can be considered as a natural seismic attribute that can delineate the formation boundaries accurately. With the mono-scale fractional-order Gaussian wavelet transformation algorithm, the wavelet transform modulus maximum points are traced by taking the disappearance or appearance of the maximum as the criterion for singularity index calculation. When the maximum approaches zero, the corresponding order number of fractional-order Gaussian wavelet is just the Holder index desired. In this regard, it is proposed to detect the hydrocarbons with the singularity data of the seismogram. It is demonstrated with both the geologic model and the actual seismic data for a gas field in the Sichuan Basin, which shows that the singularity index can be considered as a key reference for hydrocarbon detection.