Low-frequency sparse double-constrained broadband seismic impedance inversion

Abstract

The reflection coefficient solved by using the traditional impedance inversion method cannot reflect low-frequency information sufficiently and its continuity and resolution are limited, so the quality and resolution of impedance inversion are impacted seriously. In this paper, the advantages of rich low-frequency signals were discussed with the theoretical synthetic seismogram and wavelet simulation as the fulcrum. Then, the low-frequency sparse double-constrained reflection coefficient method was introduced to modify the sparse optimization item, and thus a new method was formed. Finally, based on the broadband data and non-broadband data of the actual work area, the reflection coefficient and impedance inversion solved by the traditional basis-pursuit reflection coefficient inversion were compared and then the calculation results of low-frequency sparse double-constrained reflection coefficient inversion were compared to verify the effect of the modified method. And the following research results were obtained. First, the broadband data with rich low-frequency information is less affected by the side lobe, and its seismic data resolution is higher, which is more favorable for the improvement of inversion accuracy and resolution. Second, in the new method, the L2 norm low-frequency model is added on the basis of the BPDN basis-pursuit denoising problem to constrain the residual, so as to realize the direct solution of the reflection coefficient with low-frequency information. Third, the reflection coefficient and wave impedance solved by using the new method have better continuity and resolution than those solved by using the traditional method and they are in good agreement with the well data. In conclusion, the new method achieves higher resolution on the impedance inversion of broadband data and non-broadband data and the accuracy of impedance inversion is increased, so it has higher application values in predicting the distribution of thin reservoirs.