Prestack AVO inversion based on the vectorised reflectivity method with blockiness constraint

摘要

Many oil fields in the world are continental clastic facies lake basins, which develop many thin interbedded reservoirs. Conventional AVO inversion methods based on Zoeppritz equation are not suitable for the identification and characterisation of such reservoirs. In this study, we propose a new inversion method based on the vectorised reflectivity method with blockiness constraint in order to obtain the inversion results with high accuracy and resolution. The vectorised reflectivity method can provide the 1D analytical solution of elastic wave equation, and simulate full-wave field. Therefore, it overcomes the problems caused by internal multiples, converted waves, transmission loss, and reservoir thickness in the thin interbedded reservoirs. Applications of the synthetic data and field data demonstrate that, compared with the conventional method based on Zoeppritz equation, the proposed method shows advantages in estimating the elastic parameters of the thin interbedded reservoirs. In addition, the inversion of blocky model and logging data demonstrate that the differential Laplace constraint gives higher resolution and better numerical stability than Gaussian and Cauchy constraints. The computational efficiency and high accuracy that the proposed approach provides are expected to be exploited in characterising thin interbedded reservoirs in many fields.