The effect of anisotropy on amplitude versus offset (AVO) synthetic modelling in Derby field southeastern Niger delta

摘要

The effect of anisotropy on AVO synthetic modelling in Niger delta Derby field has been attempted. The objective of the study is to determine if anisotropic synthetic model can improve amplitude versus offset (AVO) analysis of CDP gathers by comparing them with isotropic synthetic model over shale-gas sand boundaries. Well logs and common depth point (CDP) processed gathers were used for the analysis. The result of the present study revealed that reservoirs in Derby field are overlain by intrinsically anisotropic shale and as such, anisotropic synthetic modelling yields the best fit to CDP gathers than the isotropic synthetic model. However, in conventional processing for AVO analysis, isotropic rather than anisotropic earth models are usually assumed, which could possibly affect the outcome of an AVO-based analysis at large offsets. Therefore, the effect of anisotropy should be incorporated and properly accounted for using the anisotropic synthetic modelling in the processing and interpretation workflows for quantitative AVO analysis in Niger delta to optimise hydrocarbon recovery.