Advanced reprocessing and imaging: enhancing legacy surveys

Abstract

This work demonstrates how fully utilizing a modern reprocessing and depth imaging sequence significantly enhances seismic data quality, thereby extracting additional value from older seismic datasets. Using an example from the northern Browse basin, a case study is presented in which the combination of broadband processing, advanced demultiple techniques and anisotropic earth model building produce significant uplift in the imaging results from what is a historically challenging basin for successful seismic data. The reprocessing sequence was undertaken in two phases. The first phase focused on lowering the noise levels and extending the useful bandwidth of the conventionally acquired seismic data using deghosting techniques. This was combined with 2D and 3D surface demultiple techniques to produce a dataset with low noise levels and a broad signal spectrum for migration. These data were subsequently input to the second phase of the reprocessing which focused on deriving a detailed and accurate earth model. Further anisotropy analysis and well calibration routines were performed to calibrate the earth model to the well data. The final imaging was performed using TTI Kirchhoff prestack depth migration and comparisons were made to the previous time domain imaging results undertaken in 2010.