Impact of Time Lapse Processing on 4D Simultaneous Inversion - The Marlim Field Case Study

This paper presents a 4D simultaneous inversion case study from the Marlim field, offshore Brazil. The paper aims at illustrating the influence of processing for time-lapse AVO inversion.<br>An AVO inversion of the Marlim 4D seismic dataset has been performed on an original dataset, not acquired or processed for time-lapse purposes. A seismic pre-conditioning processing sequence was applied to the post-stack migrated angle stacks to improve the seismic repeatability. The sequence included the creation of a 'common' seismic dataset generated from the coherent signal between base and monitor data. The common dataset is characterized by higher signal-to-noise ratio than both base and monitor vintages. The pre-conditioning efficiently improves the seismic repeatability of the vintages. However, the inversion results show a significant amount of noise contaminating the 4D signal.<br>For this reason, on behalf on Petrobras, the 4D dataset has been subsequently reprocessed in parallel by CGG. The reprocessing involved the application of the same processing sequence to the two vintages. The AVO inversion is being repeated on the new dataset. The 4D parallel reprocessing dramatically increases the repeatability of the two vintages allowing an efficient reduction of the 4D noise for the inversion.