Study Reviews Operator’s Use of 4D Seismic in Campos and Santos Basins

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 35717, “Experiences With 4D Seismic in Campos and Santos Basins and the Road Ahead,” by Caio J.M.G. Silva, Fabricio B. Nascimento, and Wilson L.R. Filho, Petrobras, et al. The paper has not been peer-reviewed. Copyright 2025 Offshore Technology Conference. _ This paper provides an overview of the application of 4D [time-lapse (TL)] seismic technology by the operator during the past decade and future perspectives. Some results shared in this publication, from both pre- and post-salt reservoirs, include increased hydrocarbon sweep efficiency and recovery factor in siliciclastic reservoirs in the Campos Basin, guidance of intervention in wells, and improvement of predictability of geological and engineering models. Operator Use of Seismic Monitoring Technologies In recent decades, streamer technology has been applied to monitor production-derived effects in many Brazilian post-salt hydrocarbon fields. The main reason for the use of this technology, which has low to medium repeatability, for reservoir monitoring is that it is sufficient to monitor reservoirs with low rock-frame stiffness. The operator obtained success in TL projects using streamer in several siliciclastic reservoirs. Node technology has been developed and improved continuously during the past decade and has been considered a very good cost/benefit alternative for Brazil’s offshore oil fields, especially giant ones. Nodes allow for a rich distribution of azimuths, long offsets, and low frequencies that help processing algorithms such as full waveform inversion (FWI) perform better. Both 3D and 4D data benefit from this acquisition technology, including a presalt field that used streamer and nodes for a time-lapse hybrid project. Another highly repeatable seismic acquisition technology for TL is permanent reservoir monitoring (PRM). Supported by previous experience with this technology in the Jubarte field, the operator contracted a PRM to be installed in the Mero field in 2025. Main Effects of TL Seismic for Brazilian Post-Salt Reservoirs Marlim Field. The sandstones of the Marlim field consist of a post-salt reservoir in the Campos Basin. It spans an area of approximately 150 km2 and is composed of turbidites with excellent permeability and porosity features. Oil production in this reservoir began in 1991. The 4D seismic data in the Marlim reservoir plays a critical role in enhancing reservoir management and optimizing production strategies. By providing a dynamic view of the reservoir over time, 4D seismic allows for the continuous monitoring of fluid movement, which is essential for making informed decisions. In 2022, the operator launched its first revitalization project in the Marlim and Voador fields. The project involved drilling 14 new wells; for supporting them, a new 4D seismic was acquired in 2022. This has enabled the identification of unswept areas and helped to optimize the placement of these wells. The data indicated 4D hardening anomalies extracted from the 4D P-impedance data during the period from 1997 to 2022 that indicated preferential paths of fluid movement. These preferential paths are controlled by thin layers of shale. A gamma ray log illustrates the position of these thin layers capable of controlling the fluid flow in the reservoir. Because of the existence of preferential paths, unswept areas appear to represent new opportunities. Based on the 4D seismic data, the need for adjustments became evident for all 14 planned well locations in the revitalization project. ​​​​​​