The oil and gas industry has established 4D seismic as a key tool to maximize oil recovery and operational safety in siliciclastic and low- to medium-stiffness carbonate reservoirs. However, for the stiffer carbonate reservoirs of the Brazilian presalt, the value of 4D seismic is still under debate. Tupi Field has been the stage of a pioneering 4D seismic project to field test the time-lapse technique's ability in monitoring production and water-alternating-gas (WAG) injection in the Brazilian presalt. Ocean-bottom node (OBN) technology was applied for the first time in the ultra-deep waters of Santos Basin, leading to the Tupi Nodes pilot project. We started with feasibility studies to forecast the presalt carbonate time-lapse responses. The minerals that constitute these carbonate rocks have an incompressibility modulus that is generally twice as large as those of siliciclastic rocks. This translates into discrete 4D signals that require enhanced seismic acquisition and processing techniques to be correctly detected and mapped. Consequently, two OBN seismic acquisitions were carried out. Time-lapse processing included the application of top-of-the-line processing tools, such as interbed multiple attenuation. The resulting 4D amplitude images demonstrate good signal-to-noise ratio, supporting both static and dynamic interpretations that are compatible with injection and production histories. To unlock the potential of 4D quantitative interpretation and the future employment of 4D-assisted history-matching workflows, we conducted a 4D seismic inversion test. Acoustic impedance variations of about 1.5% are reliably distinguishable beyond the immediate vicinity of the wells. These 4D OBN seismic surveys and interpretations will assist in identifying oil-bypassed targets for infill wells and calibrating WAG cycles, increasing oil recovery. We anticipate that studies of the entire Brazilian presalt section will greatly benefit from the results and conclusions already reached for Tupi Field.

Along the past decades the prolific Talara Basin, located at the northwest part of the Peruvian coast, has been intensively studied based mainly on the huge amount of onshore wells on the area. Beside this, contributions come up from 3D seismic. These contributions are stratigraphic and/or structural analysis, which provide suggestions about reservoir communication, fault movement and optimize well positioning. The reservoir characterization methodology applied on this work used 3D PSDM seismic data. The first step aimed to better understand deep reservoir levels (Lower Eocene and Paleozoic), that are less sampled by wells than upper levels (e.g., Middle Eocene). The second step focused on Middle Eocene reservoirs, sampled by tens of wells with a good geological correlation. From well data and geological interpretation, it is well known that Lower Eocene reservoirs are high energy fluvial systemsthis depositional pattern appeared with a distinct seismofacies in the entire seismic cube. Seismic data and well logs showed that Lower Eocene presents more fractures and faults than Middle Eocene. However, the relation between directions and fracture classification as open, semi-open or closed fractures was not conclusive. The seismic facies found at Middle Eocene show sin-depositional differential tectonics movements that could have caused compartmentalization. At this level, seismic facies are very clear, with strong and parallel reflectors, indicating the presence of amalgamated lobes (probably derived from erosion of an eastern ridge located). Identified seismic anomalies were mainly related to structural highs, associated to hydrocarbon saturated reservoirs. An understanding of stress field behavior along geological time is very important to achieve a better trapping model and hydrocarbon migration routes. In this work, the high number of structures observed provided the tools to set up an event chronology. According to the stress history, N70W normal faults acted as migration routes probably during Miocene. Considering the last compressive reactivations (occurred between Upper Eocene and Oligocene) these previously migration routes could be changed to sealing faults.

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