OBN for pre-salt imaging and reservoir monitoring – Potential and road ahead

Cypriano, Luis; Yu, Zhiyi; Ferreira, Denis; Huard, Benjamin; Pereira, Roberto Guimarães; Jouno, Florian; Khalil, A.; Urasaki, Eduardo; Cruz, Nathalia da; Yin, Ailin; Clarke, Dan; Jesús, Carlos de

doi:10.22564/16cisbgf2019.318

Cited by 11 publications

(2 citation statements)

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“…The issues are associated with the complex geometry of the overlying thick layer of salt, the deep carbonate reservoirs and an ultra-deep water layer which exceeds 2 km . The requirement to improve seismic imaging and reservoir characterization in ultra-deep water regions has encouraged using new seismic data acquisition technologies, such as the oceanbottom-node (OBN) acquisition, together with robust techniques associated with full-waveform inversion (FWI) (Barragan et al, 2019, Cypriano et al, 2019, Thedy et al, 2015, Wang et al, 2019.…”

Section: Introductionmentioning

confidence: 99%

Target-oriented refraction waveform inversion: A Brazilian pre-salt case study

Felipe

Capuzzo

Luiz

et al. 2022

Preprint

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The ocean-bottom-node (OBN) technology has been increasingly used to characterize the Brazilian pre-salt reservoirs. The independence between the geometries of seismic sources and receivers, enabled by an OBN survey, permits designing wide-aperture acquisition geometries that favour the recording of refracted waves from ultra-deep reservoirs. In this context, we present a target-oriented full-waveform inversion (FWI) methodology to evaluate the inversion of refracted waves simulated using a realistic velocity model inspired by typical Brazilian pre-salt oil fields. In our tests we compare three acquisition geometries, using the same node configuration on the seabed, but different source geometries: (i) circular shot geometry, (ii) conventional OBN geometry, (iii) long-offset OBN geometry. We perform a wavepath analysis to investigate the illumination of the target region promoted by the refracted waves of a circular shot OBN survey. The wavepath analysis suggests that Brazilian pre-salt reservoirs may be well illuminated using the much fewer source points in a circular shot acquisition geometry. The FWI results with synthetic data show that refracted waves bring important information from the ultra-deep reservoirs which are indispensable for obtaining a reliable final velocity model. We show that adding a low-cost circle shot geometry to a conventional OBN survey delivers improvements from the long-offset data that are comparable to those obtained from the much more expensive long-offset OBN geometry. Furthermore, these results suggest that the long-offset and multi-azimuth dataset has great potential to improve the reservoir characterization in deep-water exploration marine settings.

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Section: Introductionmentioning

confidence: 99%

Target-oriented refraction waveform inversion: A Brazilian pre-salt case study

Felipe

Capuzzo

Luiz

et al. 2022

Preprint

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“…sources and receivers geometry, sail line direction, etc.). This becomes even more critical for reservoirs with low 4D signal, like the Brazilian pre-salt reservoirs in Santos Basin (Cypriano et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Impact of the Non-repeatability of Sources and Receivers in Ocean Bottom Acquisitions - a Synthetic 2D Study in Santos Basin Pre-salt

et al. 2021

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Time-lapse seismic feasibility studies support acquisition and processing planning, being also essential for a good 4D interpretation. In this work, we study the effects of source and receiver non-repeatability in time-lapse acquisitions with ocean bottom sensors. We perform 2D acoustic seismic modeling with high-resolution property models in two distinct dates. To simulate source and receiver non-repeatability, different acquisition geometries are considered for each vintage. The synthetic data are compared in terms of time-lapse amplitude and time-shifts, and repeatability is quantified via the normalized root mean squared attribute (NRMS). For the parameters considered in our study, the deterioration of NRMS seems to be dominated by the non-repeatability of the receivers, with source non-repeatability having a lower contribution. We believe the results presented in this work are a first step towards a more robust methodology for time-lapse feasibility studies, which incorporate imaging uncertainties.keywords: 4D seismic, reservoir geophysics, seismic monitoring, time-lapse seismic Impacto da não-repetibilidade de fontes e receptores em aquisições de fundo oceânico - um estudo sintético 2D no Pré-sal da Bacia de SantosEstudos de viabilidade sísmica 4D são essenciais para suportar o planejamento, aquisição, processamento e interpretação da sísmica time-lapse. Neste trabalho, investigamos os efeitos da não-repetibilidade de fontes e receptores em aquisições offshore com sensores de fundo oceânico. Modelagens acústicas 2D por diferenças finitas, com modelos de propriedades de alta resolução, foram realizadas para diferentes datas de aquisição. Os dados sintéticos foram comparados e os atributos de amplitude 4D e time-shift foram calculados. A repetibilidade foi quantificada com o uso do atributo normalized root mean squared (NRMS). Para os parâmetros considerados neste estudo, a piora do NRMS parece ser dominada pela não-repetibilidade dos receptores, enquanto a não-repetibilidade da fonte aparentou ter um papel secundário. Acreditamos que os resultados apresentados aqui constituem um primeiro passo para estudos de viabilidade 4D mais robustos, que incorporem incertezas de aquisição e imageamento.palavras-chave: sísmica 4D, geofísica de reservatórios, monitoramento sísmico, sísmica de lapso de tempo

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