Understanding refracted wave paths for Brazilian pre-salt target-oriented imaging

Costa, F; Capuzzo, Felipe; Souza, Adriano de; Moreira, Roger Matsumoto; López, Jorge L.; Cetale, Marco

doi:10.1190/segam2020-3426868.1

Cited by 9 publications

(6 citation statements)

References 12 publications

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“…In all these cases, we use the same set of ocean bottom nodes, the difference being the geometry of the shot points. We first performed a wavepath analysis, as suggested by Costa et al (2020), which confirmed that the circular shot OBN acquisition geometry is able to illuminate the pre-salt reservoir (see Fig. 1 and 5).…”

Section: Discussionmentioning

confidence: 59%

“…To identify the velocity model regions where there is better illumination using shot geometry A1, we compute wavepaths following Luo and Schuster (1991). A wavepath analysis using a P -wave velocity model similar to our reference model was performed by Costa et al (2020), using the same shot geometry, considering only the energy of first arrivals. In this work we compute wavepaths by considering the refractions' energy (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…They demonstrated, using 3D raytracing techniques, that shot circles of different radii illuminate different parts of the target area, because of the distorting effects of the complex overlying salt body on the illuminating ray paths. Furthermore, Costa et al (2020) used first-arrival wave paths to study the illumination of the pre-salt reservoir using the same acquisition geometry.…”

Section: Introductionmentioning

confidence: 99%

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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: Discussionmentioning

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Felipe

Capuzzo

Luiz

et al. 2022

Preprint

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“…It is worth mentioning that such a data selection does not guarantee that all selected waveforms are refractions, but most of them are, as analysed by Costa et al. (2020). Finally, to conduct the low‐frequency FWI, we apply a 1‐2‐4‐

5 Hz

‐Ormsby bandpass filter on the seismic data.…”

Section: Brazilian Pre‐salt Case Studymentioning

confidence: 99%

Research note: Application of refraction full‐waveform inversion of ocean bottom node data using a squared‐slowness model parameterization

da Silva,

Costa,

Karsou

et al. 2023

Geophysical Prospecting

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Full‐waveform inversion is a wave equation–based imaging technique for obtaining subsurface model parameters by matching modelled with field data. Full‐waveform inversion is often formulated as a local optimization problem in which the model parameterization influences the gradient preconditioner and the convergence rate associated with the full‐waveform inversion objective function. Model parameterization governs the radiation pattern of the so‐called secondary Born source. In this work, we assess model parameterization effects on the estimation of P‐wave velocities using a three‐dimensional acoustic time‐domain full‐waveform inversion procedure. These include the three commonly used parameterization: velocity, slowness and squared slowness. In this context, we consider a field data set from a deepwater Brazilian pre‐salt field using a recently introduced circular shot ocean bottom node acquisition which favours refracted waves. The results reveal that the squared slowness model parameterization provides a satisfactory trade‐off between the reconstruction of the deep pre‐salt target area and convergence rate, saving 50% of runtime compared to the velocity and slowness cases.

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“…Ideally, 3D target-oriented pre-stack depth migration involves the calculation of reflectivity images exclusively for the identified target zones, aligning with the study's objectives and focusing on the specific area of interest. This target-oriented imaging approach leads to a reduction in the turnaround time required for 3D seismic imaging [10][11][12]. The concept has been a subject of discussion in the literature since the 1990s and gained further traction in the 2000s, as researchers began seeking solutions to address the computational demands of 3D seismic imaging.…”

Section: Introductionmentioning

confidence: 99%

Unveiling Accurate Seismic Imaging through the Advanced Target-Oriented Kirchhoff Migration Method

Dzulkefli,

Abdul Latiff,

Hashim

et al. 2023

Applied Sciences

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A major challenge for the oil and gas industry is expediting the exploration geophysics activity. It is necessary to produce fast and accurate image of the targeted hydrocarbon reservoir, yet it involves extensive dataset due to the target location lies in deeper subsurface. Therefore, target-oriented oil and gas-reservoir imaging is currently seen as more attractive than conventional full-volume migration, in terms of computation efficiency. Through the integration of seismic redatuming with Kirchhoff migration, we presented a target-oriented imaging workflow that can effectively reduce computational cost while simultaneously enhancing the accuracy of the migrated image. Kirchhoff migration is renowned for being one of the simplest and flexible migration techniques, making it straightforward to implement. However, this migration approach is typically avoided in the presence of complex geology, as it tends to introduce artifacts in the images, thereby disrupting the interpretation beneath the complex overburden. Therefore, this paper highlighted the advantages of utilizing seismic redatuming to retrieve data beneath the overburden, followed by the utilization of the redatumed data as input for Kirchhoff migration. With an improved signal to noise ratio, the primary reflection events were amplified, providing clearer representation of the subsurface structure within the hydrocarbon reservoir or targeted area. Additionally, we utilized the benefits of Kirchhoff migration and explored the feasibility of performing patch-based migration in several areas of interest beneath the salt layer. This approach aimed to reduce both the turnaround time and the associated seismic migration costs. The developed workflow then was subsequently put to the test and applied to both a sub-salt SEG Advanced Modeling (SEAM) model and field data situated in East Malaysia. Based on the outcomes of the target-oriented migration, the proposed methodology demonstrated its capability to generate better quality and instant migrated images within the designated region. Furthermore, the feasibility of target-oriented imaging with Kirchhoff migration was substantiated through the integration of seismic redatuming, resulting in significant benefits towards seismic processing, imaging, and interpretation.

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Understanding refracted wave paths for Brazilian pre-salt target-oriented imaging

Cited by 9 publications

References 12 publications

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

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

Research note: Application of refraction full‐waveform inversion of ocean bottom node data using a squared‐slowness model parameterization

Unveiling Accurate Seismic Imaging through the Advanced Target-Oriented Kirchhoff Migration Method

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