Refraction seismic for pre-salt reservoir characterization and monitoring

López, Jorge L.; Neto, F. A. P.; Cabrera, Marlon; Cooke, Sarah; Grandi, S.; Roehl, Deane

doi:10.1190/segam2020-3426667.1

Cited by 15 publications

(6 citation statements)

References 8 publications

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“…In this section, we explore the potential of the α-PGF-FWI for estimating P-wave velocities in a typical Brazilian pre-salt field. In this regard, we consider the realistic acoustic model depicted in Fig 9(a) [80][81][82] as the true model, which comprises a water layer in which the ocean floor is in average of 2km in-depth, followed by post-salt sediments, a salt body with variable thickness and velocity, the pre-salt reservoir, and the bedrock as the model base. By using the true model, Fig 9(a), we generate a seismic dataset considering an OBN acquisition comprising 21 nodes (receivers) equally spaced every 400m, from 6450m to 14450m, deployed at the ocean floor (see the white squares in Fig 9(b)).…”

Section: Brazilian Pre-salt Case Studymentioning

confidence: 99%

Full-waveform inversion based on generalized Rényi entropy using patched Green’s function techniques

et al. 2022

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The estimation of physical parameters from data analyses is a crucial process for the description and modeling of many complex systems. Based on Rényi α-Gaussian distribution and patched Green’s function (PGF) techniques, we propose a robust framework for data inversion using a wave-equation based methodology named full-waveform inversion (FWI). From the assumption that the residual seismic data (the difference between the modeled and observed data) obeys the Rényi α-Gaussian probability distribution, we introduce an outlier-resistant criterion to deal with erratic measures in the FWI context, in which the classical FWI based on l2-norm is a particular case. The new misfit function arises from the probabilistic maximum-likelihood method associated with the α-Gaussian distribution. The PGF technique works on the forward modeling process by dividing the computational domain into outside target area and target area, where the wave equation is solved only once on the outside target (before FWI). During the FWI processing, Green’s functions related only to the target area are computed instead of the entire computational domain, saving computational efforts. We show the effectiveness of our proposed approach by considering two distinct realistic P-wave velocity models, in which the first one is inspired in the Kwanza Basin in Angola and the second in a region of great economic interest in the Brazilian pre-salt field. We call our proposal by the abbreviation α-PGF-FWI. The results reveal that the α-PGF-FWI is robust against additive Gaussian noise and non-Gaussian noise with outliers in the limit α → 2/3, being α the Rényi entropic index.

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Section: Brazilian Pre-salt Case Studymentioning

confidence: 99%

Full-waveform inversion based on generalized Rényi entropy using patched Green’s function techniques

et al. 2022

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“…In this regard, we consider the realistic acoustic model depicted in Fig. 7a [65,66] as the true model, which comprises a water layer in which the ocean floor is an average of 2km in-depth, followed by post-salt sediments, a salt body with variable thickness and velocity, the pre-salt reservoir, and the bedrock as the model base. By using the true 7a, we generate a seismic dataset considering a OBN acquisition comprising 21 nodes (receivers) equally spaced located every 400m, from 6450m to 14450m, deployed at the ocean floor (see the white squares in Fig.…”

Section: Brazilian Pre-salt Case Studymentioning

confidence: 99%

Target-oriented full-waveform inversion based on generalized Rényi entropy using patched Green's function techniques

Barbosa¹,

Silva²,

Barra³

et al. 2022

Preprint

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The estimation of physical parameters from data analysis is a crucial point for the description and modeling of many complex systems. Based on Rényi α-Gaussian distribution and patched Green's function (PGF) techniques, we propose a robust framework for data inversion using a wave-equation based methodology named full-waveform inversion (FWI). We show the effectiveness of our proposal by considering two distinct realistic P-wave velocity models, in which the first one is inspired in the Kwanza Basin in Angola and the second in a region of great economic interest in the Brazilian pre-salt field. We call our proposal by the abbreviation α-PGF-FWI. The results reveal that the α-PGF-FWI is robust against additive Gaussian noise and non-Gaussian noise with outliers in the limit α → 2/3, being α the Rényi entropic index.

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“…There is a number of refracted wave applications in exploration seismology such as migration (Shen and Zhang, 2020), illumination study to reservoir monitoring (Lopez et al, 2020) and, most often, in seismic tomography.…”

Section: Introductionmentioning

confidence: 99%

3D Refraction Travel Time Accuracy Study in High Contrasted Media

Alves,

Santos,

Capuzzo

et al. 2024

Braz J Geophys

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Among all the existing methods to solve the eikonal equation, three methods are chosen to verify accuracy, symmetry, reciprocity and error propagation along large offsets of refracted waves in seismic near surface exploration context. Performance is extremely highlighted nowadays and accuracy is being neglected, then an eikonal solver poorly explored in geoscience is used. A classical solver, the Fast Iterative and the modified Fast Sweeping Method are applied in three modeling schemes: a simple two layers model, a large four layers and a complex benchmark model. The three methods compute the first arrival of refracted waves in high contrast media and the results are compared to the analytical solution. A circular geometry is considered in all experiments to explore the method applicability using full azimuth angles. On the first scheme, the errors in travel time are computed among the three methods using different model sample spacing and we discuss accuracy, symmetry and reciprocity of first arrivals. On the second scheme, three circular receivers are placed in different offsets to check errors along refracted wave propagation. Finally, the third scheme, four shots are strategically positioned over the SEG/EAGE Overthrust model in order to compare the full acoustic wavefield with the eikonal solvers and then check the similarities. Although the focus is on methods accuracy, the algorithm run time is also considered and the comparison shows that the modified Fast Sweeping Method is the most accurate. The most computational efficient eikonal solver is the Fast Iterative Method, but its geoscience applicability needs to be cautious, because of its inaccurate results.

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Refraction seismic for pre-salt reservoir characterization and monitoring

Cited by 15 publications

References 8 publications

Full-waveform inversion based on generalized Rényi entropy using patched Green’s function techniques

Full-waveform inversion based on generalized Rényi entropy using patched Green’s function techniques

Target-oriented full-waveform inversion based on generalized Rényi entropy using patched Green's function techniques

3D Refraction Travel Time Accuracy Study in High Contrasted Media

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