scholarly journals COMPARISON OF TRAVEL-TIME APPROXIMATIONS FOR UNCONVENTIONAL RESERVOIRS FROM SANTOS BASIN

2017 ◽  
Vol 35 (4) ◽  
pp. 273 ◽  
Author(s):  
Nelson Ricardo Coelho Flores Zuniga ◽  
Eder Cassola Molina ◽  
Renato Luiz Prado
Keyword(s):  
Travel Time ◽  
Complexity Analysis ◽  
Numerical Study ◽  
Optimization Criterion ◽  
Hydrocarbon Exploration ◽  
Unconventional Reservoirs ◽  
Ocean Bottom ◽  
Converted Wave ◽  
Reflection Seismic ◽  
Multicomponent Seismic

ABSTRACT. The reflection seismic method is extremely important for the hydrocarbon exploration. With more complex geological structures, as the pre-salt from Santos Basin, the reservoir exploration becomes more challenging and the multicomponent seismic investigation improves its mapping and characterization. To obtain multicomponent seismic data of an offshore survey it is necessary to use the OBN (Ocean Bottom Nodes) technology. The converted wave behavior, the large offsets and the difference of datum between source and receptors for layered media, results in strong nonhyperbolic travel-time events. Furthermore, the complexity and peculiarities of some unconventional reservoirs found in the pre-salt also increase the difficulty to perform the velocity analysis. For these reasons, it is necessary to use nonhyperbolic multiparametric travel-time approximations to control the nonhyperbolicity. Here we perform the comparison of nonhyperbolic travel-time approximations of seismic reflection events derived from geological models. The numerical study was considered as an inverse problem and it was treated according to an optimization criterion. The complexity analysis was performed in order to understand the behavior of each approximation concerning the unicity. After the computation of the relative errors between the observed curve and the calculated curve for each nonhyperbolic approximation, it was possible to find out the one with the highest accuracy for the events tested here.  Keywords:  multicomponent, OBN, nonhyperbolic.RESUMO.Ométodo sísmico de reflexão é extremamente importante para a exploração de hidrocarbonetos. Comestruturas geológicasmais complexas, como o pré-sal da Bacia de Santos, a exploração de reservatórios se tornamais desafiadora e a utilização da sísmica multicomponente promove o mapeamento e caracterização estrutural. Para obter-se dados de sísmica multicomponente em um levantamento offshore é necessário utilizar a tecnologia OBN (Ocean Bottom Nodes ). O comportamento de ondas convertidas, longos afastamentos e diferença de datum entre fonte e receptor pra meios estratificados resultam em uma forte não-hiperbolicidade dos eventos de tempos de trânsito. Além disso, a complexidade e peculiaridades, de alguns reservatórios não convencionais encontrados no pré-sal, também aumentam a dificuldade em realizar a análise de velocidades. Por estes motivos, é necessário usar aproximações não-hiperbólicas multiparamétricas de tempos de trânsito para controlar os efeitos da não-hiperbolicidade. No presente trabalho, foi realizada a comparação de aproximações não-hiperbólicas de tempos de trânsito de eventos sísmicos de reflexão provenientes de modelos geológicos. O estudo numérico foi considerado como um problema inverso e foi tratado de acordo com um critério de otimização. A análise de complexidade foi realizada para compreender o comportamento de cada aproximação com respeito a unicidade. Após computar os erros relativos entre a curva observada e as calculadas com cada aproximação, foi possível descobrir a aproximação que apresentou maior precisão para os testes realizado.Palavras-chave: multicomponente, OBN, não-hiperbólicas.

scholarly journals Comparative analysis of nonhyperbolic multiparametric travel-time approximations of multicomponent seismic data considering difference of depth between source and receiver using OBN technology

2019 ◽  
Vol 37 (4) ◽  
pp. 397
Author(s):  
Nelson Ricardo Coelho Flores Zuniga ◽  
Eder Cassola Molina ◽  
Renato Luiz Prado
Keyword(s):  
Comparative Analysis ◽  
Travel Time ◽  
Seismic Data ◽  
Complexity Analysis ◽  
Velocity Analysis ◽  
Ocean Bottom ◽  
Multicomponent Seismic ◽  
Calculated Curve ◽  
The Difference ◽  
Wave Conversion

AbstractThe processing of multicomponent seismic data is already a challenge concerning the velocity analysis. When it is performed for offshore survey, the difficulty increases a lot more with the use of OBN (Ocean Bottom Nodes) technology. The ray tracing asymmetry generated by the wave conversion and the difference of datum between source and receptor are not the only factors which contribute for a strongly nonhyperbolic travel-time event. The layered subsurface models and the large offsets employed in the offshore surveys make the nonhyperbolicity even stronger. Aiming to solve this problem, eight approximations to perform the velocity analysis were tested for two models. The complexity analysis of each nonhyperbolic multiparametric approximation was also studied to understand their behaviors during the optimization process. The relative error between the observed curve and the calculated curve with each approximation was computed for PP and PS reflection events of two models. With these informations, it was possible to determine which approximation is the most reliable one for this kind of models.Keywords: multicomponent, OBN, nonhyperbolic, multiparametric. ResumoO processamento de dados sísmicos multicomponentes já é um desafio com relação à análise de velocidades. Quando realizado para levantamentos marítimos, a dificuldade aumenta muito mais com o uso da tecnologia OBN (Ocean Bottom Nodes). A assimetria no traçado de raios gerada pela conversão de onda e pela diferença de profundidade entre fonte e receptor não são os únicos fatores que contribuem para um evento de tempos de trânsito fortemente não-hiperbólico. Os modelos estratificados de subsuperfície e os grandes afastamentos aplicados nos levantamentos marítimos tornam a não-hiperbolicidade ainda mais forte. Visando resolver este problema, oito aproximações para realizar a análise de velocidades foram testadas para dois modelos. A análise de complexidade de cada aproximação não-hiperbólica multiparamétrica também foi estudada para entender seus comportamentos durante o processo de otimização. Os erros relativos entre as curvas observadas e calculadas com cada aproximação foram calculados para os eventos de reflexão PP e PS dos dois modelos. Com estas informações, foi possível determinar qual aproximação é a mais confiável para estes tipos de modelos.Palavras-chave: multicomponente, OBN; não-hiperbólico, multiparamétrico.

Reflection seismic imaging of buried shallow salt structures – examples from ongoing case studies in Northern Germany

2021 ◽  
Author(s):  
Ulrich Polom ◽  
Rebekka Mecking ◽  
Phillip Leineweber ◽  
Andreas Omlin
Keyword(s):  
High Resolution ◽  
Water Resources ◽  
Industrial Development ◽  
Geophysical Methods ◽  
Hydrocarbon Exploration ◽  
P Wave ◽  
Depth Range ◽  
Reflection Seismic ◽  
Wide Range ◽  
Cap Rock

<p>In the North German Basin salt tectonics generated a wide range of evaporite structures since the Upper Triassic, resulting in e.g. extended salt walls, salt diapirs, and salt pillows in the depth range up to 8 km. Due to their trap and seal properties these structures were in the focus of hydrocarbon exploration over many decades, leading to an excellent mapping of their geometries below 300 m in depth. During salt rise Rotliegend formations were partly involved as a constituent. Some structures penetrated the salt table, some also the former surface. Dissolution (subrosion) and erosion of the salt cap rock by meteoric water took place, combined with several glacial and intraglacial overprints. Finally the salt structures were covered by pleistocene and holocene sediments. This situation partly resulted in proneness for ongoing karstification of the salt cap rock, leading to e.g. local subsidence and sinkhole occurrence at the surface. The geometry, structure and internal lithology of these shallow salt cap rocks are widely unknown. Expanding urban and industrial development, water resources management and increasing climate change effects enhance the demands for shallow mapping and characterization of these structures regarding save building grounds and sustainable water resources.</p><p>Results of shallow drilling investigations of the salt cap rock and the overburden show unexpectedly heterogenous subsurface conditions, yielding to limited success towards mapping and characterization. Thus, shallow high-resolution geophysical methods are in demand to close the gaps with preferred focus of applicability in urban and industrial environments. Method evaluations starting in 2010 geared towards shallow high-resolution reflection seismic to meet the requirements of both depth penetration and structure resolution. Since 2017 a combination of S-wave and P-wave seismic methods including depth calibrations by Vertical Seismic Profiling (VSP) enabled 2.5D subsurface imaging starting few meters below the surface up to several hundred meters depth in 0.5-5 m resolution range, respectively. The resulting profiles image strong variations along the boundaries and on top of the salt cap rock. Beside improved mapping capabilities, aim of research is the development of characteristic data features to differentiate save and non-save areas.</p>

scholarly journals A Numerical Study on Travel Time Based Hydraulic Tomography Using the SIRT Algorithm with Cimmino Iteration

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 909 ◽  
Author(s):  
Pengxiang Qiu ◽  
Rui Hu ◽  
Linwei Hu ◽  
Quan Liu ◽  
Yixuan Xing ◽  
...  
Keyword(s):  
Travel Time ◽  
Numerical Study ◽  
Correlation Coefficients ◽  
Structural Similarity ◽  
Iteration Step ◽  
Reconstruction Technique ◽  
Hydraulic Tomography ◽  
Iterative Reconstruction Technique ◽  
The Stability ◽  
Mean Square Errors

Travel time based hydraulic tomography is a technique for reconstructing the spatial distribution of aquifer hydraulic properties (e.g., hydraulic diffusivity). Simultaneous Iterative Reconstruction Technique (SIRT) is a widely used algorithm for travel time related inversions. Due to the drawbacks of SIRT implementation in practice, a modified SIRT with Cimmino iteration (SIRT-Cimmino) is proposed in this study. The incremental correction is adjusted, and an iteration-dependent relaxation parameter is introduced. These two modifications enable an appropriate speed of convergence, and the stability of the inversion process. Furthermore, a new result selection rule is suggested to determine the optimal iteration step and its corresponding result. SIRT-Cimmino and SIRT are implemented and verified by using two numerical aquifer models with different predefined (“true”) diffusivity distributions, where high diffusivity zones are embedded in a homogenous low diffusivity field. Visual comparison of the reconstructions shows that the reconstruction based on SIRT-Cimmino demonstrates the aquifer’s hydraulic features better than the conventional SIRT algorithm. Root mean square errors and correlation coefficients are also used to quantitatively evaluate the performance of the inversion. The reconstructions based on SIRT-Cimmino are found to preserve the connectivity of the high diffusivity zones and to provide a higher structural similarity to the “true” distribution.

Comparison of nonhyperbolic travel-time approximations for multicomponent seismic data

2015 ◽  
Author(s):  
Nelson Ricardo Coelho Flores Zuniga* ◽  
Oleg Bokhonok ◽  
Liliana Alcazar Diogo
Keyword(s):  
Travel Time ◽  
Seismic Data ◽  
Multicomponent Seismic

scholarly journals Converted-wave azimuth moveout

Geophysics ◽  
2006 ◽  
Vol 71 (3) ◽  
pp. S99-S110
Author(s):  
Daniel A. Rosales ◽  
Biondo Biondi
Keyword(s):  
Seismic Data ◽  
Extreme Case ◽  
Ocean Bottom ◽  
Sampled Data ◽  
Computationally Efficient ◽  
Converted Wave ◽  
Data Set ◽  
Prestack Migration ◽  
Conversion Point ◽  
The Common

A new partial-prestack migration operator to manipulate multicomponent data, called converted-wave azimuth moveout (PS-AMO), transforms converted-wave prestack data with an arbitrary offset and azimuth to equivalent data with a new offset and azimuth position. This operator is a sequential application of converted-wave dip moveout and its inverse. As expected, PS-AMO reduces to the known expression of AMO for the extreme case when the P velocity is the same as the S velocity. Moreover, PS-AMO preserves the resolution of dipping events and internally applies a correction for the lateral shift between the common-midpoint and the common-reflection/conversion point. An implementation of PS-AMO in the log-stretch frequency-wavenumber domain is computationally efficient. The main applications for the PS-AMO operator are geometry regularization, data-reduction through partial stacking, and interpolation of unevenly sampled data. We test our PS-AMO operator by solving 3D acquisition geometry-regularization problems for multicomponent, ocean-bottom seismic data. The geometry-regularization problem is defined as a regularized least-squares-objective function. To preserve the resolution of dipping events, the regularization term uses the PS-AMO operator. Application of this methodology on a portion of the Alba 3D, multicomponent, ocean-bottom seismic data set shows that we can satisfactorily obtain an interpolated data set that honors the physics of converted waves.

Travel-time residuals of teleseismic P-waves at the Rodriguez Triple Junction in the Indian Ocean using ocean-bottom seismometers

1996 ◽  
Vol 23 (7) ◽  
pp. 713-716 ◽  
Author(s):  
Toshinori Sato ◽  
Kei Katsumata ◽  
Junzo Kasahara ◽  
Naoshi Hirata ◽  
Ryota Hino ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Travel Time ◽  
Triple Junction ◽  
Ocean Bottom ◽  
P Waves ◽  
Ocean Bottom Seismometers ◽  
The Indian Ocean

scholarly journals Contourite vs Turbidite Outcrop and Seismic Architectures

2020 ◽  
Vol 1 (1) ◽  
pp. 20-26
Author(s):  
Cirilo Cauxeiro ◽  
Michel Lopez ◽  
Javier Hernández-Molina ◽  
Artur Miguel ◽  
Gizela Cauxeiro ◽  
...  
Keyword(s):  
Spatial Association ◽  
Hydrocarbon Exploration ◽  
Bottom Current ◽  
Economic Implication ◽  
Oil Companies ◽  
Petroleum Systems ◽  
Reflection Seismic ◽  
Stratigraphic Architecture ◽  
Definition Of ◽  
Sandy Contourites

The hydrocarbon exploration of oceanic depositional systems demands a better understanding of the role of bottom currents and their implications for petroleum systems such as reservoir and sealing rocks. Deep-marine bottom-current reworked sands (sandy contourites) have been recognized in hydrocarbon-bearing sands of the Kwanza Basin. Such understanding implies additional alternatives for the definition of exploration targets and prospect risk reduction. The southernmost part of the Kwanza Basin (Miradouro da Lua zone) comprises one of the best outcrops of contourites deposits, formed during the Miocene and Pliocene age. Laterally, coeval sandy deposits are found offshore Kwanza Basin along the continental margin, and have been one of the great challenges for the oil companies operating in Angola. Therefore, the aim of the current proposal is to characterize sandy contourite deposits at Miradouro da Lua and compare them with offshore deep-water sandy deposits, evaluating their conceptual and economic implication. Modern field sedimentology technique merged with reflection seismic data and other geographic information system (GIS) techniques, allow the characterization and proposal of a stratigraphic architecture diagram that explains the interaction of the deep-marine processes, especially gravitational (down-slope) and bottom current (along-slope) processes as well as its vertical and spatial association. Sonangol (Angolan State Oil Company) and Total (French Multinational Company) explore similar deposits in Block 48 in Ultra deep-sea, and they will also reactivate the exploration of the Iabe Formation in Block 4.  The Tertiary Stratigraphic Architecture in Blocks 6, 7, 8, 19 and 20 are similar to the Lower part of the Miradouro da Lua zone. All these observations and data are very important to calibrate oil reservoir models.

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