Proposed Workflow to Incorporate Stratification within Salt Section Using Velocity and Seismic Attributes

González, María; Gobatto, Fernanda; Maul, Alexandre; Falcão, Livia; González, Gaspar; Oliveira, Luiz Carlos Veiga de; Meneguim, Talles Barsanti; Amaral, Pedro Jonas Teixeira

doi:10.3997/2214-4609.201600050

Cited by 17 publications

(17 citation statements)

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“…Competent layers encased within a weak, ductile matrix undergo boudinage during layer-parallel extension (e.g., Ramberg, 1955;Ramsay, 1967;Goscombe et al, 2004). With enough extension, the strong layers separate into distinct boudins, with the ductile material flowing into the space created.…”

Section: Extensionmentioning

confidence: 99%

“…As mentioned briefly above, the competency contrast between relatively strong layers and weak halite and bittern salts influences the style of deformation. In extension, if the competency contrast between the strong layer and its more ductile matrix is relatively small, pinch-and-swell structures (or drawn boudins) develop; if it is relatively large, the strong layer extends by brittle fracturing and forms torn boudins (e.g., Ramberg, 1955;Ramsay, 1967;Goscombe et al, 2004;Abe and Urai, 2012). The large contrasts within LES result in predominantly torn boudins (Figs.…”

Section: Thickness and Strengthmentioning

confidence: 99%

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Deformation of intrasalt competent layers in different modes of salt tectonics

Rowan

Urai

Fiduk³

et al. 2019

Solid Earth

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Abstract. Layered evaporite sequences (LESs) comprise interbedded weak layers (halite and, commonly, bittern salts) and strong layers (anhydrite and usually non-evaporite rocks such as carbonates and siliciclastics). This results in a strong rheological stratification, with a range of effective viscosity up to a factor of 105. We focus here on the deformation of competent intrasalt beds in different endmember modes of salt tectonics, even though combinations are common in nature, using a combination of conceptual, numerical, and analog models, and seismic data. In bedding-parallel extension, boudinage of the strong layers forms ruptured stringers, within a halite matrix, that become more isolated with increasing strain. In bedding-parallel shortening, competent layers tend to maintain coherency while forming harmonic, disharmonic, and polyharmonic folds, with the rheological stratification leading to buckling and fold growth by bedding-parallel shear. In differential loading, extension and the resultant stringers dominate beneath suprasalt depocenters, while folded competent beds characterize salt pillows. Finally, in passive diapirs, stringers generated by intrasalt extension are rotated to near vertical and encased in complex folds during upward flow of salt. In all cases, strong layers are progressively removed from areas of salt thinning and increasingly disrupted and folded in areas of salt growth as deformation intensifies. The varying styles of intrasalt deformation impact seismic imaging of LES and associated interpretations. Ruptured stringers are often visible where they have low dips, as in slightly extended salt layers or beneath depocenters, but are poorly imaged in passive diapirs due to steep dips. In contrast, areas of slightly to moderately shortened salt typically have well-imaged, mostly continuous intrasalt reflectors, although seismic coherency decreases as deformation intensifies. Similarly, wells are most likely to penetrate strong layers in contractional structures and salt pillows, less likely in extended salt because they might drill between stringers, and unlikely in tall passive diapirs because the stringers are near vertical. Thus, both seismic and well data may be interpreted to suggest that diapirs and other areas of more intense intrasalt deformation are more halite rich than is actually the case.

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Section: Extensionmentioning

confidence: 99%

Section: Thickness and Strengthmentioning

confidence: 99%

Deformation of intrasalt competent layers in different modes of salt tectonics

Rowan

Urai

Fiduk³

et al. 2019

Solid Earth

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“…The first part of the methodology applied in this project follows the workflow presented in González et al (2016), see Figure 1. This method allows the insertion of the salt stratifications or the layered sequence using seismic acoustic inversion (as presented by Meneguim et al, 2015), or any other seismic attribute if the inversion output is not available.…”

Section: Methodsmentioning

confidence: 99%

“…During the methodology development, several applications have taken advantage of using this strategy of modeling evaporitic stratifications. The more promising applications are related to uncertainties Jardim et al, 2015), geomechanics (Toríbio et al, 2017;Teixeira et al, 2018), Kirchhoff migration and Reverse Time Migration -RTM (Gobatto et al, 2016;Fonseca et al, 2018;Maul et al, 2018a) and the initial model for Least-Square Migration (Dias et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Improving Pre-Salt Reservoirs Seismic Images When Considering the Stratified Evaporites Insertion in the Initial Model for the Velocity Updating Processes Prior to the Seismic Migration

Maul¹,

Santos²,

Silva³

et al. 2019

Braz J Geophys

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ABSTRACT. Structurally complex areas, such as the pre-salt section in the offshore Santos Basin, SE Brazil, is a challenge to represent the geology using seismic images. One of the main causes of the observed imaging problems is the evaporitic section and its considerations about velocities used for seismic migration purposes. Some authors consider set to this section an almost constant value (close to 4,500 m/s) which approximately represents the halite velocity, the most abundant mineral in this salt formation. Others, over these models, apply the tomographic inversion or FWI schemes giving to the velocity model the mathematical support to build confident seismic images. We believe in the importance to build starting velocity models reflecting the existing geological features prior to applying the tomographic/FWI updating. In this sense, we propose the insertion of the so-called stratifications within the evaporitic section using an adaptation of the model-based seismic inversion technique. Following this new velocity model including the stratification, we suggest tomographic iterations update, or FWI, to add to the geological constrains of the model the needed mathematical convergence. Finally, in this work, we performed the seismic migration with and without inserting these geological features in the initial velocity model and compared the results.Keywords: evaporitic section, stratifications, velocity model, seismic migration, seismic image.RESUMO. Em áreas estruturalmente complexas, como na seção pré-sal da Bacia offshore de Santos, região SE do Brasil, é um desafio representar a geologia utilizando imagens sísmicas. Uma das principais causas dos problemas observados está nas considerações sobre a seção evaporítica e suas velocidades com propósito de migração sísmica. Alguns autores consideram esta seção como tendo velocidades aproximadamente constantes (próximas de 4.500 m/s), o que representa aproximadamente o comportamento da halita, o mineral mais abundante nesta seção. Outros, sobre este modelo aplicam a atualização por inversão tomográfica ou FWI para dar ao modelo de velocidades o suporte matemático necessário para construir imagens sísmicas confiáveis. Nós acreditamos na importância de construir modelos iniciais de velocidades que reflitam as características geológicas existentes antes de aplicar esta atualização tomográfica/FWI mencionada. Neste sentido, propomos a inserção das denominadas estratificações dentro da seção evaporítica, utilizando uma adaptação da técnica de inversão sísmica model-based. Seguindo este novo modelo incluindo as estratificações, sugerimos a atualização por iterações tomográficas, ou FWI, para adicionar ao controle geológico do modelo a convergência matemática necessária. Finalmente, neste trabalho, nós realizamos a migração com e sem a inserção destas características geológicas no modelo inicial de velocidades e comparamos os resultados.Palavras-chave: seção evaporítica, estratificações, modelo de velocidade, migração sísmica, imagem sísmica.

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“…Using these mentioned approaches, many authors have presented ways, to include the existing stratifications within the evaporitic section, trying to better represent its heterogeneity: Maul et al (2015,2016), Borges et al (2015), Jardim et al (2015), Meneguim et al (2015,2016), Oliveira et al (2015), González et al (2016) and Yamamoto et al (2016. These authors based their approaches on seismic attributes as amplitude, relative acoustic impedance, absolute impedance, seismic facies analysis, etc.…”

Section: Introductionmentioning

confidence: 99%

Results of Incorporating the Stratigraphy Within the Evaporitic Sequence Into the Velocity Field for Reservoir Characterization

Falcão¹,

Maul²,

Gobatto³

et al. 2016

Rev. Bras. Geof.

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ABSTRACT. There are many ways to build velocity models for seismic migration purposes, either by using inversion algorithms, approximations by constant or variables velocities, including or not including anisotropic parameters, etc...Keywords: amplitude responses, attributes, salt, pre-salt, uncertainties. RESUMO. Atualmente existem muitas alternativas para construção de modelos de velocidades para propósitos de migração sísmica, seja usando algoritmos de inversão ou aproximações por estimativas de velocidades constantes e/ou variáveis, inserindo ou não parâmetros de anisotropia, etc.Palavras-chave: respostas de amplitude, atributos, sal, pré-sal, incertezas.

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Proposed Workflow to Incorporate Stratification within Salt Section Using Velocity and Seismic Attributes

Cited by 17 publications

References 0 publications

Deformation of intrasalt competent layers in different modes of salt tectonics

Deformation of intrasalt competent layers in different modes of salt tectonics

Improving Pre-Salt Reservoirs Seismic Images When Considering the Stratified Evaporites Insertion in the Initial Model for the Velocity Updating Processes Prior to the Seismic Migration

Results of Incorporating the Stratigraphy Within the Evaporitic Sequence Into the Velocity Field for Reservoir Characterization

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