Salt Stratification and Least Square Migration to Improve Pre-Salt Reservoir Images: Santos Basin, Brazilian Offshore Example

Dias, Roberto de Melo; Fonseca, Josué; Bulcão, André; Dias, Bruno Digo Valença Gomes; Teixeira, Leonardo; Maul, Alexandre; Borges, Filipe

doi:10.3997/2214-4609.201900051

Cited by 4 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We can also note that when we add the detailed velocity model (with the stratification insertion) the results are even better. This last statement confirms that least-squares schemes in the velocity models associated with detailed velocity models has potential to deliver more accurate amplitude responses for the pre-salt targets in the Santos Basin, as pointed in some previous works (Ji et al, 2011;Wang et al, 2017;Fonseca et al, 2018;Dias et al, 2019;Shadrina et al, 2020).…”

Section: Figure 3 -Frequency Content Of the Five Built Images Includi...supporting

confidence: 87%

Analysis of Salt Stratification Modeling Influences over Reverse Time Migration Considering and not Considering Least-Squares Schemes

Maul¹,

Dias²,

Silva³

et al. 2021

Proceeding of the 17th International Congress of the Brazilian Geophysical

View full text Add to dashboard Cite

show abstract

Section: Figure 3 -Frequency Content Of the Five Built Images Includi...supporting

confidence: 87%

Analysis of Salt Stratification Modeling Influences over Reverse Time Migration Considering and not Considering Least-Squares Schemes

Maul¹,

Dias²,

Silva³

et al. 2021

Proceeding of the 17th International Congress of the Brazilian Geophysical

View full text Add to dashboard Cite

show abstract

“…The methodology presented in this work results in an improved initial velocity model for seismic tomography, lowering the computational efforts when compared to the conventional approach ("salt flooding" + inversion tomographic updates), as cited by ), Falcão (2017), Maul et al (2018a), Dias et al (2019 and Maul et al (2019).…”

Section: Discussionmentioning

confidence: 99%

“…These groups are: (i) the Low Velocity Salts/Evaporites group (LVS), mainly composed by carnallite, tachyhydrite, sylvite and other mobile salts; which present compressional velocities lower than the represented by the halite mineral (4,500 m/s); (ii) the Halite group, usually abundant and considered as the background group; represented by the compressional velocity of about 4,500 m/s; and (iii) the High Velocity Salts/Evaporites group (HVS), basically composed by anhydrite and gypsum, having compressional velocities higher than 4,500 m/s. Intrusive rocks, when found, due to the same velocity behavior as HVS minerals, were also considered inside this group -an approach that has been adopted in many case studies (Meneguim et al, 2015;González et al, 2016;Falcão et al, 2016;Barros et al, 2017;Fonseca et al, 2017Fonseca et al, , 2018Teixeira et al, 2018;Maul et al, 2018aMaul et al, ,b, 2019Dias et al, 2019). Fonseca et al (2017) also observed carbonate and siliciclastic occurrences within the salt section, and suggested to group them within the Halite group, as their velocity behaviors are more similar to this background's group.…”

Section: Introductionmentioning

confidence: 99%

“…Even in regions where well data are available, well-logs within the salt section are almost always incomplete, since evaporites are not the main target, and acquiring data in these sections is operationally challenging. To overcome this problem, Amaral et al (2015) proposed to complete the well information with the described lithology from drill cuttings, a methodology that has been widely reproduced since then Barros et al, 2017;González et al, 2018;Cornelius & Castagna, 2018;Fonseca et al, 2018;Teixeira et al, 2018;Maul et al, 2018aMaul et al, ,b, 2019Dias et al, 2019). Maul et al, 2016.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaporitic Velocity Modeling Uncertainties and Variabilities: Implications for Pre-Salt Projects in the Santos Basin, Brazil

Maul¹,

Santos²,

Silva³

et al. 2019

Braz J Geophys

View full text Add to dashboard Cite

Correct representation of the spatial distribution of physical and chemical properties of the evaporitic section is of great importance for development of pre-salt section reservoirs. In the Santos Basin, offshore Brazil, an increasing amount of high quality seismic, well-logs, and production data are available. The initial conceptual model of the evaporitic section, assuming inhomogeneous behaviors in terms of mineral composition, acoustic and elastic properties, had not been well documented yet. Therefore, this interval remains considered as mainly composed by halite, being slightly modified to include a few heterogeneities when needed. A simple way to represent those heterogeneities is by combining seismic attributes and well-log information, which are usually not available for the whole evaporitic section. To mitigate this problem, drill cuttings description could be used. In this paper, we describe some of the uncertainties related to the analysis of 1D information from wells, as well as a possible alternative to represent the data variability where information is missing. The proposed methodology includes generating a detailed evaporitic section model (3D), regarding properties and their related uncertainties. This model can be used to improve seismic imaging, depth positioning forecast and reservoir property values distribution.Keywords: evaporitic section, data analysis, heterogeneities, property value, uncertainties. RESUMORepresentar corretamente a distribuição espacial das propriedades físicas e químicas da seção evaporítica é muito importante no desenvolvimento dos reservatórios do pré-sal. Na Bacia de Santos, offshore Brasil, grande quantidade de dados sísmicos de alta qualidade, perfis de poço, dados de produção estão disponíveis. O modelo conceitual desta seção, assumindo o mesmo como não homogêneo, em termos de mineralogia e propriedades acústicas e elásticas, ainda não é bem documentado. Assim, este intervalo permanece sendo considerado como, principalmente, composto por halita e, localmente, modificado para incluir algumas heterogeneidades, quando necessário. Um caminho simples para representar estas heterogeneidades é combinar atributos sísmicos e informações dos perfis de poços que, usualmente, não estão disponíveis para toda a seção. Para mitigar este problema, descrição de amostras de calhas pode ser utilizada. Neste artigo, nós descreveremos algumas das incertezas relacionadas à esta análise 1D, oriundas das informações dos poços, assim como uma possível alternativa para representar as variabilidades destes dados inexistentes. A metodologia proposta inclui a geração de um modelo (3D) detalhado da seção evaporítica, observando suas propriedades e as incertezas relacionadas. Este modelo pode ser utilizado para melhorar as imagens sísmicas, melhores previsões de profundidades, e distribuição de valores de propriedades de reservatórios.Palavras-chave: seção evaporítica, análise de dados, heterogeneidades, valores de propriedades, incertezas.

show abstract

“…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

View full text Add to dashboard Cite

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.

show abstract

Salt Stratification and Least Square Migration to Improve Pre-Salt Reservoir Images: Santos Basin, Brazilian Offshore Example

Cited by 4 publications

References 0 publications

Analysis of Salt Stratification Modeling Influences over Reverse Time Migration Considering and not Considering Least-Squares Schemes

Analysis of Salt Stratification Modeling Influences over Reverse Time Migration Considering and not Considering Least-Squares Schemes

Evaporitic Velocity Modeling Uncertainties and Variabilities: Implications for Pre-Salt Projects in the Santos Basin, Brazil

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

Contact Info

Product

Resources

About