Characterizing Evaporitic Section and Geomechanical Properties Using Seismic Inversion, a Case Study for Santos Basin

Toríbio, Thiago; Queiroz, Luiz Eduardo; Teixeira, Leonardo; Yamamoto, T.; Meneguim, Talles Barsanti; Leonardi, O.; Cortez, M.M.M.; Relvas, Maria Taryn; Moliterno, Ana; Tartarini, Antonio Mauricio Nabuco; Fonseca, Josué; Maul, Alexandre

doi:10.1190/sbgf2017-226

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…Following these considerations, Meneguim et al (2015) demonstrated that the inversion study is more likely to deliver good salt velocity models than the simple amplitude approach firstly presented by Maul et al (2015). Several other authors have explored the adaptive inversion concepts from the reservoir scale to the salt section scale (Gobatto et al, 2016;Toríbio et al, 2017;Teixeira et al, 2018;Fonseca et al, 2018). Barros et al (2017) introduced the idea of generating pseudo-logs to fill log gaps, using the approach stablished by Amaral et al (2015), who relied on cutting samples (mud-logs) collected during the well drilling phase.…”

Section: Introductionmentioning

confidence: 99%

Geological Characterization of Evaporitic Sections and Its Impacts on Seismic Images: Santos Basin, Offshore Brazil

Maul¹,

Santos²,

Silva³

et al. 2019

Braz J Geophys

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ABSTRACT. The pre-salt reservoirs in Santos Basin are known for being overlaid by thick evaporitic layers, which degrade the quality of seismic imaging and, hence, impacts reservoir studies. Better seismic characterization of this section can then improve decision making in E&P (Exploration and Production) projects. Seismic inversion - particularly with adequate low-frequency initial models – is currently the best approach to build good velocity models, leading to increased seismic resolution, more reliable amplitude response, and to attributes that can be quantitatively connected to well data. We discuss here a few considerations about inverting seismic data for the evaporitic section, and address procedures to improve reservoir characterization when using this methodology. The results show that we can obtain more realistic seismic images, better predicting both the reservoir positioning and its amplitude. Keywords: evaporitic section, seismic imaging, seismic inversion, reservoir characterization, seismic resolution.RESUMO. Os reservatórios do pré-sal da Bacia de Santos são conhecidos por estarem abaixo de uma espessa camada de evaporitos, que degradam a qualidade das imagens sísmicas e impactam os estudos de reservatórios. Melhores caracterizações desta seção podem, então, melhorar o processo de tomada de decisão em projetos de E&P (Exploração e Produção). Inversão sísmica – particularmente com modelos de baixa frequência inicial adequados – é correntemente a melhor abordagem para se construir modelos de velocidades, auxiliando no aumento de resolução sísmica, obtendo-se respostas de amplitude mais coerentes, e tendo seus atributos quantitativamente conectados com as informações de dados de poços. Aqui discutiremos algumas considerações sobre inversões sísmicas para seção evaporítica, e indicaremos procedimentos para melhorar a caracterização de reservatórios quando utilizando esta metodologia. Os resultados mostram que podemos obter imagens sísmicas mais realistas, com melhores predições tanto em termos de posicionamento quanto de sua amplitude.Palavras-chave: seção evaporítica, imagem sísmica, inversão sísmica, caracterização de reservatórios, resolução sísmica.

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Section: Introductionmentioning

confidence: 99%

Geological Characterization of Evaporitic Sections and Its Impacts on Seismic Images: Santos Basin, Offshore Brazil

Maul¹,

Santos²,

Silva³

et al. 2019

Braz J Geophys

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“…7C). The importance of considering the model-based inversion approach to better establish the stratification is well exemplified and documented in several works (Meneguim et al, 2015;Teixeira et al, 2017;Toríbio et al, 2017;Barros et al, 2017Teixeira et al, 2018;Maul et al, 2019aMaul et al, , 2019bTeixeira & Lupinacci, 2019).…”

Section: Results Analysis and Discussionmentioning

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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The impact of heterogeneous salt velocity models on the gross rock volume estimation: an example from the Santos Basin pre-salt, Brazil

Maul

Cetale

Guizan

et al. 2021

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The thick and heterogeneous salt section in the Santos Basin, offshore Brazil, imposes great challenges to access the pre-salt hydrocarbon reservoirs, especially in relation to seismic imaging, signal quality, and depth positioning. Some problems arise from the current velocity models for the salt section, which for the majority, assume the salt is a homogeneous halite layer. In the Santos Basin, the commonly assumed salt - halite - only makes up to 80% of the mineral in this section. The inclusion of other salts as stratification in the velocity models, based on seismic attributes, has achieved good results in the last decade, especially for depth resolution. In this work, we analyze the benefits of different velocity models, considering presence/absence of salt stratification, and comparing the gross rock volume above the oil-water contact. The results show a significant effect on depth resolution of the events, as well as on volume estimation, indicating that more reliability captured by the complex velocity models will ensure the more confident the resulting volumetric information is.

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Characterizing Evaporitic Section and Geomechanical Properties Using Seismic Inversion, a Case Study for Santos Basin

Cited by 5 publications

References 10 publications

Geological Characterization of Evaporitic Sections and Its Impacts on Seismic Images: Santos Basin, Offshore Brazil

Geological Characterization of Evaporitic Sections and Its Impacts on Seismic Images: Santos Basin, Offshore 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

The impact of heterogeneous salt velocity models on the gross rock volume estimation: an example from the Santos Basin pre-salt, Brazil

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