A New Approach to Imaging and Pore Pressure Analysis in Depth Domain in Complex Geologic Areas: Use of Rock Physics Constrained Velocity Modeling and Reverse-Time Migration

2015 ◽  
Author(s):  
Nader C. Dutta* ◽  
Sherman Yang ◽  
Yangjun (Kevin) Liu
Keyword(s):  
Pore Pressure ◽  
Rock Physics ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
New Approach ◽  
Velocity Modeling ◽  
Time Migration ◽  
Pressure Analysis

scholarly journals Reverse time migration of multiples for subsalt imaging

Geophysics ◽  
2011 ◽  
Vol 76 (5) ◽  
pp. WB209-WB216 ◽  
Author(s):  
Yike Liu ◽  
Xu Chang ◽  
Degang Jin ◽  
Ruiqing He ◽  
Hongchuan Sun ◽  
...  
Keyword(s):  
Numerical Test ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
Multiple Reflections ◽  
Depth Level ◽  
Data Set ◽  
New Approach ◽  
Time Migration ◽  
Recorded Data ◽  
Subsalt Imaging

Some hydrocarbon reservoirs are trapped beneath salt bodies, where seismic imaging is greatly challenged due to poor illumination. Multiple reflections have different propagation wave paths from primary reflections and thus can be used to complement the illuminations where primary reflections from beneath the salt are not acquired. Consequently, migration of multiples can sometimes provide better subsalt images compared to conventional migration which uses primary reflections only. In this paper, we propose to modify conventional reverse time migration so that multiples can be used as constructive reflection energy for subsalt imaging. This new approach replaces the impulsive source wavelet with the recorded data containing both primaries and multiples and uses predicted multiples as the input data instead of primary reflections. In the reverse time migration process, multiples recorded on the surface are extrapolated backward in time to each depth level, and the observed data with both primaries and multiples are extrapolated forward in time to the same depth levels, followed by a crosscorrelation imaging condition. A numerical test on the Sigsbee2B data set shows that a wider coverage and a more balanced illumination of the subsurface can be achieved by migration of multiples compared with conventional migration of primary reflections. This example demonstrates that reverse time migration of multiples might be a promising method for complex subsalt imaging.

Wide-azimuth TTI imaging at Tahiti: Reducing structural uncertainty of a major deepwater subsalt field

Geophysics ◽  
2011 ◽  
Vol 76 (5) ◽  
pp. WB67-WB78 ◽  
Author(s):  
Alastair M. Swanston ◽  
Michael D. Mathias ◽  
Craig A. Barker
Keyword(s):  
Seismic Data ◽  
Transverse Isotropy ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
Initial Development ◽  
Field Development ◽  
Velocity Modeling ◽  
Multiple Attenuation ◽  
Time Migration ◽  
Seismic Volumes

The Tahiti field is a recent major development in the deepwater Gulf of Mexico. The field’s prolific Miocene reservoir section lies below a thick salt canopy with structural dips as high as 80 degrees, adjacent to a near-vertical salt root. Successful appraisal and initial development was enabled by interpretation of proprietary depth imaging products generated from narrow-azimuth seismic data. However, reservoir-scale mapping and fault definition remained problematic due to seismic imaging and illumination challenges. In 2009–2010, the Tahiti partnership initiated a reimaging project using multiclient wide-azimuth seismic data. The project employed current technologies for multiple attenuation, tilted transverse isotropy velocity modeling, and migration. Increased azimuthal coverage and inherent multiple suppression provided by wide azimuth acquisition delivered significant imaging enhancements. Advanced noise and multiple attenuation techniques provided cleaner data with improved signal-to-noise. Earth models representing multiazimuth subsurface velocities and anisotropy parameters calibrated to well control with detailed salt interpretation resulted in higher confidence structural imaging. Comparison of Gaussian beam, one-way wave equation, and reverse time migration algorithms shows that reverse time migration generally provides superior subsalt and salt-body data quality, with improved event positioning, higher resolution, and enhanced steep dip imaging. The resulting seismic volumes enable accurate mapping of reservoir horizons and faulting. This will improve resource determination and future well placement in the next phase of field development.

Reverse time migration in tilted transversely isotropic media

2020 ◽  
Vol 38 (2) ◽  
Author(s):  
Razec Cezar Sampaio Pinto da Silva Torres ◽  
Leandro Di Bartolo
Keyword(s):  
Seismic Anisotropy ◽  
Synthetic Data ◽  
Transversely Isotropic ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
Computer Clusters ◽  
Time Migration ◽  
Transversely Isotropic Media ◽  
Isotropic Media ◽  
Tti Media

ABSTRACT. Reverse time migration (RTM) is one of the most powerful methods used to generate images of the subsurface. The RTM was proposed in the early 1980s, but only recently it has been routinely used in exploratory projects involving complex geology – Brazilian pre-salt, for example. Because the method uses the two-way wave equation, RTM is able to correctly image any kind of geological environment (simple or complex), including those with anisotropy. On the other hand, RTM is computationally expensive and requires the use of computer clusters. This paper proposes to investigate the influence of anisotropy on seismic imaging through the application of RTM for tilted transversely isotropic (TTI) media in pre-stack synthetic data. This work presents in detail how to implement RTM for TTI media, addressing the main issues and specific details, e.g., the computational resources required. A couple of simple models results are presented, including the application to a BP TTI 2007 benchmark model.Keywords: finite differences, wave numerical modeling, seismic anisotropy. Migração reversa no tempo em meios transversalmente isotrópicos inclinadosRESUMO. A migração reversa no tempo (RTM) é um dos mais poderosos métodos utilizados para gerar imagens da subsuperfície. A RTM foi proposta no início da década de 80, mas apenas recentemente tem sido rotineiramente utilizada em projetos exploratórios envolvendo geologia complexa, em especial no pré-sal brasileiro. Por ser um método que utiliza a equação completa da onda, qualquer configuração do meio geológico pode ser corretamente tratada, em especial na presença de anisotropia. Por outro lado, a RTM é dispendiosa computacionalmente e requer o uso de clusters de computadores por parte da indústria. Este artigo apresenta em detalhes uma implementação da RTM para meios transversalmente isotrópicos inclinados (TTI), abordando as principais dificuldades na sua implementação, além dos recursos computacionais exigidos. O algoritmo desenvolvido é aplicado a casos simples e a um benchmark padrão, conhecido como BP TTI 2007.Palavras-chave: diferenças finitas, modelagem numérica de ondas, anisotropia sísmica.

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