Podcast
Questions and Answers
What has led to a revision of the industry's attitude towards anisotropy?
What has led to a revision of the industry's attitude towards anisotropy?
Which type of anisotropy is usually considered in reservoir studies?
Which type of anisotropy is usually considered in reservoir studies?
What is the most striking example of HTI anisotropy in reservoir studies?
What is the most striking example of HTI anisotropy in reservoir studies?
How are smaller fractures with sub-seismic lengths that cannot be directly imaged usually inferred from seismic data?
How are smaller fractures with sub-seismic lengths that cannot be directly imaged usually inferred from seismic data?
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Which method is used to describe the reservoir in advanced QI techniques?
Which method is used to describe the reservoir in advanced QI techniques?
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What is one of the techniques introduced in this module according to the text?
What is one of the techniques introduced in this module according to the text?
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What does the use of azimuthal AVO analysis help predict?
What does the use of azimuthal AVO analysis help predict?
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How does increasing the frequency content to the higher end of the spectrum affect the seismic signal?
How does increasing the frequency content to the higher end of the spectrum affect the seismic signal?
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What is one advantage of including anisotropy information in a reservoir model?
What is one advantage of including anisotropy information in a reservoir model?
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What is one benefit of variable-depth streamer acquisition over conventional streamer profiles?
What is one benefit of variable-depth streamer acquisition over conventional streamer profiles?
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Why are low frequencies often absent in conventional seismic data?
Why are low frequencies often absent in conventional seismic data?
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What characterizes the interface property in anisotropic gradient analysis?
What characterizes the interface property in anisotropic gradient analysis?
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In seismic reservoir characterization, why is broadband seismic data particularly valuable?
In seismic reservoir characterization, why is broadband seismic data particularly valuable?
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What helps validate the results obtained from different azimuthal approaches in seismic analysis?
What helps validate the results obtained from different azimuthal approaches in seismic analysis?
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"Frequency, in addition to amplitudes, provides valuable information". What does increasing frequency range at the lower end minimize?
"Frequency, in addition to amplitudes, provides valuable information". What does increasing frequency range at the lower end minimize?
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How does extending frequency range at the lower end help address challenges related to sidelobes in seismic data?
How does extending frequency range at the lower end help address challenges related to sidelobes in seismic data?
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What geomechanical parameters can be inferred by analyzing seismic anisotropy?
What geomechanical parameters can be inferred by analyzing seismic anisotropy?
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In seismic studies, HTI anisotropy is usually associated with:
In seismic studies, HTI anisotropy is usually associated with:
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Why do seismic wave velocities vary with direction in the presence of aligned vertical fractures?
Why do seismic wave velocities vary with direction in the presence of aligned vertical fractures?
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What does Azimuthal Velocity Analysis help define in seismic studies?
What does Azimuthal Velocity Analysis help define in seismic studies?
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How does Azimuthal AVO analysis differ from conventional AVO analysis?
How does Azimuthal AVO analysis differ from conventional AVO analysis?
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What can be inferred from velocity inconsistencies between isotropic inversion and azimuthal inversion measurements?
What can be inferred from velocity inconsistencies between isotropic inversion and azimuthal inversion measurements?
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Why has the industry's attitude towards studying seismic anisotropy changed over time?
Why has the industry's attitude towards studying seismic anisotropy changed over time?
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What is the primary difference between PP and PS waves in terms of velocity?
What is the primary difference between PP and PS waves in terms of velocity?
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Which type of seismic wave typically exhibits higher frequencies?
Which type of seismic wave typically exhibits higher frequencies?
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Why is it important to align or register PS seismic to PP seismic prior to inversion?
Why is it important to align or register PS seismic to PP seismic prior to inversion?
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What is the main advantage of utilizing 4D seismic data in reservoir characterization?
What is the main advantage of utilizing 4D seismic data in reservoir characterization?
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What does joint inversion of PP-PS data enable in terms of model constraining?
What does joint inversion of PP-PS data enable in terms of model constraining?
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How do azimuthal seismic data contribute to reservoir management?
How do azimuthal seismic data contribute to reservoir management?
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In seismic inversion, why is the presence of low-frequency data in broadband datasets important?
In seismic inversion, why is the presence of low-frequency data in broadband datasets important?
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What is one of the key benefits of using PS data in seismic studies?
What is one of the key benefits of using PS data in seismic studies?
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What role does mode conversion play in seismic studies?
What role does mode conversion play in seismic studies?
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How does broadband seismic data differ from conventional seismic data?
How does broadband seismic data differ from conventional seismic data?
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What is the significance of studying PP data for gaining insights into S-wave velocity?
What is the significance of studying PP data for gaining insights into S-wave velocity?
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Why are PS waves preferred over PP waves for studying subsurface beneath gas clouds?
Why are PS waves preferred over PP waves for studying subsurface beneath gas clouds?
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What is the primary advantage of joint PP-PS tomography?
What is the primary advantage of joint PP-PS tomography?
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Why is the presence of low-frequency reflectivity crucial for inversion algorithms?
Why is the presence of low-frequency reflectivity crucial for inversion algorithms?
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What effect does mode conversion have on seismic signal interference?
What effect does mode conversion have on seismic signal interference?
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What geomechanical parameters can be inferred by analyzing seismic anisotropy?
What geomechanical parameters can be inferred by analyzing seismic anisotropy?
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How do seismic wave velocities typically vary in the presence of aligned vertical fractures?
How do seismic wave velocities typically vary in the presence of aligned vertical fractures?
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What insight can be gained from studying variations in velocity or amplitude as functions of azimuth?
What insight can be gained from studying variations in velocity or amplitude as functions of azimuth?
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What challenges are associated with conducting repeat 4D seismic surveys for reservoir monitoring?
What challenges are associated with conducting repeat 4D seismic surveys for reservoir monitoring?
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How can changes in fluid saturation affect the elastic properties of rocks in a reservoir?
How can changes in fluid saturation affect the elastic properties of rocks in a reservoir?
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What information does a significant improvement in correspondence between P-wave velocities obtained indicate?
What information does a significant improvement in correspondence between P-wave velocities obtained indicate?
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Why can comparing Vp obtained from isotropic inversion with Vp measured in a horizontal well reveal inconsistencies?
Why can comparing Vp obtained from isotropic inversion with Vp measured in a horizontal well reveal inconsistencies?
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What is the primary challenge of integrating time-lapse seismic data with other reservoir data?
What is the primary challenge of integrating time-lapse seismic data with other reservoir data?
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What do changes in the fluid saturation, pressure, porosity, and temperature of a reservoir result in?
What do changes in the fluid saturation, pressure, porosity, and temperature of a reservoir result in?
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Why is it essential to ensure consistency in acquisition parameters and data quality between baseline and repeat surveys in 4D seismic monitoring?
Why is it essential to ensure consistency in acquisition parameters and data quality between baseline and repeat surveys in 4D seismic monitoring?
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Study Notes
Advanced QI Methods
- Introduce 4D reservoir characterization, Azimuthal AVO, and Inversion
- Inversion of broadband seismic data and PP-PS joint inversion
Seismic Anisotropy
- Study of seismic anisotropy gained importance since the 1950s
- Effects of anisotropy were initially ignored in production work due to limitations of techniques
- Development of computer technologies and seismic methods led to a revision of the industry's attitude towards anisotropy
- HTI (horizontal transverse isotropy) anisotropy is considered in reservoir studies, often represented as vertical inhomogeneities of an isotropic medium
- Example: vertical fractures
Measuring Seismic Anisotropy
- Measure travel times and amplitudes of waves propagating in various directions
- Study variations in velocity or amplitude as functions of azimuth to gain insights into seismic anisotropy
4D Seismic Reservoir Characterization
- Changes in fluid saturation, pressure, porosity, and temperature of a reservoir result in changes in elastic properties of rocks, affecting the seismic response
- 4D seismic provides valuable insights into reservoir dynamics, essential for optimizing reservoir management and production strategies
- Challenges of 4D seismic: maintaining signal stability, integrating with other reservoir data, and understanding complex relationships between seismic attributes and reservoir properties
- Example: Draugen Field 4D Study, resolving uncertainties and forecasting an extension in plateau production
Azimuthal Velocity Analysis
- Based on the effect of different times of arrival of the reflected wave for different azimuths
- Estimates seismic anisotropy by defining the stacking velocities Vfast and Vslow and direction of Vfast
- Corrects gathers with anisotropic NMO (normal moveout)
Azimuthal AVO Analysis
- Studies amplitude variations with offset, also conducted for different azimuthal directions
- Key results: anisotropic gradient Bani and direction of the plane of isotropy φiso
- Bani is proportional to fracture density, allowing prediction of fracture presence
Inversion of Angle Stacks
- Inverts angle stacks for different azimuths to obtain elastic properties, anisotropy coefficients, and azimuth as layer properties
Validating Results with Wells
- Results of azimuthal approaches should be validated with wells using imaging logs like FMI (formation micro-imager)
- Example: tight but fractured carbonate reservoir with low matrix permeability
Broadband Seismic
- Provides valuable information, filling the low-frequency gap
- Enables capturing of finer details and subtle features within subsurface geology, resulting in higher-resolution seismic images
- Increases the accuracy and robustness of estimates of reservoir properties
- Example: marine acquisition with variable-depth streamer acquisition to access full bandwidth
Joint PP-PS Inversion
- Combines independent information about S-waves, further constraining the model
- Leads to improved accuracy and reliability in the estimation of elastic properties
- Enables enhanced reservoir properties analysis
- Example: successful PP-PS project from offshore Vietnam
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Description
This quiz covers key concepts in rock physics related to fracture characterization and the utilization of azimuthal AVO analysis to predict fractures. It also explores the significance of anisotropic gradient in characterizing interface properties in seismic interpretation.
