Petroleum Geophysics Short Courses
- 3-D Seismic Interpretation
- Application & Interpretation of Converted Waves
- CSEM & MT Methods
- Electromagnetic & Potential Field Methods
- Fundamentals of Geophysical Data Processing
- Geophysical Data Processing
- Microseismic Imaging & Interpretation
- Practical Marine Electromagnetic Methods
- Reservoir Geophysics
- Rock & Fluid Physics
- Seismic Attributes for Carbonate Reservoirs
- Seismic Migration
- Seismic Wave & Ray Theory
3-D Seismic Interpretation
Fundamental concepts and foundations of wave and ray theory necessary for seismic processing, imaging, AVO analysis and structural interpretation.
- Review of rock properties, wave, and ray theory
- Reservoir properties and well-log measurements
- Seismic amplitude variation as a function of offset
- Principles of fluid substitution
- Parameterization of the AVO response for fluid product estimation
- Recognition of hydrocarbon signatures and interpretive "rules-of-thumb"
- AVO inversion for rock-properties, impedances and reflectivities
- The information content & complications in long offset and post critical data
- Fizz gas, anisotropy, and other challenges facing the exploration industry
All rock masses are seismically anisotropic, but we generally ignore this in our seismic acquisition, processing, and interpretation. The anisotropy nonetheless does effect our data, in ways that limit the effectiveness with which we can use it, if we ignore this basic fact. This course helps us understand why this inconsistency between reality and practice has been so pervasive in the past and why it will be less successful in the future, as we acquire modern seismic data (especially including wide-azimuth and vector seismic data) and as our management has correspondingly higher expectations of it. This course helps us understand how we can modify our practice to more fully realize the potential inherent in our data through algorithms which recognize the fact of seismic anisotropy.
The course offers a five-day immersion in the important ideas of seismic anisotropy, across the entire spectrum of applications, starting with fundamental ideas, and applying these to P-wave subsurface imaging and physical characterization, then to vector waves (S-waves and C-waves). It shows how isotropic seismics is just an introduction to a much richer range of phenomena. Although seismic anisotropy is always weak (as measured by elastic constants), it can have surprisingly large effects (more than 100%) in some contexts, and completely new effects in other contexts. These ideas assume particular importance for those geophysicists involved in the shale resource play.
Although 95+% of our data these days is P-wave data, the vector wave discussion is nevertheless important, as we will encounter these data-types more in the future, and, as you will see, the isotropic model is hopelessly naïve for such waves.
Numerous Excel exercises help students understand these ideas through their own hands. Some of these exercises offer computational functionality that is unavailable at most corporations.
- Physical principles (Day 1)
- P-waves: imaging (Day 2)
- P-waves: characterization (Day 3)
- S-waves: (Day 4)
- C-waves: (Day 5)
- Epilogue: (Day 5)
Applications of Linear & Non Linear Seismic Inversion
The goal of seismic processing is to extract useful and reliable information from seismic data relevant for locating and producing hydrocarbons. The goal of seismic research is to recognize, prioritize and provide effective responses to limitations in current seismic processing methods and capability. Seismic processing is a chain of interdependent steps, where the effectiveness of any given link in the chain depends on how effectively earlier links have executed and achieved their specific goals and purpose.
Among processing steps are the removal of free surface and internal multiples, and depth imaging and inverting primaries. In this course, we will trace the evolution, merging and extension of distinct methods originally designed to: (1) determine structure (depth migration), and (2) to identify changes in earth mechanical properties at a horizontal reflector( AVO), into migration-inversion, or first locating where something has changed before determining what specifically has changed at that location: hence, migration before inversion, in a multi-D subsurface.
We will describe what resides behind seismic processing failures, and subsequent dry hole drilling, and how methods developed for removing multiples have arisen and responded to that challenge, and how newer methods for locating and identifying petroleum targets are being researched and developed to continue the campaign of addressing fundamental imaging and exploration challenges. The prerequisites and assumptions behind processing methods (including these newer methods) will be described, as well as certain methods to satisfy these requirements. Important open issues without even a candidate response , will be described, requiring fundamental new thinking, research and concept development.
This course surveys and samples a history of increased seismic prediction effectiveness, with a simultaneous celebration of progress and a clear and frank recognition that today’s reasonable assumption will be tomorrow’s obstacle to further progress, with always more yet to be done.
- When are seismic processing methods effective and when do they fail?
- How to respond to seismic method failure; two approaches towards developing greater processing effectiveness;
- Green’s theorem and linear superposition- for wave field prediction (downward continuation and imaging) and wave field separation ( deghosting and wavelet estimation)
- Green’s functions and their role in seismic processing
- D’Alembert and Green’s theorem to demonstrate explicit relationship of FK Stolt and Green’s theorem Schneider migration
- Analog from NMO-stack to AVO and Migration to migration-inversion: linear inverse scattering theory; a new Green’s theorem method for RTM removes need for PML
- The linear migration methods( for example, Green’s theorem, FK , Beam, RTM) all locate structure requiring a velocity model above the target, but to identify properties changes at the target requires all information above the target- not only velocity
- Scattering theory: the forward series and the inverse scattering series (ISS)- the latter ISS allowing achieving all processing objectives directly and without subsurface information
- ISS subseries for removing free surface and internal multiples, directly and without subsurface information- algorithms are completely unchanged for any earth model type: acoustic, elastic, anisotropic, inelastic, heterogeneous- not one line of code changes.
- ISS subseries for depth imaging and inverting primaries; directly and without a velocity model- first field data examples
- Model matching is not inversion, and direct inverse methods to perform elastic parameter estimation require multi-component data, implications for P wave AVO and so called ‘ FWI ’.
- ISS subseries for Q compensation without Q
- Overview, anticipated new near-term delivery and capability and important open issues
Application & Interpretation of Converted Waves
This course provides a thorough overview of the methods of multi-component (3-C and 4-C) seismic exploration from basic petrophysical analysis and survey design through 3-D converted-wave migration. Numerous examples and case histories show the design, application, and use of multi-component surveys. Both 2-D and 3-D surveys and analysis will be discussed. Marine surveys (up to 4C-4D measurements) and analysis are highlighted. Supporting measurements as dipole sonic logs and 3-C VSP are also included. Field case interpretation exercises reinforce concepts introduced by the instructors.
- Rock properties: logs, synthetic seismograms, VSP, P and S velocity and density acoustic and dipole sonic logs, PP and PS AVO synthetics, 3-C VSP surveys and analysis.
- Multi-component acquisition: Sources, receivers, survey design, recording systems, logistics, cost.
- PS processing: Statics, velocity analysis, DMO, stacking, migration, inversion, anisotropy considerations.
- P- and S-wave interpretation: Section correlation, synthetics, VSP support.
- Field data exercises including: channel sand delineation, dolomite/anhydrite changes, 4C marine cases, conglomerate reservoir identification.
CSEM & MT Methods
This course gives an overview of CSEM and MT methods along with details on acquisition and processing of the data. Modeling and inversion are covered as well as the rock physics principles that facilitate the method. Applications through case studies of these tools are presented.
- Day 1:
- AM - Introduction
- PM - Sensitivity
- Day 2:
- AM - Acquisition and processing
- PM - Practical on Acquisition and Processing of CSEM and MT data (Computer Lab)
- Day 3:
- AM - Modelling and Inversion
- PM - Integration and case studies
- Day 4:
- AM - Case studies continued
- PM - Rock physics of resistivity
Electromagnetic & Potential Field Methods
This course discusses the foundations of potential and electromagnetic field methods. The recent developments in the gravity gradiometry and natural field and controlled source electromagnetic methods will be reviewed. We will discuss the fundamentals of regularized inversion of geophysical data and the practical aspects of solving inverse problems in geophysics. The course will provide an overview of the advanced methods of modeling, imaging, and inversion of potential and electromagnetic field data. Numerical examples of large-scale 3D inversion of the gravity, magnetic, and electromagnetic data will be presented to assist the students in understanding the state-of-the-art interpretation methods. The main objective of this short course is to present the key principles and ideas of modern forward modeling and inversion techniques and their applications to interpretation of the potential and electromagnetic field data.
- Review of foundations of field theory
- Principles of forward modeling of gravity, magnetic, and gravity gradiometry data
- Methods of forward modeling of electromagnetic fields
- Fundamentals of the regularized inversion of geophysical data
- Practical aspects of geophysical inversion
- Physical and mathematical principles of potential and electromagnetic field migration
- Migration imaging of gravity, magnetic, and gravity gradiometry data
- Regularized inversion of gravity, magnetic, and gravity gradiometry data
- Magnetotelluric (MT) and magnetovariational (MV) methods
- Marine MT and MV methods
- Three-dimensional inversion of the MT and MV data
- Marine controlled-source electromagnetic (MCSEM) methods
- Migration imaging of the MCSEM data
- Three-dimensional inversion of the MCSEM data
- Principles of joint inversion of different geophysical data
Fundamentals of Geophysical Data Processing
This “Fundamentals of Geophysical Data Processing” course is just that; it is an introductory course on fundamentals designed for individuals who work with seismic data. The course participants may be processing geophysicists, seismic interpreters or acquisition specialists. This course illustrates the ramifications of processing decisions on subsequent interpretations, showing data’s potential and the possible pitfalls for the unwary. The course is also of value for seismic acquisition specialists who desire to understand the constraints that seismic processing places on acquisition design.
This course presents material in a sequence that is the opposite of the sequence used in processing. In other words, the course presents the topics backwards, starting with migration and concluding with acquisition. Each processing step has its own input requirements; thus, understanding those input requirements provides the motivation for understanding the each preceding processing step.
Seismic processing is inherently mathematical. However, this course uses cartoons and real data examples to provide an intuitive understanding of the seismic processing procedures, resorting to an algebra-based argument on rare occasions. In total, the course contains more than one thousand illustrations, many representing the underlying mathematics.
The course participants receive the instructor’s eBook which contains the course content, including full narratives and illustrations.
- Simple imaging using zero-offset data, with the use of the NMO equation and Dix interval velocities
- Concept of zero-offset migration
- Artifacts introduced by migrating incomplete data, including 2D data
- Role of velocity in migration
- Kirchhoff and reverse-time, zero-offset migration algorithms
- Fourier transform (amplitude and phase), convolution and correlation
- Normal moveout correction and stack to convert data to zero offset
- Estimation of stacking velocities
- NMO and stack’s failures
- Kirchhoff before-stack migration
- Three imaging conditions and before-stack, wave-equation migration algorithms
- Multiple attenuation and role of wide-azimuth acquisition geometry in multiple attenuation
- Statics, land and marine
- Amplitude corrections
- 1-D and 2-D filtering, including f-k filtering
- Wavelets and deconvolution
- The Fresnel zone
- Improving spatial resolution
- Improving resolution of depth estimation
- Sample processing sequences
- Ramifications of processing decisions
Geophysical Data Processing
This course is designed to provide basic background and training for the processing of digital seismic data, particularly that used by the petroleum industry. The emphasis is placed on the principles and practicality of the major processing methods, statics, deconvolution, velocity analysis, stacking, and migration.
- Fourier analysis
- General properties of waves
- Data acquisition (2D, 3D, Marine)
- Understanding seismic events
- Survey predesign
- Statics, filtering, binning
- Creating the CMP stack
Microseismic Imaging & Interpretation
This course provides fundamental knowledge on hydraulic fracturing, fracture formation, microseismic data acquisition and processing, microseismic imaging and interpretation. The format of the class includes lectures and hands-on exercises on covered topics. This course is suitable for individuals who are interested in having a thorough understanding in microseismic theory and applications.
- 1.1 Shale reservoirs and hydraulic fracturing
- 1.2 Stress, strain, and fractures
- 2.1 Seismic waves and wave propagation
- 2.2 Microseismic data acquisition and processing
- 3.1 Microseismic event location
- 3.2 Microseismic size and focal mechanism
- 4.1 Velocity model building and seismic anisotropy
- 4.2 Moment tensor inversion
- 5.1 Low-frequency micro-earthquakes and induced seismicity
- 5.2 Interpretation of microseismicity
Practical Marine Electromagnetic Methods
Electromagnetic information can provide constraints on subsurface resistivity, independent of other information-sources such as down-hole resistivity logs. This course is designed to equip attendees with a strong understanding of the geophysical fundamentals of the Marine Magnetotelluric (MT) and Controlled-Source Electromagnetic (CSEM) methods, and also with practical experience at using CSEM data for improved exploration predictions.
You will learn how EM data are acquired, processed and imaged to generate sub-surface resistivity estimates. The accuracy and robustness of this reconstruction are discussed in detail, as a thorough understanding of the measurement-capabilities is key to its successful application. EM-focused rock physics fundamentals and practical interpretation frameworks are detailed, and the measurement is compared with other resistivity tools such as induction and triaxial-induction logs.
EM information has now been available to our industry for over 15 years. During this time, it has undergone considerable change and maturation. However, in stark contrast to other widely-used geophysical methods, EM has no standard place within the geophysical toolkits of most E&P companies today. During this course, we will review the various approaches available to integrate EM information into existing exploration processes, focusing on the approach that has proven most fruitful to date: improving exploration predictions through the integrated interpretation of EM and seismic information.
Exercises during the course will provide hands-on experience with EM modeling and inversion, and real-data interpretation using modern 3D EM datasets, accompanied with seismic and well data.
- Rock physics
- EM applications
- Information-integration approaches
The seismic inversion concepts and workflows to quantitatively integrate 3D seismic data into the reservoir model are discussed. Emphasis is placed on deterministic methods with geostatistical constraints to invert for reservoir and fluid properties and to incorporate these data into reservoir models.
- Introduction to geophysical characterization for reservoir modeling
- Rock Physics Basis: The Link Between Reservoir Properties and Seismic Response
- Direct Hydrocarbon Indicators
- Using Seismic Attributes to Determine Rock and Fluid Properties
- Stochastic Fluid Properties Inversion
- Integration of Geostatistics in Reservoir Model Building
- Time-Lapse Seismic Monitoring
- Fundamentals of Seismic Imversion
- Using Neural Networks to Generate Reservoir Property Cubes
- Spectral Decomposition: Methods and Applications
- Spectral Broadening: Developing Reservoir Models Below Conventional Seismic Resolution
Rock & Fluid Physics
This course reviews various physical properties of rocks and fluids and the seismic response to materials with those properties with direction applications to exploitation, exploration and geophysical modeling.
- Reservoir environment
- Elasticity of porous media
- Velocity of sandstone
- Velocity of poorly consolidated rock
- Velocity of carbonate
- Gassmann equation
- Optimal hydrocarbon indicator
- Hydrocarbon fluids properties
- Velocity dispersion and attenuation
- Seismic Rock Physics: Applications
Seismic Attributes for Carbonate Reservoirs
A seismic attribute is any measure of seismic data that helps us better visualize or quantify features of interpretation interest. Seismic attributes fall into two broad categories – those that help us quantify the morphological component of seismic data and those that help us quantify the reflectivity and kinematic components of seismic data. The morphological attributes help us extract information on reflector dip, azimuth, shape, and terminations, which can in turn be related to faults, channels, fractures, karst, and carbonate buildups. The reflectivity and kinematic attributes help us extract information on reflector amplitude, waveform, and variation with illumination angle, which can in turn be related to dolomite vs. limestone, reservoir thickness, fracture density and azimuth, and the present-day stress field. In the reconnaissance mode, 3D seismic attributes help us to rapidly identify structural features and depositional environments. In the reservoir characterization mode, 3D seismic attributes are calibrated against real and simulated well data to identify hydrocarbon accumulations and reservoir compartmentalization.
In this course, we will gain an intuitive understanding of the kinds of seismic features that can be identified by 3D seismic attributes, the sensitivity of seismic attributes to seismic acquisition and processing, and of how 'independent' seismic attributes can are coupled through geology. We will also discuss alternative workflows using seismic attributes for reservoir characterization as implemented by modern commercial software and practiced by interpretation service companies. Participants are invited to bring case studies from their workplace which demonstrate either the success or failure of seismic attributes to stimulate class discussion.
- Complex trace, horizon and formation attributes
- Color display and 3D visualization
- Spectral decomposition and thin bed tuning
- Mapping unconformities
- Volumetric dip and azimuth
- Angular unconformities
- Volumetric curvature
- The shape index
- Volumetric rose diagrams
- Lateral changes in amplitude
- Sobel filter similarity
- Amplitude gradients
- The gray-level co-occurence matrix (GLCM) and seismic textures
- Structure-oriented filtering and image enhancement
- Attribute illumination of carbonate structural deformation and geomorphology
- Tectonic deformation
- Carbonate deposition environments
- Reefs and bioherms
- Chalk reservoirs
- Chert reservoirs
- Karst and diagenetic alteration
- Hydrothermally-altered dolomite
- Clastic depositional environments – attribute expression of other features in the section
- Geomorphology of igneous intrusive and extrusive features
- Reservoir heterogeneity
- Impact of data quality on seismic attributes
- Velocities and statics
- Acquisition footprint
- Seismic migration
- Velocity anisotropy and amplitude vs. azimuth (AVAz)
- Microseismic experiments as a means to map the hydraulic fracturing
- Attributes applied to offset- and azimuth-limited volumes
- Multiattribute analysis tools
- Inversion for acoustic and elastic impedance
- Reservoir characterization workflows
- 3D texture analysis
Seismic migration is a key tool for constructing subsurface imagery based on industry seismic data. This short course aims to examine the basic methodology and underlining geophysical principles of seismic migration. Some common migration methods, such as Kirchhoff, phase-shift, and full-wave migration, will be studied and illustrated with literature examples. Relevant topics to be discussed include pre-processing of migration data and velocity model building. In particular, the dependency of migration on the velocity-depth model and migration velocity analysis will be analyzed. The course will focus on principles, practicality, and future directions of seismic migration.
- Introduction to Migration: Definition and outline of methods, time processes before imaging, stacking velocities, math background.
- Common Tangent Method: The exploding reflector concept, hand-made migration, advantages and limitations.
- Kirchhoff Migration: Kirchhoff integral, Rayleigh integral, Kirchhoff migration, travel time and ray tracing.
- Time versus depth and poststack versus prestack migrations: Time migration, depth conversion of time migration, post-stack migration, pre-stack migration.
- Migration Velocity Analysis: Initial velocity model, depth and velocity ambiguity, focusing analysis, tomographic velocity analysis, residual curvature analysis.
- Frequency Domain Migration: Time versus frequency domains, geometrical overview of f-k migration, phase-shift migration.
- Finite Difference Migration: Approximations of up-going wave equation, retarded coordinates, finite differencing wave equations.
- Prestack Depth Migration: Kirchhoff depth migration, reverse time migration, full-wave migration.
Seismic Wave & Ray Theory
Fundamental concepts and foundations of wave and ray theory necessary for seismic processing, imaging, AVO analysis and structural interpretation.
- Elasticity theory, the wave equation, body waves.
- Partitioning at an interface, reflection at non normal incidence (AVO), reflection geometry and wave path curvature.
- Surface waves, scattering theory, attenuation and velocity, diffraction.
- Head waves, events and noise, resolution, wavelet shape, near surface properties. 5. S-waves and C-waves.
- Wave and ray theory concepts in processing, migration and imaging.
Velocity Analysis for Depth Imaging
Outline of Topics:
- Review of migration theory with an emphasis on what approximations affect our ability to build a representative subsurface velocity model.
- Wave theory versus ray theory
- Kirchhoff & Beam migration
- One-way versus two-way wavefield extrapolation
- Review of data pre-conditioning with an emphasis on what procedures affect our ability to build a representative subsurface velocity model.
- Velocity-dependant pre-processing
- Multiple suppression without velocity assumptions
- One-way versus two-way raypaths and effects of conventional processing on two-way raypaths
- Limits on resolution, accuracy and precision
- Picking, autopicking, fitting, & geostatistics
- Historical review of methods
- Overview of the principles of tomography & brief introduction to waveform inversion
- Azimuthal considerations: acquisition, orthorhombic versus factored ‘azimuthal+TTI’
- Case studies
- Simple and complex water
- Near surface effects: ways of building the near surface model
- Land and topography
- Complex salt model building
- Multi-azimuth issues and case studies
- Waveform inversion issues and case studies