Oil and Gas
Oil and Gas | Geophysics and Seismic Interpretation
Seismic Inversion and Applications to Stochastic Reservoir Modelling
Format and Duration:
4 days
8 sessions
The course covers well-tie and zero-phasing issues, wavelet estimation, Acoustic Impedance Inversion, pitfalls in inversion, upscaling of well logs (Backus upscaling), attribute analysis and stochastic inversion methods. Extensive use is made of examples and exercises.
Business Impact: This practical course explains the principles of inversion from seismic data to rock properties, emphasising the analogies with geostatistics. It demonstrates that seismic inversion must be considered as a stochastic process/exercise and, by extensive use of examples, provides a non-mathematical basis for understanding the concepts.
Feedback
Very informative. The instructor was fantastic.
Schedule
Duration and Training Method
This is a classroom or virtual classroom course, comprising short lectures, discussion, case studies, and practical exercises.
Course Overview
Learning Outcomes
Participants will learn to:
- Assess the quality of the key well-tie process, fundamental to seismic interpretation projects.
- Perform fluid replacement analysis and Backus upscale modelling on the wavelet in the well-tie process.
- Design a simple seismic modelling strategy to examine tuning and fluid effects using wedge models.
- Evaluate how a wavelet may be constructed that most closely resembles the base seismic, and the pitfalls such an estimation may encounter.
- Appraise the various methods of seismic inversion and their value to interpretation, including model-based methods, structural deconvolution and Relative Acoustic Impedance.
- Compare inversion methodologies and results with the wider family of seismic attributes.
- Assess the principles of geostatistics in its role as spatial correlation estimator and relation to simpler averaging and correlation strategies.
- Compare kriging and best estimation seismic inversion approaches and the role of stochastic simulation in removing bias in best estimate inversion calculations.
- Evaluate how inversion results can be integrated with well data, using various strategies, such as kriging with external drift and co-kriging.
- Rate the latest inversion technologies and role of stochastic methods in their development.
- Assess the potential pitfalls of inversion.
Course Content
1. To Tie a Well
- Phase
- Wavelets
- Checkshot Calibration
- Fluid Replacement Modelling
- Backus Upscaling
- Synthetic Modelling
2. Wavelet Estimation
- Determining wavelets directly from seismic
- Strategies for wavelet estimation - Kurtosis, amplitude envelope, cross-correlation
- Phase in VSP datasets will be considered, downgoing wavefield deconvolution (deterministic deconvolution) in zero phasing VSP upgoing wavefields
- Wavelet estimation using well logs - statistical extraction, full extraction, Roy White method
- Practical exercise
- Inversion as zero phase deconvolution, integration (inversion itself) and scaling to absolute values (the model component)
3. Acoustic Impedance Inversion
- Inversion methods - model-based methods, structural deconvolution as used in VSP and Relative Acoustic Impedance Inversion (RAI)
- L1 and L2 norms - minimisation strategies.
- Inversion as a well/seismic integration method - similarities to kriging
4. Geostatistics Primer
- Importance of the average or mean in estimation
- Expectation or probability weighted outcome.
- Discussion of correlation and correlation coefficient and confidence intervals.
- Spurious correlation Java Applet
- Estimation using spatial correlation - kriging
- Comparison between kriging and best estimation in acoustic impedance inversion
- Bias under best estimate computations - its solution using stochastic simulation
- Kriging with external drift, co-kriging, collocated co-kriging with Markov-Bayes
5. Pitfalls in Inversion
- Over-zealous stretch and squeeze in wavelet estimation
- Artefacts in model-based inversion
- Non-uniqueness
- Trace scaling and normalisation
- Skew in cumulative distribution function.
- Estimator shrinkage (the similarity with kriging will be illustrated).
6. Inversion Practicals
- Practical investigation using a full sized field data set comprising 2D seismic data and well logs
- Time picking
- Model building
- Wavelet estimation
- Interpretation of results.
- Examples of 3D seismic inversion
7. Stochastic Inversion Methods
- The latest inversion techniques using stochastic methods
- The necessity of developing stochastic approaches
- Link with geostatistics
- The problems associated with stochastic methods - speed, enormous quantities of output data produced
- The future of these methods
Who Should Attend and Prerequisites
Geophysicists and geologists. An understanding of basic mathematics and physics is required.
Instructors
Ashley Francis
Background
Ashley is Managing Director for Wessex Geoscience Ltd, having co-founded this company with Julie Francis in 2022. He is a geophysicist and geostatistician whose career has encompassed over 30 years worldwide oil industry experience of exploration, development, and production geophysics. Ashley has also consulted to the nuclear and engineering sectors on subsurface definition and uncertainty.
Ashley has worked in or on behalf of service companies, consultancies and oil companies in North and South America, Europe, Africa, the Middle East, the Far East, and Australia. He spent 5 years with LASMO plc in Technical Services assisting and advising asset teams worldwide in geophysics (particularly inversion), geostatistics, risk and uncertainty. After leaving LASMO in 2001, Ashley co-founded Earthworks, a consultancy specialising in subsurface geoscience. In addition to services and training, Ashley also developed ultra-fast stochastic seismic inversion software at Earthworks.
Ashley lectured in Borehole Geophysics to Honours Graduates at the University of the Witwatersrand, South Africa in 1989-90 and was a Visiting Research Fellow at the Post Graduate Institute in Sedimentology, University of Reading, UK in 1995-97. Ashley has presented regularly at EAGE conferences and workshops and was author of the ‘Understanding Stochastic Inversion’ tutorial series in First Break. Ashley is a committee member and regular attendee at the SEG Development and Production Forum and chaired the 2000 and 2003 D&P Forum conferences. He was an SPE Distinguished Lecturer for 2006–2007, presenting worldwide to reservoir engineers on the benefits and pitfalls of seismic inversion data in reservoir modelling. In 2001, the EAGE presented him with the Anstey Award for his ‘very substantial, original and diverse contribution to seismic inversion and geostatistics, and to the quantifying of uncertainty and risk’.
Affiliations and Accreditation
SEG, EAGE, IAMG, BSSS, IPSS, and PESGB - Member
Fellow of the Royal Astronomical Society
Courses Taught
N031: Prospect Evaluation & Volumetric Methods (Dorset, England)
N045: Seismic Inversion and Applications to Stochastic Reservoir Modelling
N216: Geostatistics and Advanced Property Modelling in Petrel
N224: Methods for Quantifying and Communicating Uncertainty in Depth Conversion and Volumetrics
Accreditation and Certification
CEU: 2.8 Continuing Education Units
PDH: 28 Professional Development Hours
Certificate: Certificate Issued Upon Completion
RPS is accredited by the International Association for Continuing Education and Training (IACET) and is authorized to issue the IACET CEU. We comply with the ANSI/IACET Standard, which is recognised internationally as a standard of excellence in instructional practices.
We issue a Certificate of Attendance which verifies the number of training hours attended. Our courses are generally accepted by most professional licensing boards/associations towards continuing education credits. Please check with your licensing board to determine if the courses and certificate of attendance meet their specific criteria.