Full-Waveform Inversion for High-Resolution Reservoir Characterization
By: Prof. Dr Dries Gisolf
Instructor
Prof. Dr. Dries Gisolf
(Delft Inversion, Delft, Netherlands)
Duration
14 - 15 February 2023:
9:00AM-1:00PM CET
4 hours/day
Disciplines
Geophysics – Surface Imaging
Course Format
The EAGE Interactive Online Short Courses bring carefully selected courses of experienced instructors from industry and academia online to give participants the possibility to follow the latest education in geoscience and engineering remotely. The courses are designed to be easily digested over the course of two or three days. Participants will have the possibility to interact live with the instructor and ask questions.
Education Packages
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Course Description
The purpose of this course is to teach participants the fundamentals of extracting quantitative property information from seismic data. In the end this leads to an inversion process, which is called linear if the data are supposed to consist of primary reflections only and the reflection coefficients are linearised in the property contrasts across interfaces. The inversion becomes non-linear if all multiple scattering and multiple mode conversion over a target interval around the reservoir are taken into account. Non-linear inversion leads to a higher resolution than obtained from conventional linear inversion techniques.All steps required in these processes are based on the wave equation and it is important, therefore, to have a good understanding of the acoustic and elastic wave equations. In linear (AVO) inversion, first the reflection coefficients are derived from the data and subsequently the rock properties are derived from the reflection coefficients. In non-linear inversion, the properties are directly derived from the data. The non-linear inversion presented in this course is an iterative process in which in every iteration a higher order of scattering in the data is taken into account. The method is based on an integral representation of the wave equation. An important aspect of reservoir oriented wave-equation based inversion is that the surface recorded data are localized (focused) to the target area. This can be achieved by redatuming or by local demigration of migrated data.Both the linear AVO data model in terms of reflection coefficient sand the non-linear data model in terms of property contrasts against backgrounds are presented. Inversion, linear, or non-linear, requires regularization. Several regularization options are presented.Finally, non-linear inversion at the reservoir scale is demonstrated by highly realistic synthetic reservoir models and real data case studies. The real data case studies include the extraction of low-frequency models (backgrounds) from well data and the extraction of angle dependent wavelets from the seismic-to-well match.
Course Objectives
Upon completion of the course, participants will be able to:
- Understand what quantitative property information is contained in seismic data and how to extract it.
- Make better judgements as to what inversion method to apply to what problem.
- Adopt a more quantitative approach to seismic-to-well matching and low frequency background model extraction
- Further the role of reservoir geophysics in multidisciplinary projects.
Course Outline
- Introduction
- The acoustic wave equation in in homogeneous media
- Integral representations of the acoustic wave equation. The Scattering Integral (Lippmann-Schwinger equation). P-wave and S-wave propagation. The role of migration in AVO inversion
- The non-linear data model for inversion; data equation and object equation; iterative, multiplicatively regularised inversion
- Applications based on an elastic full wavefield non-linear data model; realistic synthetic reservoir study, real data case studies including low-frequency model extraction and seismic-to-well matching. Synthetic time-lapse example.
Participants' Profile
This course is designed for geophysicists active in reservoirs and/or quantitative interpretation and processing geophysicists who would like to become involved in quantitative interpretation.
Prerequisites
Participants should have a basic training in geophysics and mathematics, particularly complex numbers and integrals.
About the Instructor
Prof. Dr. Dries Gisolf
Prof. Dr. Dries Gisolf graduated from the Delft University of Technology in 1971 and obtained his PhD at the University of Utrecht in 1975. In 1976 he joined Shell International Research Co. in Rijswijk, The Netherlands, as a seismic data processing geophysicist. Between 1980-2000 he held various positions for Shell in Oman, The Netherlands, Australia, Malaysia and Nigeria. Throughout his career with Shell he was involved in acquisition, processing and interpretation of seismic data, with an emphasis on quantitative prediction of reservoir properties. In September 2000 he was nominated as Professor of Acoustical Imaging and Sound Control at the Faculty of Applied Sciences at the Delft University of Technology. After retiring from TU Delft in 2010, he co-founded Delft Inversion in 2012, a service company providing high-resolution reservoir oriented inversion services to the oil and gas industry.