Seismic Geomechanics: How to Build and Calibrate Geomechanical Models using 3D and 4D Seismic Data
Dr Jörg Herwanger, WesternGeco - London Gatwick, UK
Jörg Herwanger is a Principal Geophysicist in WesternGeco’s Research and Engineering Group in Gatwick, UK, developing workflows to build and calibrate 3D Earth models by integrating seismic inversion methods, rock physics, reservoir flow and geomechanical models. He joined WesternGeco in 2003.
His current work combines experimental observations and the development of mathematical models and workflows in time-lapse seismic, rock physics and reservoir geomechanics. Previously Jörg’s interest was in the development and computer implementation of tomographic methods to determine anisotropic electrical properties from observed crosswell data. He combined these newly developed techniques with anisotropic velocity tomography to detect and evaluate fractures.
He is a member of EAGE and SEG and served as an EAGE Distinguished Lecturer from 2007-2009. He has a Diplom degree from the Technische Universität Clausthal, Germany and a PhD from Imperial College, London, U.K., both in Geophysics.
Three-dimensional geomechanical models are becoming more frequently used to assess the state of stress inside the Earth. Knowledge of the stress-state in a reservoir and the surrounding rock allows assessing the risk of reservoir compaction, wellbore failure, sanding, breach of seal integrity, fault re-activation and allows the design of mitigation for these issues. Three-dimensional seismic data and inversion models can be used in building geomechanical models and time-lapse (4D) seismic data provide a means of calibrating the dynamic behavior of reservoir geomechanical models. The purpose of this course is to provide an overview of currently available workflows to build and run calibrated reservoir geomechanical models maximizing the use of 3D and 4D seismic data. Rock-physics, relating the state of stress in the Earth and the propagation velocity of seismic waves, forms the link between seismic observations and the geomechanical model, and this link will be discussed both from experimental data and from a theoretical viewpoint. Attendees will learn how a combination of 3D geomechanical models, coupled to flow models, built and calibrated with 3D and 4D seismic data help in creating a deep understanding of the reservoir depletion processes and the state of stress in the reservoir and surrounding rock.
- Field observations of geomechanically induced time-lapse seismic signals. Where do they occur and why?
- Building a 3D geomechanical model. Demonstrating a seismic-to simulation workflow, including building a framework model to surface and property population from seismically derived properties.
- Running coupled modeling of a reservoir simulation model and a geomechanical model. Non-linear stress-strain relationship, reservoir compaction, failure models, stress and strain tensors.
- Rock-physics for elastic and inelastic deformation. Velocity-stress relationship for elastic and inelastic deformation. Velocity during loading and unloading. Stress-induced velocity anisotropy.
- Time-lapse seismic observations. Time-lapse time-shifts, AVO attributes, shear-wave splitting.
- Case-study of integrating flow model, geomechanical model and time-lapse observations.
The purpose of this course is to
- Provide an overview over currently available workflows to build, run and calibrate reservoir geomechanical models maximizing the use of 3D and 4D seismic data;
- Apply the understanding gained from running such workflows to field development and reservoir management;
- Understand the limitations of current workflows and techniques and give a glimpse of the road ahead.
Who Should Attend?
The integrated nature of the subject and approach makes this course appealing to practitioners and researchers from a wide range of subsurface disciplines, ranging from geophysics, geomechanics, geomodelling, geology, rock physics and reservoir engineering. Practising geoscientists and engineers will appreciate the inter-disciplinary approach to addressing reservoir management issues and should be able to use ideas and approaches taught in this course in their day-to-day work.
The course draws heavily on field observations and examples, while limiting the use of mathematical developments. This makes the course appealing to a wide cross-section of geoscientists and engineers that are interested in the inter-related nature of the subsurface disciplines. It should also be appealing to managers of cross-disciplinary subsurface teams, increasing the appreciation of the complexity of the subsurface workflows that his or her team needs to address.
This course is aimed at geoscientists and engineers with an interest in integration between the different subsurface disciplines. The course presents both currently available seismic-to-simulation techniques. The course has an emphasis on making the physics behind the presented techniques accessible and clear and will appeal to curious and inquisitive people. This course is also suited for Master’s and PhD students as the course (material) is designed in such a way that the principles of geomechanics become clear.
Geomechanics is still a relatively new discipline in the oilfield environment and is not taught as part of most university Geoscience-programs. Therefore a lot of graphic examples to aid intuitive understanding are included in the course material..
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