80th EAGE Conference & Exhibition 2018

Opportunities presented by the energy transition

11 - 14 June
Copenhagen, Denmark
Call for papers

Seismic Imaging with Ray and Waves - Where do we stand? Part I: Velocity Estimation


Sunday 10 June 2018

Title: Seismic Imaging with Ray and Waves - Where do we stand? Part I: Velocity Estimation 
Room: A
Convenors: P. Hardy (Total)
I. Jones (ION)
G. Lambaré (CGG)

Workshop Description

In the last decade, full wave methods have captured much attention in the research community. Numerous bodies of work have addressed those methods driven by the great promise of deriving high resolution volumes of subsurface properties using the entire seismic wave-field. However, ray methods are still widely used today. In fact, ray methods still make up most of our 3D seismic imaging project workflows, with Kirchhoff/beam migrations and tomography as the two principal components. Two main reasons explain this: ray methods are fast and robust whereas full wave methods still have technical challenges to resolve. Nowadays the two approaches are commonly used in conjunction to provide the best of both worlds.

Ray-based method limitations are well known theoretically: since rays are predicated on the high frequency asymptotic approximation of seismic wave propagation, they tend to be unstable (thus not well suited) in the presence of sharp, localised velocity contrasts. Ray based tomography also requires the extraction of kinematic attributes of usable (primary) seismic events from prestack gathers. It is said that those aspects cause instability in general, and limit ray based methods to the determination of low resolution velocity models. However significant progress has been made in recent years to overcome these limitations. Ray propagation can be made more robust, leading to more regular illumination, and efficient volumetric auto-pickers can now produce dense and reliable kinematic information without requiring parametric fitting. Some implementations of ray based tomography can handle very complex models and resolve velocity up to 15Hz!

FWI methods have made significant progress over the same period. New schemes have emerged to address the cycle skipping problem; new approaches have been proposed to work with more data such as primary and/or multiples reflected events, and work with more parameters in so-called multiparametric inversions. Various new reformulations of the objective function have been proposed to stabilize and accelerate the inversion process.

Successive step changes in both ray and wave based method formulation, or in parts of their workflow have therefore pushed the limits of their resolving power, and ongoing developments continue to have a significant impact. This workshop aims to illustrate practical and theoretical innovations that improve on the quality and resolution of the velocity images estimated with ray and/or wave based methods.

Who should attend

Researchers interested in seismic imaging and seismic velocities. 

Workshop Programme

Part 1 - Overview  
08:30 Introduction
08:35 An accurate Eulerian travel-time computation: implication for slope tomography
J. Virieux*(Univ. Grenoble Alpes), S. Sambolian (Univ. Cote d'Azur, Geoazur, CNRS), P. Le Bouteiller (Univ. Grenoble Alpes, ISTerre), S. Operto (Univ. Cote d'Azur, Geoazur, CNRS), A. Ribodetti (Univ. Cote d'Azur, Geoazur, IRD), B. Tavakoli (Univ. Cote d'Azur, Geoazur, CNRS)
09:10 Ray versus Full Wave Velocity Model Building - Status and

G. Lambaré (CGG)
09:30 The Evolution of Tomography and FWI
I. Jones* (ION), J. Singh (ION), P. Cox (Ophir Energy), M. Warner (Ophir Energy), C. Hawke (Ophir Energy), D. Harger (Ophir Energy), S. Greenwood (ION)
09:50 Discussion
10:10 Coffee break 
Part 2 - Wave Based Developments
10:30 Shaping the Velocity Model beyond the Diving Wave Penetration
D. Vigh* (WesternGeco), K. Jiao (WesternGeco), D. Sun (WesternGeco), X. Cheng (WesternGeco)
10:50 Migration Velocity Analysis with a Second-order Gauss-Newton Scheme - A 2D real data example
R. Soubaras* (CGG), B. Gratacos (CGG)
11:10 Integrating Reflection-FWI in Depth Imaging Velocity Model Building Workflows
C. Rivera* (TOTAl France), E. Bergounioux (TOTAL France), D. Ortiz-Rubio (TOTAL France), F. Audebert (TOTAL France)
11:30 From Reflection Waveform Inversion to Robust Velocity Estimate
Q. Guo* (KAUST), T. Alkhalifah (KAUST)
11:50 Discussion
12:10 Lunch break 

Part 3 - Ray Based Developments
13:00 Introduction
13:05 Understanding Resolution and Sharpness in Ray Based Tomography
D. Nichols* (Schlumberger), Y. You (Schlumberger) 
13:25 Nonlinear Slope Tomography - A versatile data- and challenge-driven velocity model building technique
P. Guillaume* (CGG), T. Allemand (CGG), F. Gamar (CGG), G. Lambaré (CGG), J. Messud (CGG), J. P. Montel (Total EP)
13:45 Multi-scale Traveltime Inversion - A robust method for velocity estimation in difficult geological context
C. Barnes* (Univ. of Cergy-Pontoise), M. Charara (Skolkovo  Institute of Science and Technology)
14:05 Direct Inversion of Seismic Reflection Data
P. Hardy (TOTAL)
14:25 Diffraction Wavefront Tomography - Efficient automated velocity inversion for multi-fold and single-channel data
A. Bauer* (Univ. of Hamburg), B. Schwarz (Univ. of Oxford), D. Gajewski (Univ. of Hamburg)
14:45 Discussion
15:05 Coffee break

Part 4 - Hybrid Approaches
15:25 Examples of Asymptotic Analysis for Understanding and Building Seismic Wave-equation Imaging Tools
H. Chauris* (MINES ParisTech), T. Zhou (MINES ParisTech), E. Cocher (MINES ParisTech), Y. Li (MINES ParisTech)
15:45 Machine Learning and Wave Equation Inversion of Skeletonized Data
G. Schuster (KAUST)
16:05 Borrowing Insight from Travel-time Reflection Tomography to Solve the Depth Reflectivity-velocity Coupling Issue of RFWI
R. Baina* (Opera), R. Valensi (Opera)
16:25 Traveltime Based Reflection Full Waveform Inversion
C. Wang* (ION Geophysical), P. Farmer (ION), D. Yingst (ION), I. Jones (ION), G. Martin (ION), J. Leveille (ION)
16:45 Discussion
17:00 End of workshop

Please note that this programme is subject to change.