Post-Doctoral Research Visit F/M Post-Doctoral research position: Modeling seismic wave equation propagation for geological CO2 storage monitoring on hex-dominant meshes

2022-05613 - Post-Doctoral Research Visit F/M Post-Doctoral research position: Modeling seismic wave equation propagation for geological CO2 storage monitoring on hex-dominant meshes

Contract type : Fixed-term contract

Level of qualifications required : PhD or equivalent

Fonction : Post-Doctoral Research Visit

Level of experience : Recently graduated

Context

About the Makutu joint research team

Makutu is a multidisciplinary project-team that has been created by Inria and TotalEnergies in January 2022 to address challenging numerical problems for the monitoring of CO2 storage. It is joint with University of Pau and Pays de l’Adour (UPPA), Institut Polytechnque de Bordeaux and CNRS. The team is composed of researchers, professor scientists and research engineers who are experts in the numerical simulation of wave propagation phenomena in complex media. The main applications of the team are the imaging of the near surface of the Earth applied to georesources problems, electromagnetism, the study of the interior of the sun and musical acoustics. The team has a wide range of competences which allows it to contribute to the fields of mathematical modeling, applied and numerical analysis, scientific computing and HPC.

Context

Geological storage of CO2 is a priority issue for Inria, as well as for TotalEnergies, whose ambition is to reach carbon neutrality by 2050. CO2 injection operations require long-term monitoring, which is mainly carried out via seismic imaging. This process requires a powerful software chain for the simulation of seismic wave propagation, including efficient numerical schemes and high-performance computing resources.

Within this context, the joint Makutu team, composed of TotalEnergies and Inria researchers and hosted by UPPA, is developing advanced numerical schemes for the simulation of wave physics into GEOSX, an open-source, multi-physics, multi-scale simulation platform jointly developed by Lawrence Livermore National Laboratories, Stanford University and TotalEnergies.

Based on an exascale-ready programming infrastructure, including the RAJA portability layer, the GEOSX simulation platform has been chosen by TotalEnergies to perform CO2 storage studies in an integrated manner, including fluid flow, geomechanics and geophysics simulations within the same framework and on the same models. However, the successful integration of seismic monitoring in GEOSX requires the introduction of new flexible and powerful numerical schemes.

Assignment

Assignment

The development of the first wave propagators into GEOSX, based on the Spectral Element Method (SEM) [1], has been carried out in 2021 and 2022. The SEM method is a continuous-Galerkin (CG) approach that is particularly efficient for time-explicit simulations, but whose formulation is mostly constrained to hexahedral meshes. This makes it especially difficult to couple seismic monitoring via SEM with existing reservoir and geomechanics simulation workflows, which run on more general meshes. In order to overcome this difficulty, the introduction of discontinuous Galerkin schemes (DG) [2] into GEOSX and their coupling with the existing SEM method [3] is a very promising approach. In particular, the Makutu team wants to address the following challenges:

Implementing into GEOSX efficient, parallel, hybrid SEM / DG schemes, which include and couple DG formulations on tetrahedra, the already-existing SEM continuous Galerkin (SEM-CG) formulation on hexahedra, as well as an innovative DG formulation on SEM hexahedral elements (SEM-DG).

Proving the advantages on the implementation of the above-mentioned algorithms on hex-dominant meshes, containing mostly hexahedra, with tetrahedra and other joining elements (pyramids, …).

Performing a mathematical and algorithmic analysis of the implementation of these methods on CPU and GPU HPC resources, with particular focus on exascale machines that will become available soon.

Testing and validating these schemes on TotalEnergies’ HPC platform Pangea3.

Application to real-world test cases of industrial relevance, in proximity with researchers and practitioners of the Makutu team and TotalEnergies’ Sustainability R&D.

Publication of relevant research on these numerical schemes, their HPC implementation, and their real-world applications.

Main activities

Main activities

• Work in proximity with the current Maktutu joint multidisciplinary research team.
• Gain an in-depth knowledge of the existing wave propagation numerical schemes in GEOSX, their structure and implementation.
• Perform, in collaboration with the Makutu team, the mathematical and algorithmic groundwork for the implementation of DG, SEM-DG and coupled numerical schemes for time-explicit wave propagation in GEOSX.
• Develop these schemes in C++, directly in the GEOSX platform, exploiting its portability layer to write efficient parallel code running on GPU.
• Optimize, validate, and test these methods on real-world scenarios such as seismic modeling and inversion, coupled seismic/reservoir and seismic/reservoir/geomechanics simulations on hybrid and hex-dominant meshes.
• Work with the Makutu team and with TotalEnergies’ Sustainability R&D teams to showcase these methods on real-world cases of industrial relevance.
• Help promote this work through publications, oral presentations, and conferences.

 

• [1] Komatitsch and J.-P. Vilotte. “The spectral element method: an efficient tool to simulate the seismic response of 2D and 3D geological structures”. In: Bulletin of the seismological society of America 88.2 (1998), pp. 368–392.

• [2] J. Grote, A. Schneebeli, and D. Schötzau. “Discontinuous Galerkin finite element method for the wave equation”. In: SIAM Journal on Numerical Analysis 44.6 (2006), pp. 2408–2431
  
• [3] Citrain. “Hybrid finite element methods for seismic wave simulation: coupling of discontinuous Galerkin and spectral element discretizations”. PhD thesis. Normandie Université, 2019.

Benefits package

• Subsidized meals
• Partial reimbursement of public transport costs
• Possibility of teleworking and flexible organization of working hours
• Professional equipment available (videoconferencing, loan of computer equipment, etc.)
• Social, cultural and sports events and activities
• Access to vocational training
• Social security coverage

Remuneration

2746€ / month (before taxs)