Speaker(s): Mustapha Zakari

Date: Friday 21^st of December 2018

Location: room G201, ENSG, Nancy

Abstract:

Fluid flow modelling is usually based on "averaging strategies" which allow to reduce the number of unknowns in order to obtain accurate and efficient models. Classic fluid models like Navier-Stokes ones consider fluid particles which are usually large group of molecules and model their behavior using macroscopic quantities like densities, averaged velocities and so on. At a larger scale, porous media flow models use macroscopic cells containing "fluid and solid" information like porosity and permeability. Finally at the reservoir modelling scale, blocks of these macroscopic cells are used and upscaling procedures applied to produce large scale efficient models. This presentation will briefly introduce each of these "Upscaling" strategies. In order to check the validity of unstructured mesh Upscaling strategies, a single phase Control Volume Finite Element Method reservoir model will be presented. This model based on unstructured mesh calculations is then compared to a similar TPFA (Two Point Fluid Approximation) model to check its higher accuracy.

Speaker(s): Corentin Gouache

Date: Thursday 13^th of December 2018

Location: room G201, ENSG, Nancy

Abstract:

During this seminar I will deal with seismic catalogues exhaustiveness. The goal is to find from which minimal threshold magnitude (cut magnitude) all the happened earthquakes have been recorded. This study is regionalized for the purpose of finding suspected different seismic behaviors according to geodynamical context. To do that, I will present you the catalogue that I use. Then I will show you different methods used to find the cut magnitudes of each catalogue (one per region). Finally I will discuss results coherency by applying scale laws on these supposed exhaustive catalogues.

Speaker(s): Nicolas Mastio

Date: Thursday 29^th of November 2018

Location: room G201, ENSG, Nancy

Abstract:

Time-lapse seismic has become a useful tool for reservoir monitoring and well stability assessment. Geophysicists have developed numerous methods to retrieve time-lapse attributes for the reservoir and for the overburden. However, these methods do not consider the physical differences between these two area during the inversion process. From a theoretical perspective, the elastic properties depend on the stress state. Consequently, this induces an anisotropy in the time-lapse velocity change which can have various origins: reservoir compaction, rocks damaging, etc.

Edgar and Mastio (2017) expose a reflection travel time tomography adapted to retrieve the time-lapse velocity change. An extension of this method which considers velocity change general anisotropy is presented and applied to a real case.

Speaker(s): Pauline Collon

Date: Friday 23rd of November 2018

Location: room G201, ENSG, Nancy

Abstract:

During this seminary, I present an overview of all the works related to the karstic systems thematic that have been carried out over the last ten years at RING. I emphasize especially two complementary aspects I worked on: the stochastic simulation of karstic systems and the statistical analysis of existing karstic networks.

Speaker(s): Corentin Gouache

Date: Friday 12th of October 2018

Location: room G201, ENSG, Nancy

Abstract:

Ce séminaire sera l'occasion de faire découvrir aux 3A l'IAMG (International Association for Mathematical Geosciences) et son Student Chapter. L'IAMG est l'association scientifique la plus proche des thématiques de recherche de l'équipe, et possède un Student Chapter à Nancy, qui est géré par les doctorants de l'équipe.

Speaker(s): Paul Cupillard

Date: Friday 14th of September 2018

Location: room G201, ENSG, Nancy

Abstract:

We present a general concept for evolutionary, collaborative, multiscale inversion of geophysical data, specifically applied to the construction of a first-generation Collaborative Seismic Earth Model. This is intended to address the limited resources of individual researchers and the often limited use of previously accumulated knowledge. Model evolution rests on a Bayesian updating scheme, simplified into a deterministic method that honors today’s computational restrictions. The scheme is able to harness distributed human and computing power. It furthermore handles conflicting updates, as well as variable parameterizations of different model refinements or different inversion techniques. The first-generation Collaborative Seismic Earth Model comprises 12 refinements from full seismic waveform inversion, ranging from regional crustal- to continental-scale models. A global full-waveform inversion ensures that regional refinements translate into whole-Earth structure.