Speaker(s): Francois Bonneau
Date: Thursday 20th of August, 2:00 pm.
Abstract:
Fracture networks (FN) are systems of complex mechanical discontinuities, which dramatically impact the physical behavior of rocks. Their statistical characterization is an important first step of stochastic modeling. It is, however, a big challenge because field data are sparse and incomplete and present several biases due to sampling (censoring, truncation, orientation).
The present paper concentrates on the statistical analysis of outcrops, which often may be considered as planar sections through three-dimensional FN. For the corresponding planar FN there exist well elaborated statistical methods, which yield first-order characteristics such as fracture density or fracture length distributions. Using ideas from stochastic geometry, in particular the theory of fiber processes and marked point processes, we develop second-order characteristics such as pair correlation function and mark correlation functions, which describe the variability of planar FN and their inner spatial correlations. Surprisingly, one of these characteristics is closely related to characteristics used in statistics of fractals applied to FN.
We demonstrate the application of our ideas by field outcrops already published in the literature.
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- Category: Seminar
Speaker(s): Corentin Gouache
Date: Thursday 09th July 2020 - 02:00 pm
Abstract:
Most of the seismic active regions are localised along plate boundaries, thus spatial distribution of earthquakes is also clustered along these boundaries. Moreover with high accumulation rates (>1cm/y) one can expect the area of the next large earthquakes. These findings aren't true for Stable Continental Region (SCR) like French mainland. In these territories, seismic events seem to be uniformly distributed in space. Furthermore, some observations express a dependency behaviour between SCR earthquakes, as in seismic sequences but over hundreds of years. These findings are taken in account into the Generator of Earthquakes for Barely seismic areas.
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- Category: Seminar
Speaker(s): Paul Baville & Capucine Legentil
Date: Wednesday 01st July 2020 - 11:00 am
Abstract:
We will briefly present how Bezier interpolator works and its utility to generate chronostratigraphic lines (2D) or surfaces (3D) from well markers (dip and strike data). Once these lines generated, it is possible to extrapolate them using a signed distance function within a 2D meshed model (3D is the next step).
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- Category: Seminar
Speaker(s): Guillaume Caumon
Date: Thursday 18th June 2020 – 11:00 am
Abstract:
In this talk, I briefly review some key machine learning principles and report on some recent work using convolutional networks for the structural interpretation of seismic images.
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- Category: Seminar
This seminar is the occasion to present my PhD work on a method to robustly introduce boundaries in a triangulated geomodel, that allows the integration of new data, simulation results or geometry perturbation to reflect the subsurface uncertainties. The 2D geological model is locally updated, meaning that only a given region is modified and that the rest of the model remains identical. The area that can be modified is either specified as an input parameter or defined automatically. The input data is a triangulated surface storing the geological structure and physical properties. I will focus on the insertion of a horizon implicitly defined by an iso-value of a scalar field. The output is an updated mesh, which contains the new horizon. Distinctly from current model modification, the modifications are made to the mesh and aim to keep it valid throughout the transformations. The representation of geological structures as well as the computational support (mesh) can impact physical simulations. Once the local remeshing has been made, the impact of these updates on the model's physical behavior is evaluated thanks to the comparison of wave propagation profiles. These profiles are simulated using a Discontinuous Galerkin method.
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- Category: Seminar
Speaker(s): Marcus Apel
Date: Thursday 04th June 2020 – 2 :00 pm
Abstract:
In the Spring of 2018, a group of leading oil and gas companies met to discuss how contemporary cloud technology could be used to transform the current complex data and application environment. The Open Subsurface Data Universe™ (OSDU) Forum, a Forum of The Open Group, was created with the objective of enabling new cloud-native data-driven applications with seamless access to the full range of subsurface and wells data as well as supporting existing applications and data frameworks. The core principle of the OSDU solution is to separate data from applications. This will be achieved by developing a common data platform with standard public APIs and to involve global cloud hosting vendors to build working implementations. The focus of this presentation will be on data models and data architecture for geomodelling.
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- Category: Seminar
Speaker(s): Antoine Mazuyer
Date: Thursday 13th May 2020 - 11:00 am
Abstract:
Geological sequestration of CO2 in large quantity is one of the most promising methods to curb global warming. To achieve this goal, large volumes of CO2 have to be permanently stored in geological reservoirs. Modeling and simulating CO2 sequestration is a multi-disciplinary effort involving a large spectrum of physical and chemical phenomena. We focus this work on the generation of 3D structural models and meshes to support coupled numerical simulations with flow and poromechanical equations. Building such models and meshes is challenging as the poromechanical changes to stresses and strains are not limited to reservoir layers where CO2 is stored, but also in the surrounding formations (overburden, underburden, sides). Modeling surrounding rock formations is necessary to capture fault reactivation, uplifting and caprock failure issues during the injection. In this work, we propose guidelines to build such models using implicit and explicit modeling strategies and meshes. This work is supported by real field data from a depleted gas field in the Gulf of Mexico state water. This field is considered as a faithful analog to CO2 sequestration reservoirs in the regional Miocene sands.
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- Category: Seminar
Speaker(s): Bruno Levy
Date: Wednesday 06th May 2020 - 2:00 pm
Abstract:
There is a lot of scientific activity around Optimal Transport (OT for short), that has became a "buzzword". OT is at the connection between math, physics and computer science. It has also some interesting applications in AI, which attracted even more attention to it. In this presentation, I will take a completely different path: I will introduce OT with a physicist's hat on my head: My goal is to give an intuitive idea of OT, and its connections with physics. In particular, OT can be used as a component of a new class of numerical simulation methods, with interesting properties. In particular, it is possible to design a king of "moving mesh method" while exactly controlling the volume of the mesh elements. This can be used to simulate fluids, or to solve some inverse problems in astrophysics.
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- Category: Seminar