Speaker: Ahmad Marvi Mashhadi
Date: Thursday 30th of November 2023, 1:15pm.
Abstract:
At the present time, however, the geological storage of H2 remains very little studied despite of the specific behaviour of this gas. A key point in the development of such technology is to characterize and constrain the biological processes that could alter qualitatively and quantitatively the resource within the storage framework in porous reservoir rocks. As first electron donor for life and crucial energy source for subsurface microbial processes, indeed, H2 allows the autotrophic growth of microorganisms under oligotrophic conditions (i.e. limited supply of carbon) in deep environments. In the presence of an available terminal electron acceptor such as nitrate (NO3-), ferric iron (Fe3+), sulfate (SO42-) or carbon dioxide (CO2), H2 is susceptible to be consumed by microorganisms to gain energy. To date, unravelling the contribution of H2-consuming microbes in the biogeochemical cycle of hydrogen is of high importance in a number of subsurface industries including H2 gas storage in the energy transition context. Particularly, bacterial activity is susceptible to produce methane (CH4) or hydrogen sulfide (H2S) to the detriment of H2. The main objective of this work will be to evaluate the kinetics of H2 consumption by bacterial model strains and multi-bacterial consortia under geological storage conditions in terms of temperature, pressure, salt concentration and electron acceptor availability. Batch and flow-through experiment will be designed to reproduce these storage conditions.
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- Category: Seminar
Speaker: Amandine Fratani
Date: Thursday 23rd of November 2023, 1:15pm.
Abstract:
During geological exploration, interpretation of faults can be ambiguous and uncertain because of disparate and often sparse observations such as fault traces on 2D seismic images or outcrops. The problem of associating partial fault observations was considered by Godefroy et al (2019), who decided to define a graph where each possible association of two fault observations (the graph nodes) are represented by an edge. The likelihood of this association was computed by using expert geological rules. However, fault observations are not pairwise independent, which limits the consideration of higher-order effects. For instance, the multiple-point association can be used to infer the evolution of the throw along the fault. In addition, the definition of rules in a multiple-point problem is also difficult because of the very large number of cases to consider. Here, we propose a machine learning approach to compute the likelihood of three-point fault data association. First, a computation of fault features (i.e. the length of the fault trace) from sections extracted from known 3D geological models is realized to create a data set of fault observations. The supervised machine learning problem is formulated as a classification problem to determine the probability that 3 fault observations belong to the same fault objects based on the feature vector. To prevent overfitting, we propose to mimic a partly interpreted case: we split the 3D domain in two disjoint sectors A and B, and use only data from sector A as training and data from sector B to test the method. However, the results are not conclusive, so an analysis of the features are proposed to choose the correct ones. At the same time, methods to deal with imbalanced dataset are explored.
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- Category: Seminar
Speaker: Consuelo Garcia Zavala
Date: Thursday 16th of November 2023, 1:15pm.
Abstract:
Lithium plays an essential role in global decarbonisation as lithium-based batteries are widely used in renewable energy and electric vehicles. The so-called “Lithium Triangle” extends over part of Chile, Argentina, and Bolivia, and holds around half of the world’s estimated reserves of lithium in the “salars”. Lithium extraction in this arid region raises challenges for the socio-ecological systems, which include fragile ecosystems and indigenous communities. Addressing these challenges requires companies to operationalise sustainability goals assuring continuous improvement of social and environmental performance, for which mining companies usually use socio-environmental management instruments. The question of whether these instruments are adequate to address the main social and environmental issues considering the particularities of this extractive activity taking place in unique geographic settings remains to be assessed. This project aims to understand the main socio-environmental issues associated with lithium extraction in the Lithium Triangle; and, through case studies, to assess whether existing socio-environmental assessment instruments are adequate for this activity and the complexity of this region.
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- Category: Seminar
Speaker: Enrico Scarpa
Date: Thursday 9th of November 2023, 1:15pm.
Abstract:
Starting from the 1990s, channel modeling research has been exploring how to replicate channel systems and examining the influence of modeling parameters on hydrocarbon recovery. Today, amid our strong commitment to ecological transitions, some of these investigations are shifting toward applications in CO2 storage and geothermal energy production. However, little attention has been directed towards understanding how facies elements within deposits affect the flow and heat transfer in geothermal energy systems. Often, small-scale heterogeneities in rock types are not represented in reservoir modeling due to the complexity of the geological models and the lack of data. This oversight leads to neglecting the reservoir connectivity of channel deposits. To tackle this absence, I aim to analyze how layers of shale within turbidite channels impact the performance of geothermal reservoirs. By using an appropriate stratigraphic grid setup, the volumes of the channels and the shale layers are preserved, allowing for the stochastic simulation of physical properties. Consequently, I will explore two geological scenarios: one with varied channels and another incorporating varied channels with shale layers. Using simple dynamic measurements, I will quantify the flow outcomes and compare these models. Results show that shale layers affect energy production, but the time for thermal breakthrough remains steady in both scenarios. This preliminary investigation prompts the inquiry of whether enhanced model realism is necessary for geothermal energy extraction.
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- Category: Seminar
Speaker: Jeremie Giraud
Date: Wednesday 8th of November 2023, 1:15pm.
Abstract:
This seminar will be divided into two main parts: In the first part, I will present an updated version of abstract S1214 that I presented in August at the IAMG 2023 Annual Meeting (Trondheim): I will introduce a trans-dimensional inversion technique for 3D gravity inversion, extending a multi-level set approach using signed-distance functions to model rock unit interfaces. It accommodates an unknown number of rock units through a birth-and-death process, allowing the addition or removal of units. It also allows the recovery of rock unit geometry and densities. In this presentation, I will show an application example in an undercover imaging scenario using data from the Boulia region (Queensland, Australia). Results suggest the presence of rock units concealed from surface geology and show the potential for the method to recover hidden geological features. In the second part, I will present some the non-scientific things I learned through my now-completed Marie Skłodowska-Curie Fellowship. The work that I will present was funded by the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 101032994.
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- Category: Seminar
Speaker: Massimiliano Schiavo
Date: Thursday 19th of October 2023, 1:15pm.
Abstract:
Groundwater pathways are permeable corridors where major subsurface discharges are conveyed. The ability to identify preferential groundwater pathways is crucial for a proper understanding of complex hydrogeological systems. These can be identified within a probabilistic framework upon two main ways of thinking, i.e. upon considering their delineation from an energy-based or a geologically-based perspective, both pursued from a geostatistical interpretation of available data. While both two methodologies rely upon geological data, like borehole and stratigraphic information, the former aims to identify the local aquifer bottom surface, and the latter considers only mostly permeable aquifer locations as suitable for being carved by a groundwater pathway. Both ways allow an in-depth understanding of the energetic and entropic behavior of such delineated pathways, consistent with other numerical, piezometric, and hydrogeological sources of information.
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- Category: Seminar
Speaker: Julien Herrero
Date: Thursday 12th of October 2023, 1:15pm.
Abstract:
This study presents a novel approach to handle structural uncertainties in the interpretation of stratigraphic structures using a transdimensional sampler, the reversible jump Markov chain Monte Carlo (RJMCMC) algorithm. Moving beyond conventional reservoir simulation models which use a fixed number of layers, the layering size is treated as variable. Hence, the number and position of model layers are unknowns to be determined by the inverse problem. The proposed method extends the application of one-dimensional RJMCMC by introducing a dip parameter, enabling the simulation of sedimentary wedges and erosional features around a well, which is not typically accounted for in standard layer-cake models used for instance in well test interpretation. To keep the model dimension low, a two-dimensional, piecewise constant permeability field is determined for each layering configuration. This inverse method, tested on a synthetic well log, facilitates robust interpretations of geological reservoir geometries and could improve the prediction of permeability spatial distribution in sedimentary settings. Demonstrating successful recovery of target models, the study opens interesting perspectives both for near-well subsurface models and full field reservoir models, and identifies the need for future work on allowing interface intersections to simulate more complex stratigraphic structures.
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- Category: Seminar
Speaker: Anne-Julie Tinet
Date: Thursday 5th of October 2023, 1:15pm.
Abstract:
Comprendre et modéliser le transport des contaminants est nécessaire pour évaluer la durée de vie et l’impact des sources de pollution et optimiser les stratégies de remédiation. Le transfert des contaminants de la phase NAPL (Non-Aqueous Phase Liquids) vers l'aquifère est un problème multi-échelle avec différents mécanismes de transport dans les phases et aux interfaces. Dans un 1er temps, des simulations à l’échelle du pore sont réalisées avec COMSOL en considérant un NAPL multicomposant avec pour objectif l’étude du coefficient d’échange. En effet, les modèles à l'échelle macroscopique comprennent des équations de transport pour chaque phase qui sont couplées par un ou plusieurs coefficients d'échange de masse. Alors que ces coefficients, qui intègrent les impacts des différentes caractéristiques à l'échelle des pores (géométrie des pores, distribution des phases, vitesse d'écoulement), jouent un rôle clé dans le devenir de la source de pollution, ils sont généralement approximés, pour une saturation de phase donnée, par une valeur constante estimée à partir de corrélations empiriques. Dans un 2e temps, des simulations macroscopiques de la dissolution de NAPL au niveau de la source de pollution représentée par un milieu hétérogène sont réalisées en faisant varier les conditions opératoires. Les courbes d’évolution des contaminants dissous prédites par la modélisation directe seront alors comparées aux résultats issus d’un modèle macroscopique 1D obtenu par changement d’échelle.
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- Category: Seminar