Numerical simulation of forerunning fracture in saturated porous solids with hybrid FEM/Peridynamic model

In this paper, a novel hybrid FEM and Peridynamic modeling approach proposed in Ni et al. (2020) is used to predict the dynamic solution of hydro-mechanical coupled problems. A modified staggered solution algorithm is adopted to solve the coupled system. A one-dimensional dynamic consolidation problem is solved first to validate the hybrid modeling approach, and both -convergence and -convergence studies are carried out to determine appropriate discretization parameters for the hybrid model. Thereafter, dynamic fracturing in a rectangular dry/fully saturated structure with a central initial crack is simulated both under mechanical loading and fluid-driven conditions. In the mechanical loading fracture case, fixed surface pressure is applied on the upper and lower surfaces of the initial crack near the central position to force its opening. In the fluid-driven fracture case, the fluid injection is operated at the centre of the initial crack with a fixed rate. Under the action of the applied external force and fluid injection, forerunning fracture behavior is observed both in the dry and saturated conditions.Comment: arXiv admin note: text overlap with arXiv:2307.1092

Inverse modeling of nonisothermal multiphase poromechanics using physics-informed neural networks

We propose a solution strategy for parameter identification in multiphase thermo-hydro-mechanical (THM) processes in porous media using physics-informed neural networks (PINNs). We employ a dimensionless form of the THM governing equations that is particularly well suited for the inverse problem, and we leverage the sequential multiphysics PINN solver we developed in previous work. We validate the proposed inverse-modeling approach on multiple benchmark problems, including Terzaghi's isothermal consolidation problem, Barry-Mercer's isothermal injection-production problem, and nonisothermal consolidation of an unsaturated soil layer. We report the excellent performance of the proposed sequential PINN-THM inverse solver, thus paving the way for the application of PINNs to inverse modeling of complex nonlinear multiphysics problems

Estudo numérico e experimental de geomecânica não-linear acoplada a escoamento de fluido em reservatórios

Orientador: Philippe Remy Bernard DevlooTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica, Instituto de GeociênciasResumo: A produção de reservatórios pode levar a uma diminuição na pressão do fluido durante a vida útil da produção. O decaimento da pressão dos poros pode alterar a distribuição das tensões in situ e causar um aumento nas tensões efetivas. A deformação associada às tensões efetivas pode levar à compactação do reservatório, perda de permeabilidade e subsidência da terra. Para lidar com tais problemas, é necessário a geomecânica acoplada com escoamento do reservatório. Existem quatro objetivos principais nesta tese: 1) Propor um esquema sequencial aprimorado para desenvolver um simulador acoplado de escoamento e geomecânica não-linear, 2) Implementar modelos elastoplásticos para geomecânica e aplicar modelos de permeabilidade para reservatório, 3) Analisar a permeabilidade dependente de deformação, colapso de poros e compactação aprimorada por cisalhamento em reservatórios, 4) Calibrar os parâmetros de materiais em modelos elastoplásticos. Para apresentar o simulador de geomecânica e escoamento acoplados, propõe-se pela primeira vez um algoritmo sequencial aprimorado e implícito (ESFI), com um esquema de divisão de tensão fixa. O algoritmo sequencial totalmente implícito (SFI) é um método popular para aproximar um sistema acoplado, mas ocasionalmente sofre de convergência lenta ou mesmo falha de convergência. Para melhorar o desempenho do algoritmo SFI, uma nova técnica de aceleração não linear é proposta empregando transformações de Shanks para aprimorar a convergência do loop externo, com um método Quasi-Newton considerando o método Thomas modificado para o loop interno. No algoritmo ESFI, a formulação de fluidos é definida pela lei de Darcy, incluindo modelos de permeabilidade não linear. A deformação da rocha inclui uma parte linear sendo analisada com base na teoria de Biot e uma parte não linear sendo estabelecida através de modelos elastoplásticos. As derivadas temporais são aproximadas por um método implícito de Euler e discretizações espaciais são adotadas usando elementos finitos em duas formulações diferentes. Para analisar a permeabilidade dependente de deformação em reservatórios, usam-se modelos de permeabilidade não-lineares baseados em porosidade, como Costa, Petunin, Nelson e Davies. Para expressar a deformação, são implementados modelos elastoplásticos, por exemplo, Mohr-Coulomb, DiMaggio-Sandler e Cam-Clay modificado. Para indicar o início do colapso dos poros e da compactação aprimorada por cisalhamento e seu impacto na porosidade, permeabilidade e fluxo, são aplicados os modelos de limite de plasticidade e permeabilidade acopladas. Para calibrar os parâmetros de materiais em modelos elastoplásticos, propõe-se uma estratégia que minimiza a diferença entre resultados experimentais e numéricos, aplicando os métodos de otimização iterativa. Para calibrar os parâmetros do modelo de maneira adequada e rápida, foram desenvolvidas equações analíticas para fornecer dados iniciais para cada parâmetroAbstract: Production from hydrocarbon reservoirs can lead to a decrease in the fluid pressure over the lifetime of production. The pore pressure depletion can change the in-situ stresses distribution and cause an increase in effective stresses. Deformation associated with the effective stresses may lead to reservoir compaction, permeability loss and land subsidence. In order to tackle these problems, the coupled geomechanics and reservoir fluid flow is required. There are four main goals in this thesis: 1) To propose an enhanced sequential scheme to develop a coupled nonlinear geomechanics and reservoir simulator, 2) To implement elastoplastic models for geomechanics and apply permeability models for reservoir, 3) To analyze strain-dependent permeability, pore collapse and shear-enhanced compaction in reservoirs, 4) To calibrate the physics-based elastoplastic models. To present coupled geomechanics and reservoir simulator, we propose for the first time an enhanced sequential fully implicit (ESFI) algorithm with a fixed stress split scheme. The sequential fully implicit algorithm (SFI) is a popular method to approximate a coupled system, but it occasionally suffers from slow convergence or even convergence failure. In order to improve the performance of SFI algorithm, a new nonlinear acceleration technique is proposed by employing Shanks transformations to enhance the outer loop convergence, with a Quasi-Newton method considering the modified Thomas method for the internal loop. In this ESFI algorithm, the fluid formulation is defined by Darcy¿s law including nonlinear permeability models. The rock deformation includes a linear part being analyzed based on Biot¿s theory and a nonlinear part being established using elastoplastic models. Temporal derivatives are approximated by an implicit Euler method and spatial discretizations are adopted using finite element in two different formulations: the first one uses a continuous Galerkin for poro-elastoplasticity and Darcy¿s flow; the second one uses a continuous Galerkin for poro-elastoplasticity and a mixed finite element for Darcy¿s flow. To analyze the strain-dependent permeability in reservoirs, we use nonlinear permeability models based on porosity such as, Costa, Petunin, Nelson, and Davies. To express the deformation, we implement elastoplastic models, e.g., Mohr-Coulomb, DiMaggio-Sandler, and modified Cam-Clay. To indicate the onset of pore collapse and shear-enhanced compaction and their impact on porosity, permeability, and flux, we apply the coupled cap plasticity and permeability models. To calibrate the physics-based elastoplastic models, we propose a strategy that minimizes the difference between experimental and numerical results by applying the iterative optimization methods. To calibrate the model parameters properly and fast, we develop analytical equations to provide initial data for each parameterDoutoradoExplotaçãoDoutor em Ciências e Engenharia de Petróleo2014/00090-2FUNCAM

GeomInt–Mechanical Integrity of Host Rocks

This open access book summarizes the results of the collaborative project “GeomInt: Geomechanical integrity of host and barrier rocks - experiment, modeling and analysis of discontinuities” within the Program: Geo Research for Sustainability (GEO: N) of the Federal Ministry of Education and Research (BMBF). The use of geosystems as a source of resources, a storage space, for installing underground municipal or traffic infrastructure has become much more intensive and diverse in recent years. Increasing utilization of the geological environment requires careful analyses of the rock–fluid systems as well as assessments of the feasibility, efficiency and environmental impacts of the technologies under consideration. The establishment of safe, economic and ecological operation of underground geosystems requires a comprehensive understanding of the physical, (geo)chemical and microbiological processes on all relevant time and length scales. This understanding can only be deepened on the basis of intensive laboratory and in-situ experiments in conjunction with reliable studies on the modeling and simulation (numerical experiments) of the corresponding multi-physical/chemical processes. The present work provides a unique handbook for experimentalists, modelers, analysts and even decision makers concerning the characterization of various types of host rocks (salt, clay, crystalline formations) for various geotechnical applications

Computational Modelling of Concrete and Concrete Structures

Computational Modelling of Concrete and Concrete Structures contains the contributions to the EURO-C 2022 conference (Vienna, Austria, 23-26 May 2022). The papers review and discuss research advancements and assess the applicability and robustness of methods and models for the analysis and design of concrete, fibre-reinforced and prestressed concrete structures, as well as masonry structures. Recent developments include methods of machine learning, novel discretisation methods, probabilistic models, and consideration of a growing number of micro-structural aspects in multi-scale and multi-physics settings. In addition, trends towards the material scale with new fibres and 3D printable concretes, and life-cycle oriented models for ageing and durability of existing and new concrete infrastructure are clearly visible. Overall computational robustness of numerical predictions and mathematical rigour have further increased, accompanied by careful model validation based on respective experimental programmes. The book will serve as an important reference for both academics and professionals, stimulating new research directions in the field of computational modelling of concrete and its application to the analysis of concrete structures. EURO-C 2022 is the eighth edition of the EURO-C conference series after Innsbruck 1994, Bad Gastein 1998, St. Johann im Pongau 2003, Mayrhofen 2006, Schladming 2010, St. Anton am Arlberg 2014, and Bad Hofgastein 2018. The overarching focus of the conferences is on computational methods and numerical models for the analysis of concrete and concrete structures

Computational Modelling of Concrete and Concrete Structures

Computational Modelling of Concrete and Concrete Structures contains the contributions to the EURO-C 2022 conference (Vienna, Austria, 23-26 May 2022). The papers review and discuss research advancements and assess the applicability and robustness of methods and models for the analysis and design of concrete, fibre-reinforced and prestressed concrete structures, as well as masonry structures. Recent developments include methods of machine learning, novel discretisation methods, probabilistic models, and consideration of a growing number of micro-structural aspects in multi-scale and multi-physics settings. In addition, trends towards the material scale with new fibres and 3D printable concretes, and life-cycle oriented models for ageing and durability of existing and new concrete infrastructure are clearly visible. Overall computational robustness of numerical predictions and mathematical rigour have further increased, accompanied by careful model validation based on respective experimental programmes. The book will serve as an important reference for both academics and professionals, stimulating new research directions in the field of computational modelling of concrete and its application to the analysis of concrete structures. EURO-C 2022 is the eighth edition of the EURO-C conference series after Innsbruck 1994, Bad Gastein 1998, St. Johann im Pongau 2003, Mayrhofen 2006, Schladming 2010, St. Anton am Arlberg 2014, and Bad Hofgastein 2018. The overarching focus of the conferences is on computational methods and numerical models for the analysis of concrete and concrete structures