Propagation des ondes sismiques dans les milieux multiphasiques hétérogènes : modélisation numérique, sensibilité et inversion des paramètres poroélastiques

Seismic wave propagation in multiphasic porous media have various environmental (natural risks, geotechnics, groundwater pollutions...) and ressources (aquifers, oil and gas, CO2 storage...) issues. When seismic waves are crossing a given material, they are distorted and thus contain information on fluid and solid phases. This work focuses on the characteristics of seismic waves propagating in multiphasic media, from the physical complex description to the parameter characterisation by inversion, including 2D numerical modelling of the wave propagation. The first part consists in the description of the physics of multiphasic media (each phase and their interactions), using several upscaling methods, in order to obtain an equivalent mesoscale medium defined by seven parameters. Thus, in simple porosity saturated media and in complex media (double porosity, patchy saturation, visco-poroelasticity), I can compute seismic wave propagation without any approximation. Indeed, I use a frequency-space domain for the numerical method, which allows to consider all the frequency dependent terms. The spatial discretisation employs a discontinuous finite elements method (discontinuous Galerkin), which allows to take into account complex interfaces.The computation of the seismic attributes (velocities and attenuations) of complex porous media shows strong variations in respect with the frequency. Waveforms, computed without approximation, are strongly different if we take into account the full description of the medium or an homogenisation by averages. The last part of this work deals with the poroelastic parameters characterisation by inversion. For this, I develop a two-steps method: the first one consists in a classical inversion (tomography, full waveform inversion) of seismograms data to obtain macro-scale parameters (seismic attributes). The second step allows to recover, from the macroscale parameters, the poroelastic micro-scale properties. This downscaling step uses a semi-global optimisation method (neighbourhood algorithm), which allows the sampling of the full model space (thanks to the low numerical cost of the analytic direct model). With the a-priori knowledge of some parameters, a sensibility analysis shows that I can invert precisely skeleton parameters or the saturating fluid type, from the velocities only. Nevertheless, to recover the fluid saturation, it is preferable to use the attenuations. This two-steps procedure is tested on two realistic applications (reservoir monitoring and subsurface hydrogeophysics) and show that we can recover some constituve poroelastic parameters.La propagation des ondes sismiques dans les milieux poreux multiphasiques présente des enjeux nombreux, tant sur le plan environnemental (risques naturels, géotechnique, pollutions de nappes...) que pour les réservoirs (aquifères, hydrocarbures, stockages de CO2...). L'utilisation des ondes sismiques pour étudier ces milieux se justifie par le fait qu'en se propageant, les ondes sont déformées par le milieu qu'elles traversent et contiennent ainsi des informations aux capteurs sur les phases fluides et solides et sur le squelette poreux. Ce travail de thèse s'intéresse aux caractéristiques des ondes sismiques dans les milieux multiphasiques (plusieurs phases fluides et solides), depuis la description physique jusqu'à la caractérisation des paramètres constitutifs par inversion, en passant par la modélisation numérique 2D de la propagation. La première partie du travail a consisté à décrire la physique des milieux multiphasiques (phase par phase et leurs intéractions dynamiques) en utilisant des méthodes d'homogénéisation pour se ramener à un milieu équivalent défini par sept paramètres. Ainsi, dans des milieux simple porosité saturés et dans des milieux plus complexes (double porosité, partiellement saturés ou visco-poroélastiques), je peux calculer la propagation des ondes sismiques sans approximation. En effet, j'utilise une méthode numérique dans le domaine fréquence-espace qui permet de prendre en compte tous les termes qui dépendent de la fréquence sans approximation. La discrétisation spatiale utilise une méthode d'éléments finis discontinus (Galerkin discontinu) qui permet de considérer des milieux hétérogènes.Je montre notamment que les attributs sismiques (vitesses et atténuations) des milieux poreux complexes sont fortement dispersifs et les formes d'ondes complètes, calculées sans approximation, sont fortement dépendantes de la description physique du milieu. La caractérisation des paramètres poroélastiques s'effectue par inversion. Une méthode en deux étapes a été proposée : la première consiste en une inversion ``classique`` (tomographie, inversion des formes d'ondes complètes) des données (sismogrammes) pour obtenir des paramètres macro-échelles (attributs sismiques). La seconde étape permet de reconstruire, à partir des paramètres macro-échelles, les paramètres poroélastiques micro-échelles. Cette étape d'inversion utilise une méthode d'optimisation semi-globale (algorithme de voisinage). Une analyse de sensibilité montre qu'en connaissant a-priori certains paramètres, on peut inverser avec précision les paramètres du squelette poroélastique ou retrouver la nature du fluide saturant, à partir des vitesses de propagation. En revanche, pour retrouver la saturation en fluide, il est préférable de connaître les atténuations. Deux applications réalistes (monitoring de réservoir et hydrogéophysique) mettent en oeuvre ce type d'inversion en deux étapes et démontrent qu'à partir de données estimées par des méthodes classiques d'imagerie, on peut remonter à certains paramètres poroélastiques constitutifs

Using a Poroelastic Theory to Reconstruct Subsurface Properties: Numerical Investigation

International audienceThe quantitative imaging of the Earth subsurface is a major challenge in geophysics. In oil and gas exploration and production, aquifer management and other applications such as the underground storage of CO2 , seismic imaging techniques are implemented to provide as much information as possible on fluid-filled reservoir rocks. Biot theory (Biot, 1956) and its extensions provide a convenient framework to connect the various parameters characterizing a porous medium to the wave properties, namely, their amplitudes, velocities and frequency contents. The poroelastic model involves more parameters than the elastodynamic theory, but on the other hand, the wave attenuation and dispersion characteristics at the macroscopic scale are determined by the intrinsic properties of the medium without having to resort to empirical relationships

Geohazard Survey from Air (GEOSFAIR) - Report from field test at Fonnbu March 2022

I mars/april 2022 gjennomførte Statens vegvesen, Norges geotekniske institutt og SINTEF en felttest med UAS med ulike instrumenter på forskningsstasjonen Fonnbu i Stryn. Formålet med testen var å evaluere bruken av instrumenterte droner til overvåking og vurdering av snøskredfare. Instrumentene som ble testet inkluderte optisk og termisk avbildning, laserskanning og georadar. Resulterende datasett inkluderte 3D-modeller (punktskyer og høydekart), multispektrale og radiometriske, termiske bilder og radargrammer.In March/April 2022, the Norwegian Public Roads Administration, the Norwegian Geotechnical Institute and SINTEF performed a field test with UAS carrying different instruments at the research station Fonnbu in Stryn, Norway. The overall purpose was to evaluate the practical performance of UAS and sensors in field conditions towards the goal of assessing and monitoring snow avalanche hazard. The devices tested included optical and thermal imaging, laser scanning, and ground penetrating radar. Resulting geospatial datasets included 3D models (point clouds and elevation maps), multispectral and radiometric thermal images, and radargrams

Effects of sodium nitrite reduction, removal or replacement on cured and cooked meat for microbiological growth, food safety, colon ecosystem, and colorectal carcinogenesis in Fischer 344 rats

Epidemiological and experimental evidence indicated that processed meat consumption is associated with colorectal cancer risks. Several studies suggest the involvement of nitrite or nitrate additives via N-nitroso-compound formation (NOCs). Compared to the reference level (120 mg/kg of ham), sodium nitrite removal and reduction (90 mg/kg) similarly decreased preneoplastic lesions in F344 rats, but only reduction had an inhibitory effect on Listeria monocytogenes growth comparable to that obtained using the reference nitrite level and an effective lipid peroxidation control. Among the three nitrite salt alternatives tested, none of them led to a significant gain when compared to the reference level: vegetable stock, due to nitrate presence, was very similar to this reference nitrite level, yeast extract induced a strong luminal peroxidation and no decrease in preneoplastic lesions in rats despite the absence of NOCs, and polyphenol rich extract induced the clearest downward trend on preneoplastic lesions in rats but the concomitant presence of nitrosyl iron in feces. Except the vegetable stock, other alternatives were less efficient than sodium nitrite in reducing L. monocytogenes growth

Seismic wave propagation in heterogeneous multiphasic media : numerical modelling, sensibility and inversion of poroelastic parameters

La propagation des ondes sismiques dans les milieux poreux multiphasiques présente des enjeux nombreux, tant sur le plan environnemental (risques naturels, géotechnique, pollutions de nappes...) que pour les réservoirs (aquifères, hydrocarbures, stockages de CO2...). L'utilisation des ondes sismiques pour étudier ces milieux se justifie par le fait qu'en se propageant, les ondes sont déformées par le milieu qu'elles traversent et contiennent ainsi des informations aux capteurs sur les phases fluides et solides et sur le squelette poreux. Ce travail de thèse s'intéresse aux caractéristiques des ondes sismiques dans les milieux multiphasiques (plusieurs phases fluides et solides), depuis la description physique jusqu'à la caractérisation des paramètres constitutifs par inversion, en passant par la modélisation numérique 2D de la propagation. La première partie du travail a consisté à décrire la physique des milieux multiphasiques (phase par phase et leurs intéractions dynamiques) en utilisant des méthodes d'homogénéisation pour se ramener à un milieu équivalent défini par sept paramètres. Ainsi, dans des milieux simple porosité saturés et dans des milieux plus complexes (double porosité, partiellement saturés ou visco-poroélastiques), je peux calculer la propagation des ondes sismiques sans approximation. En effet, j'utilise une méthode numérique dans le domaine fréquence-espace qui permet de prendre en compte tous les termes qui dépendent de la fréquence sans approximation. La discrétisation spatiale utilise une méthode d'éléments finis discontinus (Galerkin discontinu) qui permet de considérer des milieux hétérogènes.Je montre notamment que les attributs sismiques (vitesses et atténuations) des milieux poreux complexes sont fortement dispersifs et les formes d'ondes complètes, calculées sans approximation, sont fortement dépendantes de la description physique du milieu. La caractérisation des paramètres poroélastiques s'effectue par inversion. Une méthode en deux étapes a été proposée : la première consiste en une inversion ``classique`` (tomographie, inversion des formes d'ondes complètes) des données (sismogrammes) pour obtenir des paramètres macro-échelles (attributs sismiques). La seconde étape permet de reconstruire, à partir des paramètres macro-échelles, les paramètres poroélastiques micro-échelles. Cette étape d'inversion utilise une méthode d'optimisation semi-globale (algorithme de voisinage). Une analyse de sensibilité montre qu'en connaissant a-priori certains paramètres, on peut inverser avec précision les paramètres du squelette poroélastique ou retrouver la nature du fluide saturant, à partir des vitesses de propagation. En revanche, pour retrouver la saturation en fluide, il est préférable de connaître les atténuations. Deux applications réalistes (monitoring de réservoir et hydrogéophysique) mettent en oeuvre ce type d'inversion en deux étapes et démontrent qu'à partir de données estimées par des méthodes classiques d'imagerie, on peut remonter à certains paramètres poroélastiques constitutifs.Seismic wave propagation in multiphasic porous media have various environmental (natural risks, geotechnics, groundwater pollutions...) and ressources (aquifers, oil and gas, CO2 storage...) issues. When seismic waves are crossing a given material, they are distorted and thus contain information on fluid and solid phases. This work focuses on the characteristics of seismic waves propagating in multiphasic media, from the physical complex description to the parameter characterisation by inversion, including 2D numerical modelling of the wave propagation. The first part consists in the description of the physics of multiphasic media (each phase and their interactions), using several upscaling methods, in order to obtain an equivalent mesoscale medium defined by seven parameters. Thus, in simple porosity saturated media and in complex media (double porosity, patchy saturation, visco-poroelasticity), I can compute seismic wave propagation without any approximation. Indeed, I use a frequency-space domain for the numerical method, which allows to consider all the frequency dependent terms. The spatial discretisation employs a discontinuous finite elements method (discontinuous Galerkin), which allows to take into account complex interfaces.The computation of the seismic attributes (velocities and attenuations) of complex porous media shows strong variations in respect with the frequency. Waveforms, computed without approximation, are strongly different if we take into account the full description of the medium or an homogenisation by averages. The last part of this work deals with the poroelastic parameters characterisation by inversion. For this, I develop a two-steps method: the first one consists in a classical inversion (tomography, full waveform inversion) of seismograms data to obtain macro-scale parameters (seismic attributes). The second step allows to recover, from the macroscale parameters, the poroelastic micro-scale properties. This downscaling step uses a semi-global optimisation method (neighbourhood algorithm), which allows the sampling of the full model space (thanks to the low numerical cost of the analytic direct model). With the a-priori knowledge of some parameters, a sensibility analysis shows that I can invert precisely skeleton parameters or the saturating fluid type, from the velocities only. Nevertheless, to recover the fluid saturation, it is preferable to use the attenuations. This two-steps procedure is tested on two realistic applications (reservoir monitoring and subsurface hydrogeophysics) and show that we can recover some constituve poroelastic parameters

Dataset of plugging and abandonment status from exploration wells drilled within the Troll gas and oil field in the Norwegian North Sea

More than 750 wildcat wells have been drilled in the Norwegian North Sea since 1966. Some of these wells could pose a risk for the environment, climate, and future CO2 and hydrogen storage projects by being potential leakage pathways for subsurface gases (mainly CH4 and stored CO2 and hydrogen). To ensure well integrity, these wells were secured by building cement plugs at crucial positions in the well path before abandoning the well. However, first 2004 the NORSOK d-010 standard defined strict regulation for plugging and abandonment (P&A) of gas and oil wells along the Norwegian continental margin. Here we report data relevant for the quality of a P&A work done on old exploration wells (1979 to 2003) from the Troll gas and oil field in the Norwegian North Sea. The data was extracted from public available well completion reports and the webpage of the Norwegian Petroleum Directorate. The dataset was analysed regarding their availability, plausibility and evaluated towards the present P&A regulations for offshore Norway. Based on twelve single criteria a final P&A score for 31 exploration wells was established, which may be applied to other abandoned wells in the Norwegian North Sea for further analyses. The resulting scores vary from -1 to 23.67 whereby lowest scores indicate wells where monitoring would be recommended. A P&A work evaluation is especially relevant in the Troll area as Norwegian large-scale CO2 storage is planned close to this location

Dataset of plugging and abandonment status from exploration wells drilled within the Troll gas and oil field in the Norwegian North Sea

More than 750 wildcat wells have been drilled in the Norwegian North Sea since 1966. Some of these wells could pose a risk for the environment, climate, and future CO2 and hydrogen storage projects by being potential leakage pathways for subsurface gases (mainly CH4 and stored CO2 and hydrogen). To ensure well integrity, these wells were secured by building cement plugs at crucial positions in the well path before abandoning the well. However, first 2004 the NORSOK d-010 standard defined strict regulation for plugging and abandonment (P&A) of gas and oil wells along the Norwegian continental margin. Here we report data relevant for the quality of a P&A work done on old exploration wells (1979 to 2003) from the Troll gas and oil field in the Norwegian North Sea. The data was extracted from public available well completion reports and the webpage of the Norwegian Petroleum Directorate. The dataset was analysed regarding their availability, plausibility and evaluated towards the present P&A regulations for offshore Norway. Based on twelve single criteria a final P&A score for 31 exploration wells was established, which may be applied to other abandoned wells in the Norwegian North Sea for further analyses. The resulting scores vary from -1 to 23.67 whereby lowest scores indicate wells where monitoring would be recommended. A P&A work evaluation is especially relevant in the Troll area as Norwegian large-scale CO2 storage is planned close to this location.publishedVersio

Propagation des ondes sismiques dans les milieux multiphasiques hétérogènes (modélisation numérique, sensibilité et inversion des paramètres poroélastiques)

La propagation des ondes sismiques dans les milieux poreux multiphasiques présente des enjeux nombreux, tant sur le plan environnemental (risques naturels, géotechnique, pollutions de nappes...) que pour les réservoirs (aquifères, hydrocarbures, stockages de CO2...). L'utilisation des ondes sismiques pour étudier ces milieux se justifie par le fait qu'en se propageant, les ondes sont déformées par le milieu qu'elles traversent et contiennent ainsi des informations aux capteurs sur les phases fluides et solides et sur le squelette poreux. Ce travail de thèse s'intéresse aux caractéristiques des ondes sismiques dans les milieux multiphasiques (plusieurs phases fluides et solides), depuis la description physique jusqu'à la caractérisation des paramètres constitutifs par inversion, en passant par la modélisation numérique 2D de la propagation. La première partie du travail a consisté à décrire la physique des milieux multiphasiques (phase par phase et leurs intéractions dynamiques) en utilisant des méthodes d'homogénéisation pour se ramener à un milieu équivalent défini par sept paramètres. Ainsi, dans des milieux simple porosité saturés et dans des milieux plus complexes (double porosité, partiellement saturés ou visco-poroélastiques), je peux calculer la propagation des ondes sismiques sans approximation. En effet, j'utilise une méthode numérique dans le domaine fréquence-espace qui permet de prendre en compte tous les termes qui dépendent de la fréquence sans approximation. La discrétisation spatiale utilise une méthode d'éléments finis discontinus (Galerkin discontinu) qui permet de considérer des milieux hétérogènes.Je montre notamment que les attributs sismiques (vitesses et atténuations) des milieux poreux complexes sont fortement dispersifs et les formes d'ondes complètes, calculées sans approximation, sont fortement dépendantes de la description physique du milieu. La caractérisation des paramètres poroélastiques s'effectue par inversion. Une méthode en deux étapes a été proposée : la première consiste en une inversion classique (tomographie, inversion des formes d'ondes complètes) des données (sismogrammes) pour obtenir des paramètres macro-échelles (attributs sismiques). La seconde étape permet de reconstruire, à partir des paramètres macro-échelles, les paramètres poroélastiques micro-échelles. Cette étape d'inversion utilise une méthode d'optimisation semi-globale (algorithme de voisinage). Une analyse de sensibilité montre qu'en connaissant a-priori certains paramètres, on peut inverser avec précision les paramètres du squelette poroélastique ou retrouver la nature du fluide saturant, à partir des vitesses de propagation. En revanche, pour retrouver la saturation en fluide, il est préférable de connaître les atténuations. Deux applications réalistes (monitoring de réservoir et hydrogéophysique) mettent en oeuvre ce type d'inversion en deux étapes et démontrent qu'à partir de données estimées par des méthodes classiques d'imagerie, on peut remonter à certains paramètres poroélastiques constitutifs.Seismic wave propagation in multiphasic porous media have various environmental (natural risks, geotechnics, groundwater pollutions...) and ressources (aquifers, oil and gas, CO2 storage...) issues. When seismic waves are crossing a given material, they are distorted and thus contain information on fluid and solid phases. This work focuses on the characteristics of seismic waves propagating in multiphasic media, from the physical complex description to the parameter characterisation by inversion, including 2D numerical modelling of the wave propagation. The first part consists in the description of the physics of multiphasic media (each phase and their interactions), using several upscaling methods, in order to obtain an equivalent mesoscale medium defined by seven parameters. Thus, in simple porosity saturated media and in complex media (double porosity, patchy saturation, visco-poroelasticity), I can compute seismic wave propagation without any approximation. Indeed, I use a frequency-space domain for the numerical method, which allows to consider all the frequency dependent terms. The spatial discretisation employs a discontinuous finite elements method (discontinuous Galerkin), which allows to take into account complex interfaces.The computation of the seismic attributes (velocities and attenuations) of complex porous media shows strong variations in respect with the frequency. Waveforms, computed without approximation, are strongly different if we take into account the full description of the medium or an homogenisation by averages. The last part of this work deals with the poroelastic parameters characterisation by inversion. For this, I develop a two-steps method: the first one consists in a classical inversion (tomography, full waveform inversion) of seismograms data to obtain macro-scale parameters (seismic attributes). The second step allows to recover, from the macroscale parameters, the poroelastic micro-scale properties. This downscaling step uses a semi-global optimisation method (neighbourhood algorithm), which allows the sampling of the full model space (thanks to the low numerical cost of the analytic direct model). With the a-priori knowledge of some parameters, a sensibility analysis shows that I can invert precisely skeleton parameters or the saturating fluid type, from the velocities only. Nevertheless, to recover the fluid saturation, it is preferable to use the attenuations. This two-steps procedure is tested on two realistic applications (reservoir monitoring and subsurface hydrogeophysics) and show that we can recover some constituve poroelastic parameters.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Estimation of rock physics properties from seismic attributes - Part 1: Strategy and sensitivity analysis

The quantitative estimation of rock physics properties is of great importance in any reservoir characterization. We have studied the sensitivity of such poroelastic rock physics properties to various seismic viscoelastic attributes (velocities, quality factors, and density). Because we considered a generalized dynamic poroelastic model, our analysis was applicable to most kinds of rocks over a wide range of frequencies. The viscoelastic attributes computed by poroelastic forward modeling were used as input to a semiglobal optimization inversion code to estimate poroelastic properties (porosity, solid frame moduli, fluid phase properties, and saturation). The sensitivity studies that we used showed that it was best to consider an inversion system with enough input data to obtain accurate estimates. However, simultaneous inversion for the whole set of poroelastic parameters was problematic due to the large number of parameters and their trade-off. Consequently, we restricted the sensitivity tests to the estimation of specific poroelastic parameters by making appropriate assumptions on the fluid content and/or solid phases. Realistic a priori assumptions were made by using well data or regional geology knowledge. We found that (1) the estimation of frame properties was accurate as long as sufficient input data were available, (2) the estimation of permeability or fluid saturation depended strongly on the use of attenuation data, and (3) the fluid bulk modulus can be accurately inverted, whereas other fluid properties have a low sensitivity. Introducing errors in a priori rock physics properties linearly shifted the estimations, but not dramatically. Finally, an uncertainty analysis on seismic input data determined that, even if the inversion was reliable, the addition of more input data may be required to obtain accurate estimations if input data were erroneous

Offset dependence of overburden time-shifts from ultrasonic data

Depletion or injection into a reservoir implies stress changes and strains in the reservoir and its surroundings. This may lead to measurable time-shifts for seismic waves propagating in the subsurface. To better understand the offset dependence of time-shifts in the overburden, we have systematically quantified the time-shifts of three different overburden shales in controlled laboratory tests. These experiments may be viewed as an analogue to the time-shifts recorded from seismic field surveys. For a range of different stress paths, i.e. the ratio between the horizontal and the vertical stress changes, the changes of the P-wave velocities in different directions were measured such that the offset dependence of time-shifts for different stress paths could be studied. The time-shifts are stress path dependent, which is particularly pronounced at large offsets. For all stress paths the time-shifts exhibit a linearly decreasing trend with increasing offset, i.e. a negative offset-gradient. At zero offset, for which the ray path is normal to the bedding, the time-shifts are similar for all investigated stress paths. The isotropic stress path is associated with the smallest offset-gradient of the time-shifts. Contrary, the constant-mean-stress path shows the largest gradient with a flip in the polarity of the time-shifts for the largest offsets. The separate contributions from the strain and velocity changes to the time-shift were also quantified. The time-shifts for the isotropic stress path are dominated by the contribution from velocity changes at all offsets. Contrary, the strain contributes significantly to the time-shifts at small offsets for the constant-mean-stress path. This shows that the offset dependence in pre-stack seismic data may be a key to understand the changes of subsurface stresses, pore pressure and strain upon depletion or injection. To utilize this knowledge from laboratory experiments, calibrated rock physics models and correlations are needed to constrain the seismic time-shifts and to obtain an adequately updated geological model reflecting the true anisotropic nature of the subsurface. This may have important implications for improved recovery and safety, particularly in mature fields.publishedVersio