Random packings of spiky particles : Geometry and transport properties

Spiky particles are constructed by superposing spheres and prolate ellipsoids. The resulting nonconvex star particles are randomly packed by a sequential deposition algorithm. The geometry, the conductivity, and the permeability of the resulting packings are systematically studied, in relation with the individual grain characteristics. Overall correlations are proposed to approximate these properties as functions of the grain equivalent size and sphericity index

Acoustic properties of saturated porous media

This work addresses the propagation of acoustic waves in porous media. The theoretical developments or earlier works are generalized to establish dynamic poro-elastic equations for a compressible fluid in a pore space which may consist in multiple independent pore components, closed or percolating. These equations involve several effective coefficients, to be determined by solving closure problems on the microscale. Systematic applications are presented, for various kinds of model reconstructed media, and for real media imaged by microtomography

Acoustic wave propagation in the heterogeneous media

Les propriétés acoustiques des milieux poreux sont étudiées dans le cadre général de la théorie de l'homogénéisation, en supposant que l'échelle caractéristique des pores est petite devant la longueur d'onde, en appliquant les développemennts succéssifs du formalisme de Boutin et Auriault (1993). Pour les milieux secs, on détermine la célérité d'une onde plate (de compression ou de cisaillement), et éventuellement la correction de polarisation, la dispersion de célérité ainsi que l'atténuation due à la diffraction de Rayleigh. Différents types de milieux modèles ainsi que des matériaux réels imagés par microtomographie X sont étudiés. Dans les milieux poreux saturés, le comportement acoustique est décrit par une équation de type élastique dans la phase solide et par les équations de Navier-Stokes dans le fluide interstitiel. La perméabilité dynamique et les les célérités des ondes de compression et de cisaillement sont déterminées pour les mêmes milieux que précédemmentThe acoustic properties of porous media are addressed in the general framework of homogenization theory, by assuming that the typical pore scale is small compared to the wave length, and by applying the successive expansions of the formalism of Boutin and Auriault (1993). For dry media, the celerity of plane compressive or shear waves can be determined, as well as the correction to polarization, the celerity dispersion and the attenuation due to Rayleigh scattering. Various kinds of model media are studied, and a few real materials which have been characterized by Xray microtomography. In saturated media, the acoustic behavior is governed by the elastic equations in the solid phase and by the Navier-Stokes equations in the interstitial fluid. The dynamic permeability and the compressive and shear wave celerities are determined for the same media as in the dry casePARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Sci.Terre recherche (751052114) / SudocSudocFranceF

Impact of geomechanical effects during SAGD process in a meander belt

In the reservoir simulations, the geomechanical effects are usually taken into account to describe the porosity and the permeability variations. In this paper, we present a new method, patented by authors, which allows to model the geomechanical effects also on the well productivity index. The Steam Assisted Gravity Drainage (SAGD) method is widely used for the heavy oil production. A very high variation in pressure and temperature play a significant role on the petrophysical properties and may impact the productivity estimation. In this paper we develop a new simplified geomechanical model in order to account for the thermal and pressure effects on the porosity, permeability and the productivity index during the reservoir simulation. At the current state, these dependencies are defined using semi-analytical relationships. The model is applied to a meandering fluvial reservoir based on 3D outcrop observations. The productivity is found underestimated if the pressure and temperature effects on the petrophysical properties are ignored in the reservoir simulation. Moreover, this study shows an important impact of thermal effects on the productivity estimation. The results of this work show that it is essential to properly take into account the geomechanical effects on the petrophysical properties and also on the productivity index for a better productivity estimation

Impact of geomechanical effects during SAGD process in a meander belt

In the reservoir simulations, the geomechanical effects are usually taken into account to describe the porosity and the permeability variations. In this paper, we present a new method, patented by authors, which allows to model the geomechanical effects also on the well productivity index. The Steam Assisted Gravity Drainage (SAGD) method is widely used for the heavy oil production. A very high variation in pressure and temperature play a significant role on the petrophysical properties and may impact the productivity estimation. In this paper we develop a new simplified geomechanical model in order to account for the thermal and pressure effects on the porosity, permeability and the productivity index during the reservoir simulation. At the current state, these dependencies are defined using semi-analytical relationships. The model is applied to a meandering fluvial reservoir based on 3D outcrop observations. The productivity is found underestimated if the pressure and temperature effects on the petrophysical properties are ignored in the reservoir simulation. Moreover, this study shows an important impact of thermal effects on the productivity estimation. The results of this work show that it is essential to properly take into account the geomechanical effects on the petrophysical properties and also on the productivity index for a better productivity estimation

Analysis of Surface Movement through Conceptual and Coupled Flow-Geomechanics Models an Example of Surface Monitoring Assessment for CCS Project

Monitoring of geological CO2 storage sites is crucial for the widespread deployment of this technology to be accepted as a reliable method of reducing CO2 emissions worldwide. The SENSE project aims to develop reliable, continuous and cost-effective monitoring based on ground motion detection combined with modelling and geomechanical inversion, using new technological developments, data processing optimization and interpretation algorithms. In this context, we present a methodology based on coupled flow/geomechanical simulations which, from the uncertainty on the subsurface properties and uncertainties on the measurements, can reproduce the measurements from different surface monitoring tools. By carrying out an uncertainty study on simulations results and taking into account the advantages and disadvantages of each of these tools, a monitoring strategy can be designed such that the tools will record potential displacements at the most sensitive periods and locations, taking into account their respective accuracies. If surface displacements are measurable and sufficiently sensitive to subsurface properties then this kind of monitoring will help to better constrain subsurface properties and possibly subsurface behavior such as plume migration, pressure propagation, and storage capacity. This methodology is applied to conceptual models in order to identify which conditions induce different surface displacements and thus may require specific surface monitoring strategy