Oxand SA

Fontainebleau, France
Fontainebleau, France
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Guen Y.L.,OXAND S.A. | Huot M.,OXAND S.A. | Loizzo M.,Schlumberger | Poupard O.,OXAND S.A.
Energy Procedia | Year: 2011

Given the global interest in reducing greenhouse gas emissions, the 18 member CO2Sink consortium was formed to develop a pilot CO 2 sequestration project near the town of Ketzin, Germany to advance the knowledge and understanding of CCS as a method of reducing CO2 emissions. This project includes 2 monitoring wells and 1 injection well, for a total injection of 30,000 tonnes of CO2. Among the projects associated with the Ketzin injection site, the COSMOS 2 research project was initiated as a partnership between France and Germany. The project includes, among others activities, the evaluation of the injection well (Ktzi-201) integrity. This was performed through extensive modeling using P&R™ approach and SIMEO™ Stor platform to simulate possible CO2 leakage along the wellbore over a 1,000-year period and a resulting risk assessment. Various case studies were tested: whereas risk levels tend to be low for a pilot project (i.e. low CO2 reservoir pressure), treatment actions could be required for industrial scale projects (i.e. greater CO2 reservoir pressure), such as additional characterizations, workovers, or an advanced abandonment strategy. These actions could decrease either the probability of the risk, or the severity, or both, ensuring effective CO2 confinement demonstration over the long-term. This study provides objective support in decisions regarding well management of the CO2 Ketzin project. © 2010 Elsevier Ltd. © 2011 Published by Elsevier Ltd.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2008.5.2.4 | Award Amount: 10.56M | Year: 2009

The objectives of MUSTANG are to develop and disseminate a comprehensive set of methodologies and tools for the assessment and characterization of deep saline aquifers for CO2 storage, providing measures of performance and risk that are necessary for a cost-benefit analysis, ensuring public confidence and acceptance and promoting its deployment. Novel CO2 storage specific field investigation technologies and methodologies will be developed, allowing an improved determination of the relevant physical properties of the site and enabling short response times in the detection and monitoring of CO2 plumes during both the injection and storage phases. We also aim at an improved understanding of the processes of CO2 spreading by means of theoretical investigations, laboratory experiments, natural analogue studies and field scale injection tests, including those relevant to the 1) seal integrity; 2) the negative impact of possibly conductive faults; 3) formation heterogeneities; 4) CO2 trapping mechanisms; and 5) effective treatment for the wide span of spatial and temporal scales of the coupled thermo-hydro-mechanical-chemical processes. Based on the improved process models, conceptual and numerical models will be developed for analyzing CO2 injection and storage and implemented at six test sites representing different geological settings and geographical locations in Europe, also addressing the impact of the CO2 injection on seal integrity. The guidelines to be developed will be integrated into a decision support system, which will include a risk assessment component and liabilities consideration. The DSS will be tested and validated at the various project test sites. Special attention has been devoted to promote measures capable of enhancing public outreach and acceptance and dissemination of the methodologies and technologies to the wide public.

Idiart A.,AMPHOS 21 Consulting S.L. | Idiart A.,OXAND S.A. | Bisschop J.,ETH Zurich | Caballero A.,BBR VT International | And 2 more authors.
Cement and Concrete Research | Year: 2012

Aggregates in cementitious composites subject to drying lead to mechanical restraint of the matrix shrinkage, which under certain conditions may lead to internal microcracking. In the present work this phenomenon is investigated using a two-dimensional (2D) numerical model and an approximate 2D experimental approach. Experimental and simulated samples with simplified and matching spatial aggregate distributions were produced to make a quantitative comparison between experiments and model predictions. In particular, the effects of aggregate size and volume fraction on the degree of internal microcracking are assessed. The main challenges of performing a quantitative comparison are highlighted and discussed. These are related to: (i) the difficulty of designing experiments without moisture gradient effects; (ii) the experimental crack detection limit; and (iii) the role of the creep response of the matrix phase in the model. The results suggest the existence of a critical aggregate size below which aggregate-restraint does not cause detectable microcracking. © 2011 Elsevier Ltd. All rights reserved.

Schoefs F.,University of Nantes | Boero J.,Oxand S.A | Clement A.,Oxand S.A | Capra B.,Oxand S.A
Structure and Infrastructure Engineering | Year: 2012

Owners of civil infrastructure base their maintenance decision schemes mainly on both structural integrity assessment and consequence analysis. Some inputs come from information collected by inspections with non-destructive or destructive tools. Uncertainties and errors of measurement can lead to bad decisions but are rarely integrated into the decision process. Currently, risk-based inspection (RBI) provides the basic concepts for optimising the maintenance plans of existing structures while insuring satisfactory safety and availability of the structure during its service life. It relies both on reliability computations and probabilistic modelling of inspection results. This last point leads to introduce the probability of detection and the probability of false alarms that are usually considered as parameters in RBI. However, when data from inter-calibration campaigns are available, the whole receiver operating characteristics curves should be used. Then, the comparison of non-destructive testing tools in terms of cost or benefit is difficult as well as the method for optimising a given technique. This article presents the αβ method that gives a new performance indicator in this context. It is applied to the field of inspection of harbour structures. © 2012 Taylor and Francis.

Laudet J.-B.,Total S.A. | Garnier A.,Total S.A. | Neuville N.,OXAND SA | Le Guen Y.,OXAND SA | And 4 more authors.
Energy Procedia | Year: 2011

One of the major technological issues for CO2 injection is the long-term behavior of the cement-based materials used to ensure the overall sealing performance of the storage wells. When water is present, the CO 2 injected can react chemically with the cement (i.e. carbonation). The objectives of our experimental program are to assess the kinetics and phenomenology of the changes that occur in class-G Portland cements exposed to CO2-enriched aqueous fluids at 8 MPa and two different temperatures (90°C and 140°C). The experimental program presented in this paper consists of two carbonation tests (static tests) and a coupled chemo-mechanical test (dynamic test) which were performed on similar class-G cement and similar CO2-rich water. The main preliminary results show a carbonation front progressing from the fluid-sample interface towards the sample centre. The front moves faster at 140°C than 90°C because of the different carbonation process involved at this higher temperature. The results of a coupled chemo-mechanical test with injection of CO2-saturated water show that the CO2 flow rate in the cement rapidly decreases, finally resulting in carbonation clogging of the cement sample. They seem consistent with reported field observations. © 2010 Elsevier Ltd. © 2011 Published by Elsevier Ltd.

Dias S.,OXAND S.A. | Guen Y.L.,OXAND S.A. | Poupard O.,OXAND S.A. | Shtivelman V.,Geophysical Institute of Israel
Energy Procedia | Year: 2011

One of the work packages of MUSTANG (MUltiple Space and Time scale Approach for the quaNtification of deep saline formations for CO2 storaGe) EU project is dedicated to developing a generic methodology for risk assessment related to CO2 in saline aquifers and applying the methodology to an experimental site. This paper presents the work done by OXAND regarding risk assessment and the application of a risk-based approach to the qualification of the storage site ultimately to provide guidelines for further industrial storage projects. The risk assessment process is presented, and illustrated with the data of an experimental site. The eight steps of the risk assessment process highlighted in the ISO 31000 are described in this paper: risk management policy, establishment of the context, risk identification, risk estimation, risk evaluation, risk treatment, communication and consultation, and monitoring and review. © 2010 Elsevier Ltd. © 2011 Published by Elsevier Ltd.

Idiart A.E.,OXAND S.A. | Lopez C.M.,University of Barcelona | Carol I.,University of Barcelona
Cement and Concrete Composites | Year: 2011

In this paper we focus on the external sulfate attack on concrete specimens at the meso-level. There is nowadays a renewed interest in rationally describing the mechanisms behind expansive processes leading to cracking and spalling of concrete exposed to sulfate solutions. A model is presented for degradation of concrete exposed to external sulfate attack at the meso-level, i.e. representing explicitly in the simulations the main heterogeneities of the material. A previously developed mesomechanical approach has been coupled with a diffusion-reaction analysis at the same scale. It is based on the systematic use of zero-thickness interface elements equipped with fracture-based constitutive laws, and the effect of discrete cracks on the transport of ions is explicitly accounted for. The main results obtained agree qualitatively and quantitatively well with experimental observations in terms of ettringite penetration depth, expansions, crack patterns and spalling effects. © 2011 Published by Elsevier Ltd.

Idiart A.E.,OXAND S.A. | Lopez C.M.,University of Barcelona | Carol I.,University of Barcelona
Materials and Structures/Materiaux et Constructions | Year: 2011

In this paper, an existing mesomechanical model for cementitious materials is extended to the domain of diffusion-driven phenomena. The model is based on the Finite Element Method, and uses zero-thickness interface elements equipped with a fracture-based constitutive formulation to represent cracks. The new developments presented in this paper consist of the application of the model to the hygro-mechanical coupled analysis of drying shrinkage in concrete specimens, explicitly taking into account the influence of (micro) cracks on the diffusion of moisture. In a first part of the paper, the model is presented in some detail, especially the new aspects regarding moisture diffusion including effects of cracks, and H-M coupling. The model predictions are then quantitatively compared with classical drying shrinkage experiments on concrete specimens. The consideration of different assumptions for the relation linking shrinkage strains and weight losses is discussed in some detail. Finally, the effect of size and volume fraction of the main heterogeneities of concrete on the drying process and drying-induced microcracking is also addressed. © 2010 RILEM.

Boero J.,OXAND S.A. | Schoefs F.,University of Nantes | Yanez-Godoy H.,OXAND S.A. | Capra B.,OXAND S.A.
European Journal of Environmental and Civil Engineering | Year: 2012

This article summarises research led during the second phase of the French GEROM (risk management of maritime and river harbour structures) project in order to quantify the risks associated with vulnerable structures. A reliability analysis is applied here to steel sheet-pile seawalls. For this purpose, a stochastic (spatial-temporal) model of steel corrosion is proposed, based on a statistical analysis of data collected from wharves located in several French ports and of various ages. The predictions obtained from the corrosion model are then integrated into a reliability analysis to carry out a time-function reliability analysis of corroded harbour structures. The results are then compared and analysed both in terms of reliability and sensitivity to basic random variables. This approach allows suggesting preliminary requirements about maintenance optimisation. © 2012 Taylor & Francis.

Asamoto S.,Saitama University | Le Guen Y.,Oxand SA | Poupard O.,Oxand SA | Capra B.,Oxand SA
Engineering Computations (Swansea, Wales) | Year: 2013

Purpose - In the carbon dioxide capture and storage (CCS) project, the integrity of CO2 injection wells plays a vital role in the long-term safety of CO2 storage. The authors aim to practically investigate possible CO2 leakage of a CO2 injection well section during the injection operation and shut-in by the thermomechanical FEM simulation. The application of numerical simulation to the CO2 injection well deep underground is the first step that will help in the quantitative evaluation of the mechanical risks. Design/methodology/approach - The injection of CO2 at a temperature different from those of the well and the surrounding geological formation is likely to cause different thermal deformations of constitutive well materials. This could lead to cement cracking and microannuli openings at the interfaces of different materials such as casing/cement and cement/rock. In this paper, the possibility and order of magnitude of cement cracking and microannuli creation in the cross section of the well are assessed from a numerical case study within a classical thermomechanical finite element model framework. Findings - The possibility of compressive failure and tensile cracking in the cement of the studied wells due to CO2 injection is small unless a large casing eccentricity or an initial defect in the cement is present. Some microannuli openings are generated at interfaces cement/casing and/or cement/rock during the CO2 injection because of different thermal shrinkage of each material. However, the width is not important enough to cause significant CO2 leakage under the studied conditions. The use of "flexible" cement especially developed for oil well applications could mitigate the risk of cement cracking during CO2 injection. Originality/value - Numerous experimental studies on the chemical deterioration of the cement under severe conditions have been carried out. On the other hand, only a few investigations have focused on the mechanical behavior under thermal/pressure changes related to CO2 injection. In this paper, the quantitative analysis to investigate cement cracking and microannuli formation is achieved to help in the identification of possible mechanical defects to cause CO2 leakage. In addition, the discussion about the risk of the possible casing eccentricity and the application of flexible cement in the oil and gas field to CO2 injection well could be practically useful. © Emerald Group Publishing Limited.

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