Category Energy Portfolio


Bertrand Barre & Philippe Garderet AREVA, Paris Cedex, France

5.3.1 Introduction

France is a medium size country of 63 million inhabitants, blessed with a mild climate favourable to agriculture, various beautiful landscapes and a long cultural and archi­tectural inheritance – not to mention its well-established tradition of gastronomy – which make it the number one tourist destination. However, in terms of fossil energy resources, France is poor: very little oil and almost no coal and gas left.

It is the main reason why France has been, for now nearly 40 years, developing an intensive electro nuclear program. This program covers the entire industrial cycle (nuclear plants but also all the various stages of nuclear fuel cycle)...

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Legal issues

States can regulate subsurface injection and storage of CO2 within their jurisdiction in accordance with their national rules and regulations. Such rules and regulations could be provided by the mining laws, resource conservation laws, laws on drinking water, waste disposal, oil and gas production, treatment of high-pressurized gases, and others. An analysis of existing regulations in North America, Europe, Japan, and Australia highlights the lack of regulations that are specifically relevant for CO2 stor­age and the lack of clarity relating to post-injection responsibilities (IEA Greenhouse Gas R&D Programme, 2003; IOGCC, 2005).

In the U. S.A., the Safe Drinking Water Act regulates most underground injection activities. The U. S...

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Risk management

Risk management entails the application of a structured process to identify and quan­tify the risks associated with a given process, to evaluate these, taking into account stakeholder input and context, to modify the process to remove excess risks, and to identify and implement appropriate monitoring and intervention strategies to manage the remaining risks.

For geological storage, effective risk mitigation consists of four interrelated activities:

• Careful site selection, including performance and risk assessment, and socio­economic and environmental factors

• Monitoring to provide assurance that the storage project is performing as expected and to provide early warning in the event that it begins to leak

• Effective regulatory oversight

• Implementation of remediation measures t...

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Potential hazards to human health and safety

Risks to human health and safety arise (almost) exclusively from elevated CO2 con­centrations in ambient air, either in confined outdoor environments, in caves, or in buildings. Physiological and toxicological responses to elevated CO2 concentrations are relatively well understood. At concentrations above ~2%, CO2 has a strong effect on respiratory physiology, and at concentrations above 7-10%, it can cause uncon­sciousness and death. Exposure studies have not revealed any adverse health effect of chronic exposure to concentrations below 1%...

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Processes and pathways for release of CO2 from geological storage sites

Carbon dioxide that exists as a separate phase (supercritical, liquid, or gas) may escape from formations used for geological storage through the following pathways:

1 Through the pore system in low-permeability caprocks such as mudstones, if the capillary entry pressure at which CO2 may enter the caprock is exceeded

2 Through openings in the caprock or fractures and faults

3 Through man-made pathways, such as poorly completed and/or abandoned pre-existing wells.

For onshore storage sites, CO2 that has leaked may reach the water table and migrate into the overlying vadose zone. This occurrence would likely include CO2 contact with drinking-water aquifers...

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Environmental impacts, risks, and risk management

The environmental impacts arising from geological storage fall into two broad catego­ries: local environmental effects and global effects arising from the release of stored CO2 to the atmosphere. Global effects may alternatively be viewed as uncertainty in the effectiveness of CO2 storage. Local health, safety, and environmental hazards arise from three distinct causes:

– The direct effects of elevated gas-phase CO2 concentrations in the shallow subsur­face and near-surface environment

– The effects of dissolved CO2 on groundwater chemistry

– The effects that arise from the displacement of fluids by the injected CO2

Risks are proportional to the magnitude of the potential hazards and the prob­ability that these hazards will occur...

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Monitoring and verification technology

Monitoring is needed for a wide variety of purposes. Specifically, monitoring can be

used to:

– Ensure and document effective injection well controls, specifically for monitoring the condition of the injection well and measuring injection rates, wellhead, and formation pressures. Petroleum industry experience suggests that leakage from the injection well itself, resulting from improper completion or deterioration of the casing, packers, or cement, is one of the most significant potential failure modes for injection projects (Perry, 2005; Apps, 2005).

– Verify the quantity of injected CO2 that has been stored by various mechanisms, such as depicted in Figure 5.2.4.

– Optimize the efficiency of the storage project, including utilization of the storage volume, injection pressures and drilling...

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Technical background

Injection well technologies

Many of the technologies required for large-scale geological storage of CO2 already ex­ist. Drilling and completion technology for injection wells in the oil and gas industry has evolved to a highly sophisticated state, such that it is now possible to drill and complete vertical and extended reach wells (including horizontal wells) in deep formations, wells with multiple completions, and wells able to handle corrosive fluids. Based on extensive oil industry experience, the technologies for drilling, injection, stimulations, and com­pletions for CO2 injection wells exist and are being practiced with some adaptations in current CO2 storage projects...

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