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William Carey J.,Los Alamos National Laboratory | Svec R.,New Mexico Institute of Mining and Technology | Grigg R.,New Mexico Institute of Mining and Technology | Zhang J.,Los Alamos National Laboratory | Crow W.,BP Alternative Energy
International Journal of Greenhouse Gas Control | Year: 2010

Wellbore integrity is one of the key performance criteria in the geological storage of CO2. It is significant in any proposed storage site but may be critical to the suitability of depleted oil and gas reservoirs that may have 10's to 1000's of abandoned wells. Much previous work has focused on Portland cement which is the primary material used to seal wellbore systems. This work has emphasized the potential dissolution of Portland cement. However, an increasing number of field studies (e.g., Carey et al., 2007), experimental studies (e.g., Kutchko et al., 2006) and theoretical considerations indicate that the most significant leakage mechanism is likely to be flow of CO2 along the casing-cement microannulus, cement-cement fractures, or the cement-caprock interface. In this study, we investigate the casing-cement microannulus through core-flood experiments. The experiments were conducted on a synthetic wellbore system consisting of a 5-cm diameter sample of cement that was cured with an embedded rectangular length of steel casing that had grooves to accommodate fluid flow. The experiments were conducted at 40° C and 14 MPa pore pressure for 394 h. During the experiment, 6.2 l of a 50:50 mixture of supercritical CO2 and 30,000 ppm NaCl-rich brine flowed through 10-cm of limestone before flowing through the 6-cm length cement-casing wellbore system. Approximately 59,000 pore volumes of fluid moved through the casing-cement grooves. Scanning electron microscopy revealed that the CO2-brine mixture impacted both the casing and the cement. The Portland cement was carbonated to depths of 50-250μ m by a diffusion-dominated process. There was very little evidence for mass loss or erosion of the Portland cement. By contrast, the steel casing reacted to form abundant precipitates of mixed calcium and iron carbonate that lined the channels and in one case almost completely filled a channel. The depth of steel corroded was estimated at 25- 30 μm and was similar in value to results obtained with a simplified corrosion model. The experimental results were applied to field observations of carbonated wellbore cement by Carey et al. (2007) and Crow et al. (2009) to show that carbonation of the field samples was not accompanied by significant CO2-brine flow at the casing-cement interface. The sensitivity of standard-grade steel casing to corrosion suggests that relatively straight-forward wireline logging of external casing corrosion could be used as a useful indicator of flow behind casing. These experiments also reinforce other studies that indicate rates of Portland cement deterioration are slow, even in the high-flux CO2-brine experiments reported here. © 2009 Elsevier Ltd. All rights reserved.


Woods A.W.,University of Cambridge | Espie T.,BP Alternative Energy
Geophysical Research Letters | Year: 2012

Sequestration of carbon dioxide in deep saline aquifers has been proposed and investigated as a viable solution to help mitigate carbon emissions from fossil fuels. Much research has been directed at understanding the transitions of supercritical CO2 from being a mobile fluid phase to being trapped by capillarity or dissolved in groundwater; such transitions lead to a reduction in mobility of CO2 and hence in the risk of leakage to the surface. Following injection, buoyant plumes of CO2 migrate updip towards structural traps in the geological strata; however, some of this CO 2 may be capillary trapped in pore spaces or dissolved in groundwater en route. Since CO2 saturated groundwater only has a small CO 2 concentration, the dissolution of any large, structurally trapped plumes of CO2 may be controlled by the availability of unsaturated groundwater. In an aquifer of finite vertical extent, this may be rate limited by a combination of (i) the background hydrological flow coupled with (ii) the slow lateral exchange of relatively dense, CO2 saturated groundwater with unsaturated groundwater. In an inclined aquifer, this may be controlled by the slow along-aquifer component of gravity. Structurally trapped plumes of CO2 may therefore persist for many thousands of years, and, since they are potentially highly mobile, may represent an important contribution to the long term risks associated with CO2 sequestration at particular sites. © 2012 by the American Geophysical Union.


A European/Chinese consortium has commenced the next phase of a carbon dioxide capture technology research effort aimed at developing innovative and low-cost technologies for power generation with pre-combustion carbon dioxide capture. Known as CACHET-II, this European Commission-funded project is an international consortium of academia and business, which aims to develop innovative membrane reactors to increase the energy efficiency of pre-combustion carbon dioxide capture in natural gas- and coal-fired power plants. Membranes can combine the efficient conversion of fuel into hydrogen for large-scale power production with capture of the remaining carbon dioxide in one reactor. The membrane reactor can be integrated into a combined power cycle, the hydrogen being used as fuel for power generation. The remaining stream contains mainly carbon dioxide and some non-recovered hydrogen and steam. Subsequent condensation of the steam leaves concentrated carbon dioxide at high pressure, reducing the compression energy for transport and storage. © 2011 Published by Elsevier Ltd.


Beavis R.,BP Alternative Energy
Energy Procedia | Year: 2011

After 3 years and over one thousand person-months of effort, the FP6 CACHET project was successfully concluded in the first half of 2009. CACHET focussed on pre-combustion capture of carbon dioxide (CO2) from natural gas fuelled power generation and hydrogen (H2) production. Through a combination of experimental and paper studies, CACHET developed, optimised and evaluated four promising capture technologies: Advanced steam methane reforming (HyGenSys), Redox technologies (chemical looping), Metal membranes and Sorption enhanced water gas shift (SEWGS). This paper reports the technical and economic conclusions of the project and provides a look ahead to the future for each of the technologies and the challenges for full scale deployment. All technologies showed the potential to reduce CO2 emissions by more than 90% and the opportunity to improve the energy efficiency compared to the state-of-the-art technology. © 2011 Published by Elsevier Ltd.


Grant
Agency: GTR | Branch: Innovate UK | Program: | Phase: Collaborative Research & Development | Award Amount: 347.17K | Year: 2010

This project will deliver new, leading-edge sensor and measurement technologies to monitor and assess the efficiency and safety of carbon capture, transport, injection and storage to comply with EU regulation. Carbon Capture and Storage is a key accessible climate change mitigation measure which will enable current carbon based power production to continue, while reducing climate impact. There is a need for substantial new measurement capability to validate estimates of CO2 losses from individual stages of the process. The overall aim for the project is to develop a suite of advanced CO2 sensing technologies that combine to provide validated monitoring of each stage of the CCS process.Infra red cameras currently manufactured will be developed further to provide a quantification function to measure large point source carbon dioxide leaks. The National Physical Laboratory (NPL) tunable diode laser spectrometer, which measures atmospheric carbon dioxide concentrations accurately, will be redesigned to measure small changes in atmospheric carbon dioxide concentrations, typical of those which might arise from leaks in an underground storage facility. Signal Group will develop new processing software and refine instrument parameters on their continuous emissions monitors to quantify residual carbon dioxide remaining after the capture process.

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