Experimental and numerical modeling of CO₂ leakage in the vadose zone

Abstract

This study presents the experimental and modeling results of CO2 injection and transport in the vadose zone performed in PISCO2 facilities at the ES.CO2 center in Ponferrada (North Spain). During 46 days of experiments, 62.10 kg of CO2 were injected through 16 micro‐injectors in a 35 m3 experimental unit filled with sandy material. Monitoring and mapping of surface CO2 flux were performed periodically to assess the evolution of CO2 migration through the soil and to the atmosphere. Numerical simulations were run using TOUGH2 code with EOS7CA research module considering two phases (gas and liquid) and three components (H2O, CO2, air). Two layers (sand, gravel) and atmosphere boundary were implemented taking into account heterogeneous soils, homogeneous soil, rainfall, temperature, and liquid saturation to allow a better understanding of CO2 behavior in the vadose zone. This combined experimental and modeling approach shows that CO2 leakage in the vadose zone quickly comes out through preferential migration pathways and spots with the ranges of fluxes in the ground/surface interface from 2.5 to 600 g·m−2·day−1. This gas channeling is mainly related to soil compaction and climatic perturbation. This has significant implications for design‐adapted detection and monitoring strategies of early leakage in commercial CO2 storage. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd

Atmospheric dispersion modelling of CO2 emission in the Colli Albani volcanic district (Central Italy)

“…According to Norstadt [1984], Xu and Qi [2001] and Gasparini et al [2015], an increase of ambient temperature increases CO 2 soil fluxes intensity. Instead, for this case study, an inverse correlation is found between CO 2 soil flux and temperature (Figures 9 and 10): the plot and the multiple regression model show that both air T and the horizontal component of wind speed are anti-correlated with carbon dioxide air concentration, and is clearly visible how CO 2 concentration increases when temperature and wind speed drop.…”

“…This is a significant uncertainty for the input data implementation in the numerical model. As indicated in Gasparini et al [2015], atmospheric pressure variations over a leakage gas site can move up or delay the emission from soil to atmosphere. Nevertheless, no abrupt change in pressure condition happened during measurements.…”

Modeling CO2 flow in support of a shallow subsurface controlled leakage field test

“…3 m) horizontal well for CO 2 release. Other relevant experiments include the Ginninderra (Australia, 2010), with the longest running injection (up to 80 days); the CO 2 FieldLab in Norway (2011), one of the deepest injection wells (20 m, at 45° inclination) and the highest injection rates; the CO 2 ‐Vadose project in France, where CO 2 was injected in a limestone quarry; and the PISCO 2 in Spain, where CO 2 was injected in artificially constructed tanks filled with soil. Further details and information on these experiments, among others, can be found in comprehensive reviews published recently by Ko et al .…”

“…The ZERT experiment was modeled using the TOUGH2/EOS7CA software to predict the injection rate and design monitoring strategies . The same code was used to simulate different injection scenarios (injection rates, soil characteristics, weather events) within the PISCO 2 project, and also the injection of nitrogen and CO 2 in the Maguelone site in France (as part of the SIMEx project) . The PHREEQC code was used to model changes in water composition with CO 2 injection and dissolution during the field experiment at the CO 2 FieldLab site in Norway .…”

Understanding greenhouse gases: mission being accomplished

“…Field work is being done and mathematical tools are being developed not only to pass stage‐gates for CCS projects, but also to convince policymakers and the general public of the benefits of CO 2 underground storage at a local level. Examples of such work are given in this issue …”