Numerical studies of CO₂ and brine leakage into a shallow aquifer through an open wellbore

Journal Article · Thu Nov 09 00:00:00 EST 2017 · Hydrogeology Journal

DOI:https://doi.org/10.1007/s10040-017-1685-y· OSTI ID:1476630

Wang, Jingrui ^[1]; Hu, Litang ^[1]; Pan, Lehua ^[2]; Zhang, Keni ^[2]

---

1. Beijing Normal Univ., Beijing (China). College of Water Sciences, Engineering Research Center of Groundwater Pollution Control and Remediation of Ministry of Education
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Geosciences Division

Industrial-scale geological storage of CO₂ in saline aquifers may cause CO₂ and brine leakage from abandoned wells into shallow fresh aquifers. This leakage problem involves the flow dynamics in both the wellbore and the storage reservoir. T2Well/ECO2N, a coupled wellbore-reservoir flow simulator, was used to analyze CO₂ and brine leakage under different conditions with a hypothetical simulation model in water-CO₂-brine systems. Parametric studies on CO₂ and brine leakage, including the salinity, excess pore pressure (EPP) and initially dissolved CO₂ mass fraction, are conducted to understand the mechanism of CO₂ migration. The results show that brine leakage rates increase proportionally with EPP and inversely with the salinity when EPP varies from 0.5 to 1.5 MPa; however, there is no CO₂ leakage into the shallow freshwater aquifer if EPP is less than 0.5 MPa. The dissolved CO₂ mass fraction shows an important influence on the CO₂ plume, as part of the dissolved CO₂ becomes a free phase. Scenario simulation shows that the gas lifting effect will significantly increase the brine leakage rate into the shallow freshwater aquifer under the scenario of 3.89% dissolved CO₂ mass fraction. The equivalent porous media (EPM) approach used to model the wellbore flow has been evaluated and results show that the EPM approach could either under- or over-estimate brine leakage rates under most scenarios. The discrepancies become more significant if a free CO₂ phase evolves. Therefore, a model that can correctly describe the complex flow dynamics in the wellbore is necessary for investigating the leakage problems.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1476630
• Journal Information: Hydrogeology Journal, Vol. 26, Issue 2; ISSN 1431-2174
• Publisher: Springer
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES