CO2/Brine Transport into Shallow Aquifers along Fault Zones

详细信息    查看全文

• 作者：Elizabeth H. Keating ; Dennis L. Newell ; Hari Viswanathan ; J. W. Carey ; G. Zyvoloski ; Rajesh Pawar
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：January 2, 2013
• 年：2013
• 卷：47
• 期：1
• 页码：290-297
• 全文大小：580K
• 年卷期：v.47,no.1(January 2, 2013)
• ISSN：1520-5851

文摘

Unintended release of CO₂ from carbon sequestration reservoirs poses a well-recognized risk to groundwater quality. Research has largely focused on in situ CO₂-induced pH depression and subsequent trace metal mobilization. In this paper we focus on a second mechanism: upward intrusion of displaced brine or brackish-water into a shallow aquifer as a result of CO₂ injection. Studies of two natural analog sites provide insights into physical and chemical mechanisms controlling both brackish water and CO₂ intrusion into shallow aquifers along fault zones. At the Chimay贸, New Mexico site, shallow groundwater near the fault is enriched in CO₂ and, in some places, salinity is significantly elevated. In contrast, at the Springerville, Arizona site CO₂ is leaking upward through brine aquifers but does not appear to be increasing salinity in the shallow aquifer. Using multiphase transport simulations we show conditions under which significant CO₂ can be transported through deep brine aquifers into shallow layers. Only a subset of these conditions favor entrainment of salinity into the shallow aquifer: high aspect-ratio leakage pathways and viscous coupling between the fluid phases. Recognition of the conditions under which salinity is favored to be cotransported with CO₂ into shallow aquifers will be important in environmental risk assessments.