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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>David R. Cole</dc:contributor>
  <dc:contributor>Susan D. Hovorka</dc:contributor>
  <dc:contributor>W.D. Gunter</dc:contributor>
  <dc:contributor>Kevin G. Knauss</dc:contributor>
  <dc:contributor>Barry M. Freifeild</dc:contributor>
  <dc:creator>Yousif K. Kharaka</dc:creator>
  <dc:date>2006</dc:date>
  <dc:description>&lt;p class="p1"&gt;&lt;span class="s1"&gt;To investigate the potential for the geologic storage of CO&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt; in saline sedimentary aquifers, 1600 t of CO&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt; were injected at 1500 m depth into a 24-m-thick sandstone section of the Frio Formation, a regional brine and oil reservoir in the U.S. Gulf Coast. Fluid samples obtained from the injection and observation wells before CO&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt; injection showed a Na-Ca-Cl–type brine with 93,000 mg/L total dissolved solids (TDS) at near saturation with CH&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt; at reservoir conditions. Following CO&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt; breakthrough, samples showed sharp drops in pH (6.5–5.7), pronounced increases in alkalinity (100–3000 mg/L as HCO&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt;) and Fe (30–1100 mg/L), and significant shifts in the isotopic compositions of H&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt;O, dissolved inorganic carbon (DIC), and CH&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt;. Geochemical modeling indicates that brine pH would have dropped lower but for the buffering by dissolution of carbonate and iron oxyhydroxides. This rapid dissolution of carbonate and other minerals could ultimately create pathways in the rock seals or well cements for CO&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt; and brine leakage. Dissolution of minerals, especially iron oxyhydroxides, could mobilize toxic trace metals and, where residual oil or suitable organics are present, the injected CO&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt; could also mobilize toxic organic compounds. Environmental impacts could be major if large brine volumes with mobilized toxic metals and organics migrated into potable groundwater. The δ&lt;/span&gt;&lt;span class="s2"&gt;&lt;sup&gt;18&lt;/sup&gt;&lt;/span&gt;&lt;span class="s1"&gt;O values for brine and CO&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt; samples indicate that supercritical CO&lt;/span&gt;&lt;span class="s2"&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class="s1"&gt; comprises ∼50% of pore-fluid volume ∼6 mo after the end of injection. Postinjection sampling, coupled with geochemical modeling, indicates that the brine gradually will return to its preinjection composition.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1130/G22357.1</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>The Geological Society of America</dc:publisher>
  <dc:title>Gas-water-rock interactions in Frio Formation following CO&lt;sub&gt;2&lt;/sub&gt; injection: Implications for the storage of greenhouse gases in sedimentary basins</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>