title: Injection of CO2-saturated water through a siliceous sandstone plug from the Hontomin test site (Spain): experiment and modeling.
abstract: Massive chemical reactions are not expected when injecting CO(2) in siliceous sandstone reservoirs, but their performance can be challenged by small-scale reactions and other processes affecting their transport properties. We have conducted a core flooding test with a quartzarenite plug of Lower Cretaceous age representative of the secondary reservoir of the Hontomín test site. The sample, confined at high pressure, was successively injected with DIW and CO(2)-saturated DIW for 49 days while monitoring geophysical, chemical, and hydrodynamic parameters. The plug experienced little change, without evidence of secondary carbonation. However, permeability increased by a factor of 4 (0.022-0.085 mD), and the V(P)/V(S) ratio, whose change is related with microcracking, rose from ~1.68 to ~1.8. Porosity also increased (7.33-8.1%) from the beginning to the end of the experiment. Fluid/rock reactions were modeled with PHREEQC-2, and they are dominated by the dissolution of Mg-calcite. Mass balances show that ~4% of the initial carbonate was consumed. The results suggest that mineral dissolution and microcracking may have acted in a synergistic way at the beginning of the acidic flooding. However, dissolution processes concentrated in pore throats can better explain the permeability enhancement observed over longer periods of time.
authors: Fundación Ciudad de la Energía, Avenida Compostilla II no 2, 24404 Ponferrada, Spain.
authors: J
authors: J
authors: Canal
authors: J
authors: J
authors: Delgado
authors: I
authors: I
authors: Falcón
authors: Q
authors: Q
authors: Yang
authors: R
authors: R
authors: Juncosa
authors: V
authors: V
authors: Barrientos
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D057965:Carbon Sequestration; D008903:Minerals / Q000737:chemistry*; D008962:Models, Theoretical; D013030:Spain; D014867:Water / Q000737:chemistry
chemical_list: D008903:Minerals; D014867:Water; D002245:Carbon Dioxide