title: Detecting supercritical CO2 in brine at sequestration pressure with an optical fiber sensor.
abstract: Monitoring of sequestered carbon is essential to establishing the environmental safety and the efficacy of geological carbon sequestration. Sequestration in saline aquifers requires the detection of supercritical CO(2) and CO(2)-saturated brine as distinct from the native reservoir brine. Here we demonstrate an all-optical approach to detect both supercritical CO(2), and saturated brine under sequestration conditions. The method employs a long-period grating written on an optical fiber with a resonance wavelength that is sensitive to local refractive index within a pressure- and temperature-controlled apparatus at 40 °C and 1400 psi (9.65 MPa). The supercritical CO(2) and brine are clearly distinguished by a wavelength shift of 1.149 nm (refractive index difference of 0.2371). The CO(2)-saturated brine is also detectable relative to brine, with a resonance wavelength shift of 0.192 nm (refractive index difference of 0.0396). Importantly, these findings indicate the potential for distributed, all-optical monitoring of CO(2) sequestration in saline aquifers.
authors.affiliation: Department of Mechanical and Industrial Engineering, Center for Sustainable Energy, University of Toronto, 5 King’s College Road, Toronto, Ontario M5S 3G8, Canada.
authors.forename: Bo
authors.initials: B
authors.lastname: Bao
authors.forename: Luis
authors.initials: L
authors.lastname: Melo
authors.forename: Benjamin
authors.initials: B
authors.lastname: Davies
authors.forename: Hossein
authors.initials: H
authors.lastname: Fadaei
authors.forename: David
authors.initials: D
authors.lastname: Sinton
authors.forename: Peter
authors.initials: P
authors.lastname: Wild
mesh_terms: D002245:Carbon Dioxide / Q000032:analysis*; D057965:Carbon Sequestration; D004784:Environmental Monitoring; D004867:Equipment Design; D055100:Optical Fibers; D011312:Pressure; D012492:Salts / Q000032:analysis*
chemical_list: D012492:Salts; C017082:brine; D002245:Carbon Dioxide