Laser-Induced Breakdown Spectroscopy (LIBS) of a High-Pressure CO₂–Water Mixture: Application to Carbon Sequestration

Abstract

Geologic carbon storage in deep saline aquifers is considered a feasible and possible approach of mitigating the problem of increasing greenhouse gas emissions. However, there are latent risks in which carbon dioxide (CO2) could migrate from the deep saline formations to shallower aquifers. In the event of a significant CO2 leakage to an underground source of drinking water, CO2 will dissolve in the water, thereby increasing its acidity, which could potentially enhance the solubility of various aquifer constituents, including hazardous compounds, subsequently compromising groundwater quality due to increased concentration of aqueous metals. In this paper we explore the possibility of detecting such leakage by the use of laser-induced breakdown spectroscopy (LIBS). The experiments were conducted in calcium chloride solution at three pressures of 10, 50, and 120 bar. To evaluate the direct effect of elevated CO2 on the intensity of calcium emission lines (422.67 and 393.37 nm), we also performed experiments with pure nitrogen (N2) gas, offering large water solubility contrast. We found that when performed in presence of CO2, LIBS showed only a modest decrease in Ca emission intensity from 10 to 120 bar compared to N2. These results indicate that LIBS is a viable tool for measuring brine/water contents in high-pressure CO2 environment and can be applied for monitoring CO2 leakage and displaced brine migration.

A critical review of recent progress in analytical laser-induced breakdown spectroscopy

“…It was found that DP-LIBS emission is inversely proportional to the pressure of the liquid, and the maximum emission can be obtained when the interpulse delay is set in such a way that the second laser pulse hits the vapor bubble generated by the first pulse when it has the largest diameter. Recent carbonsequestration studies assess the possibility of using LIBS for monitoring purposes in deep saline aquifers, which requires measurements in a high-pressure water-CO 2 mixture [219,220]. It was found that elemental emissions in the liquid were not significantly affected by the presence of dissolved of CO 2 , and thus LIBS was regarded as a viable tool for this monitoring task.…”

Development of a subsurface LIBS sensor for in situ groundwater quality monitoring with applications in CO2 leak sensing in carbon sequestration

“…Previous work in our and other laboratories has shown that underwater LIBS can successfully be used for the elemental analysis of aqueous solutions with and without a saline sample matrix. These studies focus on measurements at high pressure 4,14–20 , as well as at atmospheric pressure 21–27 conditions. The underwater LIBS technique relies on focusing a high peak power pulsed laser into a liquid sample to generate a plasma.…”

Laser Spectroscopic Sensors for the Development of Anthropomorphic Robot Sensitivity

“…A LIBS device (ChemiCam module) was installed in a ROV and deep sea in situ tests were done to obtain the chemical composition of seawater and perform a geochemical test of mineral deposits for the first time [ 12 ]. The improvement of this method is an ongoing topic of research [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. One way to improve this method is to use double pulse and multi pulse laser breakdowns [ 22 , 23 , 24 ].…”