Testing carbon sequestration site monitor instruments using a controlled carbon dioxide release facility.

Abstract

Two laser-based instruments for carbon sequestration site monitoring have been developed and tested at a controlled carbon dioxide $\left({\text{CO}}_{\text{2}}\right)$ release facility. The first instrument uses a temperature tunable distributed feedback (DFB) diode laser capable of accessing the $2.0027–2.0042\mu \text{m}$ spectral region that contains three ${\text{CO}}_{\text{2}}$ absorption lines and is used for aboveground atmospheric ${\text{CO}}_{\text{2}}$ concentration measurements. The second instrument also uses a temperature tunable DFB diode laser capable of accessing the $2.0032–2.0055\mu \text{m}$ spectral region that contains five ${\text{CO}}_{\text{2}}$ absorption lines for underground ${\text{CO}}_{\text{2}}$ soil gas concentration measurements. The performance of these instruments for carbon sequestration site monitoring was studied using a newly developed controlled ${\text{CO}}_{\text{2}}$ release facility. A 0.3 ton ${\text{CO}}_{\text{2}}/\text{day}$ injection experiment was performed from 3–10 August 2007. The aboveground differential absorption instrument measured an average atmospheric ${\text{CO}}_{\text{2}}$ concentration of 618 parts per million (ppm) over the ${\text{CO}}_{\text{2}}$ injection site compared with an average background atmospheric ${\text{CO}}_{\text{2}}$ concentration of $448\text{\hspace{0.17em} ppm}$ demonstrating this instrument's capability for carbon sequestration site monitoring. The underground differential absorption instrument measured a ${\text{CO}}_{\text{2}}$ soil gas concentration of 100,000 ppm during the ${\text{CO}}_{\text{2}}$ injection, a factor of 25 greater than the measured background ${\text{CO}}_{\text{2}}$ soil gas concentration of 4000 ppm demonstrating this instrument's capability for carbon sequestration site monitoring