Rapid surface detection of CO2 leaks from geologic sequestration sites

AbstractThis study focuses on developing a method to characterize and detect leakage of carbon dioxide from a geologic sequestration site using a Picarro gas analyser, and to systematically evaluate the robustness of detection ability and optimize the data acquisition parameters by testing under varying conditions at the Zero Emissions Research and Technology field site in Bozeman, MT. It was determined (1) both 12CO2 or 13CO2 measurements provide equally good leak detection ability, (2) wind speed and direction does not limit detection ability with a sampling height less than 30cm, and (3) δ13C measurements did not provide a reliable method for leak detection with our data acquisition strategy

Final Report for the ZERT Project: Basic Science of Retention Issues, Risk Assessment & Measurement, Monitoring and Verification for Geologic Sequestration

ZERT has made major contributions to five main areas of sequestration science: improvement of computational tools; measurement and monitoring techniques to verify storage and track migration of CO{sub 2}; development of a comprehensive performance and risk assessment framework; fundamental geophysical, geochemical and hydrological investigations of CO{sub 2} storage; and investigate innovative, bio-based mitigation strategies

Looking for leakage or monitoring for public assurance?

Monitoring is a regulatory requirement for all carbon dioxide capture and geological storage (CCS) projects to verify containment of injected carbon dioxide (CO2) within a licensed geological storage complex. Carbon markets require CO2 storage to be verified. The public wants assurances CCS projects will not cause any harm to themselves, the environment or other natural resources. In the unlikely event that CO2 leaks from a storage complex, and into groundwater, to the surface, atmosphere or ocean, then monitoring methods will be required to locate, assess and quantify the leak, and to inform the community about the risks and impacts on health, safety and the environment. This paper considers strategies to improve the efficiency of monitoring the large surface area overlying onshore storage complexes. We provide a synthesis of findings from monitoring for CO2 leakage at geological storage sites both natural and engineered, and from monitoring controlled releases of CO2 at four shallow release facilities – ZERT (USA), Ginninderra (Australia), Ressacada (Brazil) and CO2 field lab (Norway)

Potential for a Process-based Monitoring Method above Geologic Carbon Storage Sites using Dissolved Gases in Freshwater Aquifers

AbstractThe process-based method is a new technique for monitoring CO2 storage permanence in the vadose zone above geologic carbon storage (GCS) sites. This method uses ratios of coexisting gas species to understand geochemical processes rather than comparing CO2concentrations with large baseline data sets, thereby making monitoring more efficient. In the vadose zone, ratios among coexisting gases (CO2, O2, N2 and CH4) have been used to distinguish biologic respiration, water-rock-CO2 interaction, and methane oxidation from a leakage signal. We report the preliminary results of a feasibility test conducted in July 2012 at the Zero Emission Research and Technology Center (ZERT) controlled release site in Montana, USA to discern whether the method could be applied to dissolved gases in groundwater, thereby enhancing groundwater monitoring. Preliminary results are favorable, making the process- based approach potentially useful for monitoring shallow freshwater aquifers above GCS sites

Modeling Gas Transport in the Shallow Subsurface During the ZERT CO2 Release Test

We used the multiphase and multicomponent TOUGH2/EOS7CA model to carry out predictive simulations of CO{sub 2} injection into the shallow subsurface of an agricultural field in Bozeman, Montana. The purpose of the simulations was to inform the choice of CO{sub 2} injection rate and design of monitoring and detection activities for a CO{sub 2} release experiment. The release experiment configuration consists of a long horizontal well (70 m) installed at a depth of approximately 2.5 m into which CO{sub 2} is injected to mimic leakage from a geologic carbon sequestration site through a linear feature such as a fault. We estimated the permeability of the soil and cobble layers present at the site by manual inversion of measurements of soil CO{sub 2} flux from a vertical-well CO{sub 2} release. Based on these estimated permeability values, predictive simulations for the horizontal well showed that CO{sub 2} injection just below the water table creates an effective gas-flow pathway through the saturated zone up to the unsaturated zone. Once in the unsaturated zone, CO{sub 2} spreads out laterally within the cobble layer, where liquid saturation is relatively low. CO{sub 2} also migrates upward into the soil layer through the capillary barrier and seeps out at the ground surface. The simulations predicted a breakthrough time of approximately two days for the 100kg d{sup -1} injection rate, which also produced a flux within the range desired for testing detection and monitoring approaches. The seepage area produced by the model was approximately five meters wide above the horizontal well, compatible with the detection and monitoring methods tested. For a given flow rate, gas-phase diffusion of CO{sub 2} tends to dominate over advection near the ground surface, where the CO{sub 2} concentration gradient is large, while advection dominates deeper in the system