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Title: Merits of pressure and geochemical data as indicators of CO 2 /brine leakage into a heterogeneous, sedimentary aquifer

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Publication Date:
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
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Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
International Journal of Greenhouse Gas Control
Additional Journal Information:
Journal Volume: 52; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 09:56:04; Journal ID: ISSN 1750-5836
Country of Publication:

Citation Formats

Trainor-Guitton, Whitney, Mansoor, Kayyum, Sun, Yunwei, and Carroll, Susan. Merits of pressure and geochemical data as indicators of CO 2 /brine leakage into a heterogeneous, sedimentary aquifer. Netherlands: N. p., 2016. Web. doi:10.1016/j.ijggc.2016.07.002.
Trainor-Guitton, Whitney, Mansoor, Kayyum, Sun, Yunwei, & Carroll, Susan. Merits of pressure and geochemical data as indicators of CO 2 /brine leakage into a heterogeneous, sedimentary aquifer. Netherlands. doi:10.1016/j.ijggc.2016.07.002.
Trainor-Guitton, Whitney, Mansoor, Kayyum, Sun, Yunwei, and Carroll, Susan. 2016. "Merits of pressure and geochemical data as indicators of CO 2 /brine leakage into a heterogeneous, sedimentary aquifer". Netherlands. doi:10.1016/j.ijggc.2016.07.002.
title = {Merits of pressure and geochemical data as indicators of CO 2 /brine leakage into a heterogeneous, sedimentary aquifer},
author = {Trainor-Guitton, Whitney and Mansoor, Kayyum and Sun, Yunwei and Carroll, Susan},
abstractNote = {},
doi = {10.1016/j.ijggc.2016.07.002},
journal = {International Journal of Greenhouse Gas Control},
number = C,
volume = 52,
place = {Netherlands},
year = 2016,
month = 9

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.ijggc.2016.07.002

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  • An important risk at CO2 storage sites is the potential for groundwater quality impacts. As part of a system to assess the potential for these impacts a geochemical scaling function has been developed, based on a detailed reactive transport model of CO2 and brine leakage into an unconfined, oxidizing carbonate aquifer. Stochastic simulations varying a number of geochemical parameters were used to generate a response surface predicting the volume of aquifer that would be impacted with respect to regulated contaminants. The brine was assumed to contain several trace metals and organic contaminants. Aquifer pH and TDS were influenced by CO2more » leakage, while trace metal concentrations were most influenced by the brine concentrations rather than adsorption or desorption on calcite. Organic plume sizes were found to be strongly influenced by biodegradation.« less
  • Investigations of underpressure aquifers can be improved by accounting for factors that impede accurate interpretation of pressure-depth plots. Poor data quality and distribution obscure true pressure-depth trends. Plotted data may also be distorted by the hydrogeologic setting, i.e., the surface topography, the structural dip of the aquifer, and the potentiometric surface. In the Palo Duro Basin in the Texas Panhandle, distortions caused by the hydrogeologic setting are reduced by delineating regions having little variations in surface topography and in structural dip of the aquifer. Pressure-depth plots for these regions vary considerably. The effects of the hydrogeologic setting on these plotsmore » were evaluated by computing pressure-depth data for flow parallel to the structural dip of the aquifer in each region. By comparing regression lines through real pressure-depth data with those through computed data, true hydrologic conditions could be distinguished from the misleading effects of the hydrogeologic setting on pressure-depth plots.« less
  • The National Risk Assessment Partnership (NRAP) consists of 5 U.S DOE national laboratories collaborating to develop a framework for predicting the risks associated with carbon sequestration. The approach taken by NRAP is to divide the system into components, including injection target reservoirs, wellbores, natural pathways including faults and fractures, groundwater and the atmosphere. Next, develop a detailed, physics and chemistry-based model of each component. Using the results of the detailed models, develop efficient, simplified models, termed reduced order models (ROM) for each component. Finally, integrate the component ROMs into a system model that calculates risk profiles for the site. Thismore » report details the development of the Groundwater Geochemistry ROM for the Edwards Aquifer at PNNL. The Groundwater Geochemistry ROM for the Edwards Aquifer uses a Wellbore Leakage ROM developed at LANL as input. The detailed model, using the STOMP simulator, covers a 5x8 km area of the Edwards Aquifer near San Antonio, Texas. The model includes heterogeneous hydraulic properties, and equilibrium, kinetic and sorption reactions between groundwater, leaked CO2 gas, brine, and the aquifer carbonate and clay minerals. Latin Hypercube sampling was used to generate 1024 samples of input parameters. For each of these input samples, the STOMP simulator was used to predict the flux of CO2 to the atmosphere, and the volume, length and width of the aquifer where pH was less than the MCL standard, and TDS, arsenic, cadmium and lead exceeded MCL standards. In order to decouple the Wellbore Leakage ROM from the Groundwater Geochemistry ROM, the response surface was transformed to replace Wellbore Leakage ROM input parameters with instantaneous and cumulative CO2 and brine leakage rates. The most sensitive parameters proved to be the CO2 and brine leakage rates from the well, with equilibrium coefficients for calcite and dolomite, as well as the number of illite and kaolinite sorption sites proving to be of secondary importance. The Groundwater Geochemistry ROM was developed using nonlinear regression to fit the response surface with a quadratic polynomial. The goodness of fit was excellent for the CO2 flux to the atmosphere, and very good for predicting the volumes of groundwater exceeding the pH, TDS, As, Cd and Pb threshold values.« less
  • Predicting and quantifying impacts of potential carbon dioxide (CO2) leakage into shallow aquifers that overlie geologic CO2 storage formations is an important part of developing reliable carbon storage techniques. Leakage of CO2 through fractures, faults or faulty wellbores can reduce groundwater pH, inducing geochemical reactions that release solutes into the groundwater and pose a risk of degrading groundwater quality. In order to help quantify this risk, predictions of metal concentrations are needed during geologic storage of CO2. Here, we present regional-scale reactive transport simulations, at relatively fine-scale, of CO2 leakage into shallow aquifers run on the PFLOTRAN platform using high-performancemore » computing. Multiple realizations of heterogeneous permeability distributions were generated using standard geostatistical methods. Increased statistical anisotropy of the permeability field resulted in more lateral and vertical spreading of the plume of impacted water, leading to increased Pb2+ (lead) concentrations and lower pH at a well down gradient of the CO2 leak. Pb2+ concentrations were higher in simulations where calcite was the source of Pb2+ compared to galena. The low solubility of galena effectively buffered the Pb2+ concentrations as galena reached saturation under reducing conditions along the flow path. In all cases, Pb2+ concentrations remained below the maximum contaminant level set by the EPA. Results from this study, compared to natural variability observed in aquifers, suggest that bicarbonate (HCO3) concentrations may be a better geochemical indicator of a CO2 leak under the conditions simulated here.« less