skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Up-Scaling Geochemical Reaction Rates for Carbon Dioxide (CO2) in Deep Saline Aquifers

Abstract

Geochemical reactions in deep subsurface environments are complicated by the consolidated nature and mineralogical complexity of sedimentary rocks. Understanding the kinetics of these reactions is critical to our ability to make long-term predictions about subsurface processes such as pH buffering, alteration in rock structure, permeability changes, and formation of secondary precipitates. In this project, we used a combination of experiments and numerical simulation to bridge the gap between our knowledge of these reactions at the lab scale and rates that are meaningful for modeling reactive transport at core scales. The focus is on acid-driven mineral dissolution, which is specifically relevant in the context of CO2-water-rock interactions in geological sequestration of carbon dioxide. The project led to major findings in three areas. First, we modeled reactive transport in pore-network systems to investigate scaling effects in geochemical reaction rates. We found significant scaling effects when CO2 concentrations are high and reaction rates are fast. These findings indicate that the increased acidity associated with geological sequestration can generate conditions for which proper scaling tools are yet to be developed. Second, we used mathematical modeling to investigate the extent to which SO2, if co-injected with CO2, would acidify formation brines. We found that theremore » exist realistic conditions in which the impact on brine acidity will be limited due to diffusion rate-limited SO2 dissolution from the CO2 phase, and the subsequent pH shift may also be limited by the lack of availability of oxidants to produce sulfuric acid. Third, for three Viking sandstones (Alberta sedimentary basin, Canada), we employed backscattered electron microscopy and energy dispersive X-ray spectroscopy to statistically characterize mineral contact with pore space. We determined that for reactive minerals in sedimentary consolidated rocks, abundance alone is not a good predictor of mineral accessible surface area, and should not be used in reactive transport modeling. Our work showed that reaction rates would be overestimated by three to five times.« less

Authors:
Publication Date:
Research Org.:
Princeton Univ., NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1064444
Report Number(s):
DOE/DE-FG02-05ER15636-01
DOE Contract Number:
FG02-05ER15636
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; reactive transport, upscaling, geochemical reactions, water-rock-interactions, reactive surface area

Citation Formats

Peters, Catherine A. Up-Scaling Geochemical Reaction Rates for Carbon Dioxide (CO2) in Deep Saline Aquifers. United States: N. p., 2013. Web. doi:10.2172/1064444.
Copy to clipboard
Peters, Catherine A. Up-Scaling Geochemical Reaction Rates for Carbon Dioxide (CO2) in Deep Saline Aquifers. United States. doi:10.2172/1064444.
Copy to clipboard
Peters, Catherine A. Thu . "Up-Scaling Geochemical Reaction Rates for Carbon Dioxide (CO2) in Deep Saline Aquifers". United States. doi:10.2172/1064444. https://www.osti.gov/servlets/purl/1064444.
Copy to clipboard
@article{osti_1064444,
title = {Up-Scaling Geochemical Reaction Rates for Carbon Dioxide (CO2) in Deep Saline Aquifers},
author = {Peters, Catherine A},
abstractNote = {Geochemical reactions in deep subsurface environments are complicated by the consolidated nature and mineralogical complexity of sedimentary rocks. Understanding the kinetics of these reactions is critical to our ability to make long-term predictions about subsurface processes such as pH buffering, alteration in rock structure, permeability changes, and formation of secondary precipitates. In this project, we used a combination of experiments and numerical simulation to bridge the gap between our knowledge of these reactions at the lab scale and rates that are meaningful for modeling reactive transport at core scales. The focus is on acid-driven mineral dissolution, which is specifically relevant in the context of CO2-water-rock interactions in geological sequestration of carbon dioxide. The project led to major findings in three areas. First, we modeled reactive transport in pore-network systems to investigate scaling effects in geochemical reaction rates. We found significant scaling effects when CO2 concentrations are high and reaction rates are fast. These findings indicate that the increased acidity associated with geological sequestration can generate conditions for which proper scaling tools are yet to be developed. Second, we used mathematical modeling to investigate the extent to which SO2, if co-injected with CO2, would acidify formation brines. We found that there exist realistic conditions in which the impact on brine acidity will be limited due to diffusion rate-limited SO2 dissolution from the CO2 phase, and the subsequent pH shift may also be limited by the lack of availability of oxidants to produce sulfuric acid. Third, for three Viking sandstones (Alberta sedimentary basin, Canada), we employed backscattered electron microscopy and energy dispersive X-ray spectroscopy to statistically characterize mineral contact with pore space. We determined that for reactive minerals in sedimentary consolidated rocks, abundance alone is not a good predictor of mineral accessible surface area, and should not be used in reactive transport modeling. Our work showed that reaction rates would be overestimated by three to five times.},
doi = {10.2172/1064444},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Feb 28 00:00:00 EST 2013},
month = {Thu Feb 28 00:00:00 EST 2013}
}
Copy to clipboard
Technical Report:
View Technical Report (2.11 MB)
DOI:  10.2172/1064444
Save / Share:
Export Metadata
Save to My Library
You must Sign In or Create an Account in order to save documents to your library.

  • The overall goal of the project was to bridge the gap between our knowledge of small-scale geochemical reaction rates and reaction rates meaningful for modeling transport at core scales. The working hypothesis was that reaction rates, determined from laboratory measurements based upon reactions typically conducted in well mixed batch reactors using pulverized reactive media may be significantly changed in in situ porous media flow due to rock microstructure heterogeneity. Specifically we hypothesized that, generally, reactive mineral surfaces are not uniformly accessible to reactive fluids due to the random deposition of mineral grains and to the variation in flow rates withinmore » a pore network. Expected bulk reaction rates would therefore have to be correctly up-scaled to reflect such heterogeneity. The specific objective was to develop a computational tool that integrates existing measurement capabilities with pore-scale network models of fluid flow and reactive transport. The existing measurement capabilities to be integrated consisted of (a) pore space morphology, (b) rock mineralogy, and (c) geochemical reaction rates. The objective was accomplished by: (1) characterizing sedimentary sandstone rock morphology using X-ray computed microtomography, (2) mapping rock mineralogy using back-scattered electron microscopy (BSE), X-ray dispersive spectroscopy (EDX) and CMT, (3) characterizing pore-accessible reactive mineral surface area, and (4) creating network models to model acidic CO{sub 2} saturated brine injection into the sandstone rock samples.« less

  • ; ;
    A reactive fluid flow and geochemical transport numerical model for evaluating long-term CO{sub 2} disposal in deep aquifers has been developed. Using this model, we performed a number of sensitivity simulations under CO{sub 2} injection conditions for a commonly encountered Gulf Coast sediment to analyze the impact of CO{sub 2} immobilization through carbonate precipitation. Geochemical models are needed because alteration of the predominant host rock aluminosilicate minerals is very slow and is not amenable to laboratory experiment under ambient deep-aquifer conditions. Under conditions considered in our simulations, CO{sub 2} trapping by secondary carbonate minerals such as calcite (CaCO{sub 3}), dolomitemore » (CaMg(CO{sub 3}){sub 2}), siderite (FeCO{sub 3}), and dawsonite (NaAlCO{sub 3}(OH){sub 2}) could occur in the presence of high pressure CO{sub 2}. Variations in precipitation of secondary carbonate minerals strongly depend on rock mineral composition and their kinetic reaction rates. Using the data presented in this paper, CO{sub 2} mineral-trapping capability after 10,000 years is comparable to CO{sub 2} dissolution in pore waters (2-5 kg CO{sub 2} per cubic meter of formation). Under favorable conditions such as increase of the Mg-bearing mineral clinochlore (Mg{sub 5}Al{sub 2}Si{sub 3}O{sub 10}(OH){sub 8}) abundance, the capacity can be larger (10 kg CO{sub 2} per cubic meter of formation) due to increase of dolomite precipitation. Carbon dioxide-induced rock mineral alteration and the addition of CO{sub 2} mass as secondary carbonates to the solid matrix results in decreases in porosity. A maximum 3% porosity decrease is obtained in our simulations. A small decrease in porosity may result in a significant decrease in permeability. The numerical simulations described here provide useful insight into sequestration mechanisms, and their controlling conditions and parameters.« less

  • ; ; ; ...
    Underground carbon storage may become one of the solutions to address global warming. However, to have an impact, carbon storage must be done at a much larger scale than current CO{sub 2} injection operations for enhanced oil recovery. It must also include injection into saline aquifers. An important characteristic of CO{sub 2} is its strong buoyancy--storage must be guaranteed to be sufficiently permanent to satisfy the very reason that CO{sub 2} is injected. This long-term aspect (hundreds to thousands of years) is not currently captured in legislation, even if the U.S. has a relatively well-developed regulatory framework to handle carbonmore » storage, especially in the operational short term. This report proposes a hierarchical approach to permitting in which the State/Federal Government is responsible for developing regional assessments, ranking potential sites (''General Permit'') and lessening the applicant's burden if the general area of the chosen site has been ranked more favorably. The general permit would involve determining in the regional sense structural (closed structures), stratigraphic (heterogeneity), and petrophysical (flow parameters such as residual saturation) controls on the long-term fate of geologically sequestered CO{sub 2}. The state-sponsored regional studies and the subsequent local study performed by the applicant will address the long-term risk of the particular site. It is felt that a performance-based approach rather than a prescriptive approach is the most appropriate framework in which to address public concerns. However, operational issues for each well (equivalent to the current underground injection control-UIC-program) could follow regulations currently in place. Area ranking will include an understanding of trapping modes. Capillary (due to residual saturation) and structural (due to local geological configuration) trappings are two of the four mechanisms (the other two are solubility and mineral trappings), which are the most relevant to the time scale of interest. The most likely pathways for leakage, if any, are wells and faults. We favor a defense-in-depth approach, in which storage permanence does not rely upon a primary seal only but assumes that any leak can be contained by geologic processes before impacting mineral resources, fresh ground water, or ground surface. We examined the Texas Gulf Coast as an example of an attractive target for carbon storage. Stacked sand-shale layers provide large potential storage volumes and defense-in-depth leakage protection. In the Texas Gulf Coast, the best way to achieve this goal is to establish the primary injection level below the total depth of most wells (>2,400 m-8,000 ft). In addition, most faults, particularly growth faults, present at the primary injection level do not reach the surface. A potential methodology, which includes an integrated approach comprising the whole chain of potential events from leakage from the primary site to atmospheric impacts, is also presented. It could be followed by the State/Federal Government, as well as by the operators.« less

  • ;
    As carbon dioxide (CO{sub 2}) is sequestered from the bottom of a brine reservoir and allowed to migrate upward, the effects of the relative permeability hysteresis due to capillary trapping and buoyancy driven migration tend to make the reservoir patchy saturated with different fluid phases over time. Seismically, such a patchy saturated reservoir induces an effective anisotropic behavior whose properties are primarily dictated by the nature of the saturation of different fluid phases in the pores and the elastic properties of the rock matrix. By combining reservoir flow simulation and modeling with seismic modeling, it is possible to derive thesemore » effective anisotropic properties, which, in turn, could be related to the saturation of CO{sub 2} within the reservoir volume any time during the post-injection scenario. Therefore, if time-lapse seismic data are available and could be inverted for the effective anisotropic properties of the reservoir, they, in combination with reservoir simulation could potentially predict the CO{sub 2} saturation directly from the time-lapse seismic data. It is therefore concluded that the time-lapse seismic data could be used to monitor the carbon sequestrated saline reservoirs. But for its successful implementation, seismic modeling and inversion methods must be integrated with the reservoir simulations. In addition, because CO{sub 2} sequestration induces an effective anisotropy in the sequestered reservoir and anisotropy is best detected using multicomponent seismic data compared to single component (P-wave) data, acquisition, processing, and analysis is multicomponent seismic data is recommended for these time-lapse studies. Finally, a successful implementation of using time-lapse seismic data for monitoring the carbon sequestrated saline reservoirs will require development of a robust methodology for inverting multicomponent seismic data for subsurface anisotropic properties.« less

  • Recent research and applications have demonstrated technologically feasible methods, defined costs, and modeled processes needed to sequester carbon dioxide (CO{sub 2}) in saline-water-bearing formations (aquifers). One of the simplifying assumptions used in previous modeling efforts is the effect of real stratigraphic complexity on transport and trapping in saline aquifers. In this study we have developed and applied criteria for characterizing saline aquifers for very long-term sequestration of CO{sub 2}. The purpose of this pilot study is to demonstrate a methodology for optimizing matches between CO{sub 2} sources and nearby saline formations that can be used for sequestration. This project identifiedmore » 14 geologic properties used to prospect for optimal locations for CO{sub 2} sequestration in saline-water-bearing formations. For this demonstration, we digitized maps showing properties of saline formations and used analytical tools in a geographic information system (GIS) to extract areas that meet variably specified prototype criteria for CO{sub 2} sequestration sites. Through geologic models, realistic aquifer properties such as discontinuous sand-body geometry are determined and can be used to add realistic hydrologic properties to future simulations. This approach facilitates refining the search for a best-fit saline host formation as our understanding of the most effective ways to implement sequestration proceeds. Formations where there has been significant drilling for oil and gas resources as well as extensive characterization of formations for deep-well injection and waste disposal sites can be described in detail. Information to describe formation properties can be inferred from poorly known saline formations using geologic models in a play approach. Resulting data sets are less detailed than in well-described examples but serve as an effective screening tool to identify prospects for more detailed work.« less