The National Methane Hydrates R&D Program
DOE/NETL Methane Hydrate Projects
|Application of CrunchFlow Routines to Constrain Present and Past Carbon Fluxes at Gas-Hydrate Bearing Sites
||Last Reviewed 12/11/2013
The goal of this project is to apply a multi-component, multi-dimensional reactive transport simulation code to constrain modern day methane fluxes and to reconstruct past episodes of methane flux that can be correlated with environmental changes.
Oregon State University – Corvallis, OR
The importance of understanding the role that gas hydrates play in the global carbon cycle and in understanding their potential as a future energy resource have long been recognized and are key components of the Methane Hydrate R&D Program. Fundamental questions remain, however, as to the residence time of gas hydrates near the seafloor and deeper within the sediment column, the sources and pathways of methane transport, nature and driving mechanisms for flow, and changes in these variables over time.
In order to better understand these fundamental dynamics of methane in present and past environments, Oregon State University will model the complex nature of these interactions by adapting a comprehensive kinetic transport-reaction model based on the CrunchFlow code (Steefel, 2009) to simulate the processes occurring in the sediment column (diagenesis, sediment burial, fluid advection, and multi-component diffusion) and estimate net seafloor fluxes of solutes. CrunchFlow is a software package for modeling and simulation of reactive flow and transport through porous media including groundwater aquifers, soils, sediments, and crystalline rocks. The software can be used to simulate a range of important processes and environments, including reactive contaminant transport, chemical weathering, carbon sequestration, biogeochemical cycling, and water-rock interaction. CrunchFlow is available as a free download at http://www.csteefel.com/DownloadCrunchflow.html [external site] . The user's manual for CrunchFlow is available below under "Additional Information".
Development of a set of user-friendly CrunchFlow-based geochemical modules, tested and implemented using readily available field data (e.g., Cascadia, India, Ulleung Basin), will result in a more complete set of proxies to reconstruct changes in methane flux over time. A coherent set of simulation tools can be used in an integrated approach for future field projects such as those being proposed for the Arctic margin and other high methane flux sites and climate sensitive gas hydrate-bearing regions worldwide.
A complete kinetic model describing the biogeochemical cycling around the sulfate-methane-transition-zone has been formulated. The model accounts for changes in the concentration and isotopic profiles of various dissolved and solid species. A preliminary version of this model was tested with biogeochemical data collected from the K-G basin in India.
The kinetic model was applied to pore water data collected from eight sites drilled during the second Ulleung Basin gas hydrate drilling expedition (UBGH2) in South Korea in 2010. The model revealed very different biogeochemical environments between acoustic chimneys (three of the eight sites) and non-chimney or background sites (the remaining five sites). While anaerobic oxidation of methane predominates both the carbon and sulfur cycles in the chimney environments, organic matter decomposition is an important process for production of methane and dissovled inorganic carbon, and for the consumption of sulfate in the non-chimney sites. These modeling results have been submitted as a draft manuscript to Geochemica et Cosmochimica Acta.
Current Status (December 2013)
A draft manuscript is being prepared which discusses the modeling results associated with the final project task and milestone. This milestone extends the kinetic model to describe the full suite of biogeochemical reactions involved in the precipitation and dissolution of barite. The model was applied to the sedimentary barite record in southern Hydrate Ridge and used to reconstruct the history of the methane, differentiating between methane produced in situ through methanogeneis from methane delivered externally from outside of the model regime.
Project Start: October 1, 2012
Project End: January 31, 2014
Project Cost Information:
DOE Contribution: $88,537
Performer Contribution: $28,831
NETL – Robert Vagnetti (Robert.Vagnetti@netl.doe.gov or 304-285-1334)
Oregon State University – Marta E. Torres (firstname.lastname@example.org or 541-737-2902)
Research Performance Progress Report [PDF-1.15MB] July - September, 2013
Research Performance Progress Report [PDF-370KB] April - June, 2013
Research Performance Progress Report [PDF-143KB] January - March, 2013
CrunchFlow User's Manual [PDF-446KB]