HYFLUX - Part I: Regional modeling of methane flux from near-seafloor gas hydrate deposits on continental margins

Authors: MacDonald, I.R., Asper, V., Garcia, O., Kastner, M., Leifer, I., Naehr, T.H., Solomon, E., Yvon-Lewis, S., and Zimmer, B.

Venue: AGU Fall Meeting, San Francisco, CA, December 15-19 2008 - Session OS25: Methane Flux from Naturally Occurring Marine Gas Hydrates http://www.agu.org

Abstract: The Department of Energy National Energy Technology Laboratory (DOE/NETL) has recently awarded a project entitled HyFlux: “Remote sensing and sea-truth measurements of methane flux to the atmosphere.” The project will address this problem with a combined effort of satellite remote sensing and data collection at proven sites in the Gulf of Mexico where gas hydrate releases gas to the water column. Submarine gas hydrate is a large pool of greenhouse gas that may interact with the atmosphere over geologic time to affect climate cycles. In the near term, the magnitude of methane reaching the atmosphere from gas hydrate on continental margins is poorly known because 1) gas hydrate is exposed to metastable oceanic conditions in shallow, dispersed deposits that are poorly imaged by standard geophysical techniques and 2) the consumption of methane in marine sediments and in the water column is subject to uncertainty.

The northern GOM is a prolific hydrocarbon province where rapid migration of oil, gases, and brines from deep subsurface petroleum reservoirs occurs through faults generated by salt tectonics (Roberts and Carney 1997). Focused expulsion of hydrocarbons is manifested at the seafloor by gas vents, gas hydrates, oil seeps, chemosynthetic biological communities, and mud volcanoes. Where hydrocarbon seeps occur in depths below the hydrate stability zone (~500m), rapid flux of gas will feed shallow deposits of gas hydrate that potentially interact with water column temperature changes; oil released from seeps forms sea-surface features that can be detected in remote-sensing images (De Beukelaer et al. 2003).

The regional phase of the project will quantify verifiable sources of methane (and oil) the Gulf of Mexico continental margin and selected margins (e.g. Pakistan Margin, South China Sea, and West Africa Margin) world-wide by using the substantial archive of satellite synthetic aperture radar (SAR) images. An automated system for satellite image interpretation will make it possible to process hundreds of SAR images to increase the geographic and temporal coverage. Field programs will quantify the flux and fate of hydrate methane in sediments and the water column.

Related NETL Project
This presentation is related to the NETL project DE-NT0005638, “Remote Sensing and Sea-Truth Measurements of Methane Flux to the Atmosphere". The goal is to obtain accurate measurements of methane flux from the seafloor to the atmosphere with attention to potentially unstable deposits of gas hydrate.

Project Contacts
NETL – Richard (Rick) Baker (richard.baker@netl.doe.gov or 304 285-4714)
Texas A&M University-Corpus Christi – Ian MacDonald (ian.macdonald@tamucc.edu)