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Title: The evolution of seafloor venting from hydrate-sealed gas reservoirs

Journal Article · · Earth and Planetary Science Letters

Here we use 3D seismic data to show that three rows of seafloor gas mounds can be traced downward to leak points that lie at the hydrate-gas contact within three individual dipping coarse-grained sand bodies in the Terrebonne Basin, Walker Ridge block 313, northern Gulf of Mexico. We predict the overpressure within the sand bodies by assuming that the gas pressure at the vent points equal the least principal stress. We interpret that free gas accumulates at the base of the hydrate stability zone, trapped by the overlying sand which has a high methane hydrate saturation. The free gas accumulates until the gas pressure at the base of the hydrate stability zone reaches the least principal stress in the overlying mudrock, whereupon hydraulic fractures form and fluids are vented to the surface. The warm rising fluids and perhaps localized exothermic formation of hydrate raise the local salinity and temperature. This process progressively shifts the base of the hydrate stability zone to shallower depths and dissociates the hydrate seal within the sand, which creates new leak points and results in the observed migration of the seafloor vents. Within the southwest corner of the Terrebonne Basin, this process has repeated multiple times within the Blue, Orange, and Green sands. Here this study shows how the hydrate stability zone can influence the location of fluid expulsion and in turn be affected by the warm, rising, saline fluids sealed by hydrate.

Research Organization:
University of Texas, Austin, TX (United States)
Sponsoring Organization:
USDOE Office of Fossil Energy (FE)
Grant/Contract Number:
FE0023919
OSTI ID:
1977105
Journal Information:
Earth and Planetary Science Letters, Journal Name: Earth and Planetary Science Letters Journal Issue: C Vol. 579; ISSN 0012-821X
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

References (40)

The evolution of methane vents that pierce the hydrate stability zone in the world's oceans: EVOLUTION OF METHANE VENTS journal August 2014
The interaction of climate change and methane hydrates: Climate-Hydrates Interactions journal February 2017
Evidence for a thick free gas layer beneath the bottom simulating reflector in the Makran accretionary prism journal February 2000
Gas hydrate and free gas volumes in marine sediments: Example from the Niger Delta front journal May 1997
Seafloor sealing, doming, and collapse associated with gas seeps and authigenic carbonate structures at Venere mud volcano, Central Mediterranean journal July 2018
Cold-seep carbonates of the middle and lower continental slope, northern Gulf of Mexico journal November 2010
Passing gas through the hydrate stability zone at southern Hydrate Ridge, offshore Oregon journal January 2006
A prediction of the longevity of the Lusi mud eruption, Indonesia journal August 2011
The El Arraiche mud volcano field at the Moroccan Atlantic slope, Gulf of Cadiz journal July 2005
Geological controls on focused fluid flow associated with seafloor seeps in the Lower Congo Basin journal October 2007
Fluid flow features in hydrocarbon plumbing systems: What do they tell us about the basin evolution? journal December 2012
Relationship between fluid-escape pipes and hydrate distribution in offshore Sabah (NW Borneo) journal January 2018
Gaia's breath—global methane exhalations journal April 2005
Gas hydrate resource potential in the Terrebonne Basin, Northern Gulf of Mexico journal June 2012
Pore- and fracture-filling gas hydrate reservoirs in the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II Green Canyon 955 H well journal June 2012
Gulf of Mexico Gas Hydrate Joint Industry Project Leg II logging-while-drilling data acquisition and analysis journal June 2012
Occurrence and nature of “bottom simulating reflectors” in the northern Gulf of Mexico journal June 2012
Architecture of gas-hydrate-bearing sands from Walker Ridge 313, Green Canyon 955, and Alaminos Canyon 21: Northern deepwater Gulf of Mexico journal June 2012
Electrical anisotropy of gas hydrate-bearing sand reservoirs in the Gulf of Mexico journal June 2012
Subsurface gas hydrates in the northern Gulf of Mexico journal June 2012
Resource and hazard implications of gas hydrates in the Northern Gulf of Mexico: Results of the 2009 Joint Industry Project Leg II Drilling Expedition journal June 2012
Review of progress in evaluating gas hydrate drilling hazards journal June 2012
Seismic characteristics of fluid escape pipes in sedimentary basins: Implications for pipe genesis journal August 2015
Seafloor and buried mounds on the western slope of the Niger Delta journal May 2017
Gas hydrate reservoirs and gas migration mechanisms in the Terrebonne Basin, Gulf of Mexico journal September 2017
Widespread occurrence of methane seeps in deep-water regions of Krishna-Godavari basin, Bay of Bengal journal February 2021
Formation of natural gas hydrates in marine sediments: 1. Conceptual model of gas hydrate growth conditioned by host sediment properties journal October 1999
Feeding methane vents and gas hydrate deposits at south Hydrate Ridge: FEEDING METHANE VENTS AND GAS HYDRATES journal December 2004
Making calderas from mud journal August 2008
Evidence for massive emission of methane from a deep‐water gas field during the Pliocene journal October 2020
Subsurface fluid flow in the deep-water Kwanza Basin, offshore Angola journal January 2016
Internal structure and eruptive history of a kilometre-scale mud volcano system, South Caspian Sea journal January 2007
Deep pore pressures and seafloor venting in the Auger Basin, Gulf of Mexico: Pore pressures and venting in the Auger Basin journal April 2010
Review of submarine cold seep plumbing systems: leakage to seepage and venting: Seeps plumbing system journal March 2012
Critical pressure and multiphase flow in Blake Ridge gas hydrates journal January 2003
How tectonic folding influences gas hydrate formation: New Zealand’s Hikurangi subduction margin journal December 2018
Petrophysical properties of the Green Canyon Block 955 hydrate reservoir inferred from reconstituted sediments: Implications for hydrate formation and production journal September 2020
Seal bypass systems journal August 2007
Reservoir pressure and seafloor venting: Predicting trap integrity in a Gulf of Mexico deepwater turbidite minibasin journal February 2005
Effective stress constraints on vertical flow in fault zones: Learnings from natural CO2 reservoirs journal August 2019