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Hydrate-Bearing Clayey Sediments: Morphology, Physical Properties, Production and Engineering/Geological Implications
Project Number
DE-FE0009897
Last Reviewed Dated
Goal

The primary goal of this research effort is to contribute to an in-depth understanding of hydrate bearing, fine-grained sediments with a focus on investigation of their potential for hydrate-based gas production.

Performer

Georgia Tech Research Corporation, Atlanta GA

Background

Fine-grained sediments host more than 90 percent of global gas hydrate accumulation. Yet hydrate formation in clay-dominated sediments is less understood and characterized than other types of hydrate occurrence. There is an inadequate understanding of hydrate formation mechanisms, segregation structures, hydrate-lense topology, system connectivity, and physical macro-scale properties of clay-dominated hydrate-bearing sediments. This situation hinders further analyses of the global carbon budget as well as engineering challenges/solutions related to hydrate instability and production.

Research on hydrate-bearing clay-dominated sediments is needed to enhance fundamental understanding of hydrate formation and resulting morphology, develop laboratory techniques to emulate “natural” hydrate formations in this type of material, develop and assess analytical tools to predict physical properties, evaluate engineering and geological implications, and advance understanding of the potential for gas production from these sediments.

Impact

The project will add significant data and knowledge to the body of hydrates science. An enhanced understanding of the occurrence and behavior of hydrates in clay-dominated sediments will inform discussions of both the role of hydrates in the global carbon cycle and the potential feasibility of production from a portion of the hydrate resource base not currently considered producible.

Accomplishments (most recent listed first)

Key findings from this detailed investigation into the nature and behavior of fine grained hydrate bearing sediments include the following:

Hydrate Formation and Morphology in Fine-Grained Sediments

  • Hydrate nucleation in small pores is limited by guest molecules
  • Hydrate morphology in fines is segregated, mainly governed by mechanical equilibrium
  • Hydrate phase boundary shifts due to both pore size, pore shape, and effective stress
  • Gas supply for hydrate formation comes by diffusion and gas-driven fracture
  • Freshly formed hydrate is highly porous and structured
  • Gas hydrate morphology is not equivalent to that found in initial ice lenses
  • Mineral surface and capillarity affects hydrate formation

Physical Properties of Hydrate in Fine Grained Sediments

  • Dominant morphology is particle-displacive; dominant interface is rough and jagged
  • Assumptions in effective media models are extremely important
  • Physical properties vary with hydrate lens orientation, volume fraction, and the total number of lenses
  • Strength is increased through sediment consolidation and hydrate cementing, but decreased due to particle slippage
  • Over-consolidation leads to altered physical properties
  • The morphology of THF hydrate in kaolinite is governed by mechanical and
    thermodynamic conditions
  • The self-consistent model (patchy) is still effective in predicting the small-strain stiffness of heterogeneous specimens like hydrate-bearing clayey sediments
  • High acoustic damping in hydrate-bearing sediments is most likely caused by high damping hydrate crystals; the quality factor (i.e., damping) of s-wave is effective in quantifying hydrate saturation particularly for heterogeneous and anisotropic specimens

Gas Production from Hydrate in Fine Grained Sediments

  • Capillarity hinders gas production
  • Capillarity and effective stress govern the gas percolation patterns
  • Chemical stimulation is constrained by chemicals injected and ability to transport
  • Depressurization approach to production for hydrates in fine grained sediments: pressure drop occurs within limited zone in sediments with low permeability
  • High stress in the system leads to porosity decrease, which leads to high capillarity and low gas flow rate
  • Overall, potential production of gas from hydrate contained in fine grained sediments is extremely challenging and is impacted by a number of different factors in this type of system
  • Surface mining after thermal stimulation is a potential strategy of harvesting methane from hydrate-bearing clayey deposits, but would require extensive further validation and assessment of peripheral impacts
Current Status

(January 2018)
All activity under the project has been completed and project results are documented in a final scientific/technical report, which can be accessed from the additional information section below.

Project Start
Project End
DOE Contribution

$627,393

Performer Contribution

Cost Share Contribution: $182,774

Planned Total Funding: $810,167

Contact Information

NETL – Richard Baker (Richard.Baker@netl.doe.gov or 304-285-4714)
Georgia Tech – Sheng Dai (Sheng.Dai@ce.gatech.edu)

Additional Information

Final Scientific / Technical Report [PDF-5.9MB] February 2018

Research Performance Progress Report [PDF-635KB] July - September, 2017

Research Performance Progress Report [PDF-331KB] April - June, 2017

Research Performance Progress Report [PDF-886KB] January - March, 2017

Research Performance Progress Report [PDF-632KB] October - December, 2016

Research Performance Progress Report [PDF-280KB] July - September, 2016

Research Performance Progress Report [PDF-866KB] April - June, 2016

Research Performance Progress Report [PDF-3.17MB] January - March, 2016

Research Performance Progress Report [PDF-1.72MB] October - December, 2015

Research Performance Progress Report [PDF-1.65MB] July - September, 2015

Research Performance Progress Report [PDF-5.22MB] April - June, 2015

Research Performance Progress Report [PDF-4.97MB] January - March, 2015

Research Performance Progress Report [PDF-414KB] October - December, 2014

Research Performance Progress Report [PDF-9.71MB] July - September, 2014

Research Performance Progress Report [PDF-5.00MB] April - June, 2014

Research Performance Progress Report [PDF-2.51MB] January - March, 2014

Research Performance Progress Report [PDF-2.24MB] October - December, 2013

Research Performance Progress Report [PDF-1.08MB] July - September, 2013

Research Performance Progress Report [PDF-899KB] April - June, 2013

Research Performance Progress Report [PDF-1.13MB] January - March, 2013

Research Performance Progress Report [PDF-1.13MB] October - December, 2012