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TitleGeomechanical study of the Mallik gas hydrate production field trials
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LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorUchida, S; Soga, K; Klar, A; Yamamoto, K
SourceScientific results from the JOGMEC/NRCan/Aurora Mallik 2007-2008 gas hydrate production research well program, Mackenzie Delta, Northwest Territories, Canada; by Dallimore, S RORCID logo (ed.); Yamamoto, K (ed.); Wright, J F (ed.); Bellefleur, GORCID logo (ed.); Geological Survey of Canada, Bulletin 601, 2012 p. 191-204, Open Access logo Open Access
PublisherNatural Resources Canada
Mediapaper; on-line; digital
RelatedThis publication is contained in Scientific results from the JOGMEC/NRCan/Aurora Mallik 2007-2008 gas hydrate production research well program, Mackenzie Delta, Northwest Territories, Canada
File formatpdf
ProvinceNorthwest Territories
AreaMackenzie Delta
Lat/Long WENS-134.5000 -134.0000 69.5000 69.2500
Subjectsfossil fuels; engineering geology; geophysics; hydrocarbons; gas; hydrocarbon gases; hydrate; methane; methane hydrate; petroleum resources; geophysical surveys; gamma ray logging; gamma-ray surveys; seismic surveys; porosity; permeability; geothermics; modelling; production tests; drilling techniques; pressure-temperature conditions; logging techniques; Tertiary; Cenozoic
Illustrationstables; plots
ProgramGas Hydrates
Released2012 12 14 (13:00)
AbstractA coupled thermo-hydro-mechanical analysis was conducted to investigate the geomechanical response of the gas-hydrate-bearing sediments at the Mallik site, Northwest Territories, during the gas hydrate production trials in the winters of 2007 and 2008 on the Aurora/JOGMEC/NRCan Mallik 2L-38 well. The trials were conducted using the depressurization method, which decreases the wellbore pressure to induce gas hydrate dissociation and create a flow gradient into the wellbore. From the results of the simulations, it was found that the depressurization caused large compressive volumetric deformation due to an increase in the effective stresses. In the perforated layer, depressurization caused the gas hydrate to dissociate preferentially in the radial direction due to anisotropic permeability. This preferential dissociation was enhanced by the increase in water permeability due to gas hydrate dissociation. As the pore pressure was reduced, the effective stresses in all directions (i.e. vertical, radial, and circumferential) increased, but the increase in the vertical stress was more than that of the other two stresses, which resulted in an increase in shear mobilization. In the nonperforated layers adjacent to the perforated layer, the soil moved towards the wellbore as a result of the soil deformation in the perforated layer. This led to an increase in the total radial stress in the nonperforated region. In contrast, the sediments in the dissociated layer reduced its stiffness and strength, decreasing the total radial stress. This relative stress difference induced shear stress at the interface between the perforated and nonperforated layers.

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