Volume change associated with formation and dissociation of hydrate in sediment

[1] Gas hydrate formation and dissociation in sediments are accompanied by changes in the bulk volume of the sediment and can lead to changes in sediment properties, loss of integrity for boreholes, and possibly regional subsidence of the ground surface over areas where methane might be produced from gas hydrate in the future. Experiments on sand, silts, and clay subject to different effective stress and containing different saturations of hydrate formed from dissolved phase tetrahydrofuran are used to systematically investigate the impact of gas hydrate formation and dissociation on bulk sediment volume. Volume changes in low specific surface sediments (i.e., having a rigid sediment skeleton like sand) are much lower than those measured in high specific surface sediments (e.g., clay). Early hydrate formation is accompanied by contraction for all soils and most stress states in part because growing gas hydrate crystals buckle skeletal force chains. Dilation can occur at high hydrate saturations. Hydrate dissociation under drained, zero lateral strain conditions is always associated with some contraction, regardless of soil type, effective stress level, or hydrate saturation. Changes in void ratio during formation-dissociation decrease at high effective stress levels. The volumetric strain during dissociation under zero lateral strain scales with hydrate saturation and sediment compressibility. The volumetric strain during dissociation under high shear is a function of the initial volume average void ratio and the stress-dependent critical state void ratio of the sediment. Other contributions to volume reduction upon hydrate dissociation are related to segregated hydrate in lenses and nodules. For natural gas hydrates, some conditions (e.g., gas production driven by depressurization) might contribute to additional volume reduction by increasing the effective stress.

[1]  Gerald D. Holder,et al.  The Potential of Natural Gas Hydrates as an Energy Resource , 1984 .

[2]  Ming Zhu,et al.  Frost heave modelling using porosity rate function , 2006 .

[3]  J. Santamarina,et al.  THE IMPACT OF HYDRATE SATURATION ON THE MECHANICAL, ELECTRICAL, AND THERMAL PROPERTIES OF HYDRATE-BEARING SAND, SILTS, AND CLAY , 2008 .

[4]  J. F. Nixon.  Discrete ice lens theory for frost heave in soils , 1991 .

[5]  Sayuri Kimoto,et al.  A chemo-thermo-mechanically coupled numerical simulation of the subsurface ground deformations due to methane hydrate dissociation , 2007 .

[6]  Tae Sup Yun,et al.  Observations related to tetrahydrofuran and methane hydrates for laboratory studies of hydrate‐bearing sediments , 2007 .

[7]  Tae Sup Yun,et al.  Mechanical properties of sand, silt, and clay containing tetrahydrofuran hydrate , 2007 .

[8]  J. F. Nixon,et al.  The Residual Stress in Thawing Soils , 1973 .

[9]  C. Ruppel,et al.  Permeability evolution during the formation of gas hydrates in marine sediments , 2003 .

[10]  Joo-yong Lee,et al.  Hydrate-bearing sediments: Formation and geophysical properties , 2007 .

[11]  Jean-Marie Konrad,et al.  Effects of applied pressure on freezing soils , 1982 .

[12]  Pierre Henry,et al.  Formation of natural gas hydrates in marine sediments 1. Conceptual model of gas hydrate growth conditioned by host sediment properties , 1999 .

[13]  Kunio Watanabe,et al.  Observation of Frost Heave of THF Clathrate Hydrate on Porous Glass Powder , 2006 .

[14]  Tae Sup Yun,et al.  Thermal conductivity of hydrate‐bearing sediments , 2009 .

[15]  P. Schultheiss,et al.  OBSERVED GAS HYDRATE MORPHOLOGIES IN MARINE SEDIMENTS , 2008 .

[16]  Hitoshi Tomaru,et al.  Three-dimensional distribution of gas hydrate beneath southern Hydrate Ridge: Constraints from ODP Leg 204 , 2004 .

[17]  B. Buffett,et al.  Formation of gas hydrate from dissolved gas in natural porous media , 2000 .

[18]  Yoshihiro Masuda,et al.  ANALYSIS OF THE JOGMEC/NRCAN/AURORA MALLIK GAS HYDRATE PRODUCTION TEST THROUGH NUMERICAL SIMULATION , 2008 .

[19]  P. Flemings,et al.  Passing gas through the hydrate stability zone at southern Hydrate Ridge, offshore Oregon , 2006 .

[20]  J. Konrad,et al.  Influence of freezing temperature on hydraulic conductivity of silty clay , 2000 .

[21]  Anthony J. Gow,et al.  Effect of Freezing and Thawing on the Permeability and Structure of Soils , 1979 .

[22]  Gye-Chun Cho,et al.  Gas hydrate dissociation in sediments: Pressure‐temperature evolution , 2008 .

[23]  Y. Nakata,et al.  Shear Behavior of Methane Hydrate-bearing Sand , 2007 .

[24]  J. T. Holden,et al.  Heat and mass flow associated with a freezing front , 1981 .

[25]  T. Collett.  Energy resource potential of natural gas hydrates , 2002 .

[26]  J. Rutqvist,et al.  Geomechanical response of permafrost-associated hydrate deposits to depressurization-induced gas production , 2009 .

[27]  W. A. Slusarchuk,et al.  Determination of Some Frozen and Thawed Properties of Permafrost Soils , 1973 .

[28]  R. M. Owen,et al.  Dissociation of oceanic methane hydrate as a cause of the carbon isotope excursion at the end of the Paleocene , 1995 .

[29]  Nikolay I. Shiklomanov,et al.  Subsidence risk from thawing permafrost , 2001, Nature.

[30]  E. R. Pullman,et al.  Thaw Settlement in Soils of the Arctic Coastal Plain, Alaska , 2007 .

[31]  Edward C McRoberts,et al.  Pore Water Expulsion during Freezing , 1975 .