Physical properties and rock physics models of sediment containing natural and laboratory-formed methane gas hydrate

Abstract

This paper presents results of shear strength and acoustic velocity (p-wave) measurements performed on: (1) samples containing natural gas hydrate from the Mallik 2L-38 well, Mackenzie Delta, Northwest Territories; (2) reconstituted Ottawa sand samples containing methane gas hydrate formed in the laboratory; and (3) ice-bearing sands. These measurements show that hydrate increases shear strength and p-wave velocity in natural and reconstituted samples. The proportion of this increase depends on (1) the amount and distribution of hydrate present, (2) differences in sediment properties, and (3) differences in test conditions. Stress-strain curves from the Mallik samples suggest that natural gas hydrate does not cement sediment grains. However, stress-strain curves from the Ottawa sand (containing laboratory-formed gas hydrate) do imply cementation is present. Acoustically, rock physics modeling shows that gas hydrate does not cement grains of natural Mackenzie Delta sediment. Natural gas hydrates are best modeled as part of the sediment frame. This finding is in contrast with direct observations and results of Ottawa sand containing laboratory-formed hydrate, which was found to cement grains (Waite et al. 2004). It therefore appears that the microscopic distribution of gas hydrates in sediment, and hence the effect of gas hydrate on sediment physical properties, differs between natural deposits and laboratory-formed samples. This difference may possibly be caused by the location of water molecules that are available to form hydrate. Models that use laboratory-derived properties to predict behavior of natural gas hydrate must account for these differences.* E-mail: bwinters@usgs.gov Skorobogatov et al. 1998). Furthermore, some properties of ice and gas hydrate are similar; therefore study of frozen sediment properties may enhance our knowledge of gas hydrate behavior.

Toward Production From Gas Hydrates: Current Status, Assessment of Resources, and Simulation-Based Evaluation of Technology and Potential

“…Initial geomechanical investigations focused on pure compacted CH 4 -hydrates (Durham et al, 2003). Geomechanical properties of laboratory-formed and natural samples have been measured in the GHASTLI apparatus by USGS researchers Winters et al, 2004). Masui et al (2005) conducted some pioneering geomechanical studies using hydrate-impregnated Toyoura sand, developed stress and strain relationships, and defined the relationship between S H and various geomechanical properties (e.g., modulus of elasticity, Poisson's ratio, internal friction angle, etc.).…”

“…Working from a solid foundation of knowledge obtained from earlier studies (Sloan and Koh, 2008;Boswell, 2007), researchers gained a greater understanding of the complexity of hydrate accumulations through laboratory work (Waite et al, 2002;Durham et al, 2003;Winters et al, 2004;Gupta et al, 2006), numerical simulation analyses (Moridis and Reagan, 2007a,b;Moridis and Sloan, 2007), and national and international collaborative field experiments (Dallimore and Collett, 2005) (see discussion in following sections of this paper), and began the development of the precursors to tomorrow's hydrate exploration and evaluation technologies. By 2005, it was clear that, given certain reservoir conditions, production of methane from hydrate was technically feasible and potentially commercially viable through specially tailored application of existing technologies (Boswell, 2007).…”

Methane hydrate stability and anthropogenic climate change

“…Several studies (Clennell et al, 1999(Clennell et al, , 2000 predict inhibition of hydrate formation in fine-grained sediment caused by the high activation energy of forming small crystals in the hydrophobic small cavities of the pore water. This would explain the characteristic textures of hydrate: as pore-filling cement in coarse-grained sediment, but as irregularly shaped masses of pure hydrate in fine-grained sediment, and predicts that hydrates should form first or predominantly in sandy sediments Winters et al, 2004).…”

A Model for the Elastic Modulus of Hydrate-Bearing Sediments

“…Many studies have been conducted in the laboratory by triaxial compression tests to obtain the mechanical data of HBS (Masui et al, 2008;Hyodo et al, 2007;Hyodo, 2013;Miyazaki et al, 2010;Miyazaki and Masui, 2011;Waite et al, 2008Waite et al, , 2009Winters, 1999;Winters et al, 2004;Yun et al, 2007;Zhang et al, 2012a;Song et al, 2010). Different methodologies for sampling methane hydrate (dissolved gas method, partial water saturation method, ice-seeding method, hydrate premixing method) resulted in different hydrate occurrence modes in the pores of sediment (Ecker et al, 2000;Winters et al, 2004).…”

“…Different methodologies for sampling methane hydrate (dissolved gas method, partial water saturation method, ice-seeding method, hydrate premixing method) resulted in different hydrate occurrence modes in the pores of sediment (Ecker et al, 2000;Winters et al, 2004). By the most adopted dissolved gas method, heterogeneous nucleation occurs on the particle surface, subsequently grows into the pore space (pore-filling type), and goes to the final cementation with grains (grain-cementation type).…”