Upscaled Anisotropic Methane Hydrate Critical State Model for Turbidite Hydrate‐Bearing Sediments at East Nankai Trough

Abstract

Turbidite formation is a common feature of natural hydrate‐bearing sediments that has been observed and reported at several hydrate exploration sites. It is therefore important to incorporate this anisotropic geological feature into the constitutive modeling when evaluating the geomechanical risks involved during hydrate‐based gas production. To date, a number of constitutive models have been proposed to capture the isotropic geomechanical behavior of homogeneous hydrate‐bearing sediments. Since the turbidite formation contains soil layers at a scale much smaller than the size of the numerical element used for reservoir scale simulations, it is necessary to upscale the geomechanical behavior of a layered system to an equivalent anisotropic continuum model by adopting some homogenization techniques. In this study, an anisotropic methane hydrate critical state model is developed by modifying the original isotropic version of Uchida et al. (2012, https://doi.org/10.1029/2011JB008661). The calibration methodology of the anisotropic model parameters for a given set of hydrate heterogeneity and the turbidite formation at the Eastern Nankai Trough is proposed and demonstrated. The upscaled parameters are calibrated by curve fitting the numerically simulated stress‐strain curves of the layered system with the original isotropic constitutive model at the layered scale. Forty‐two sets of model parameters are calibrated from different site element models of this site. They are used to develop empirical correlations between the model parameters and the site input properties within the turbidite formation. This paper presents the details of the new anisotropic constitutive model and the performance of the proposed upscaling procedure for the Eastern Nankai Trough case.

Introduction to Special Issue on Gas Hydrate in Porous Media: Linking Laboratory and Field‐Scale Phenomena

“…A third nonlaboratory study relevant for sediment behavior in hydrate reservoirs is focused on the development of a realistic critical state model for turbiditic sediments in the Nankai Trough, where the Japan Oil, Gas and Metals National Corporation conducted the first deep water gas hydrate production test in 2013 (Yamamoto et al, ). Instead of directly measuring sediment physical properties, Zhou et al () use borehole logs and the results of laboratory geomechanical analyses that constrain these properties in order to calibrate a sophisticated anisotropic model. They report that application of this new model within a thermal‐hydraulic‐mechanical (THM) reservoir simulator more closely reproduces the production pattern for water and gas from the 2013 test than does an older, isotropic critical state model.…”

“…A third nonlaboratory study relevant for sediment behavior in hydrate reservoirs is focused on the development of a realistic critical state model for turbiditic sediments in the Nankai Trough, where the Japan Oil, Gas and Metals National Corporation conducted the first deep water gas hydrate production test in 2013 (Yamamoto et al, 2014). Instead of directly measuring sediment physical properties, Zhou et al (2018) 10.1029/2019JB018186…”

“…In the past decade, the THM framework mentioned by Zhou et al () for reservoir simulation has become widely applied in the hydrates community. The THM approach builds on original work by Rutqvist and Moridis () and Rutqvist (), who used variations of the TOUGH+HYDRATE for the thermal and hydraulic components and FLAC for the mechanical part of early generation coupled models of the gas hydrate reservoir.…”

“…Fine-grained particles that are mixed with coarser sediments can be mobilized under certain conditions and are also considered a component of pore fill in some cases. (2018) On the importance of advective versus diffusive transport in controlling the distribution of methane hydrate in heterogeneous marine sediments Lei and Santamarina (2018) Laboratory strategies for hydrate formation in fine-grained sediments (also fines) You and Flemings (2018) Methane hydrate formation in thick sandstones by free gas flow Effect of gas flow rate on hydrate formation within the hydrate stability zone Meyer, Flemings, DiCarlo, You, et al (2018) Experimental investigation of gas flow and hydrate formation within the hydrate stability zone Sahoo et al (2018) Presence and consequences of coexisting methane gas with hydrate under two phase water-hydrate stability conditions Almenningen et al (2018) Upscaled anisotropic methane hydrate critical state model for turbidite hydrate-bearing sediments at East Nankai Trough Ge et al (2018) Laboratory investigation into the formation and dissociation process of gas hydrate by low-field nuclear magnetic resonance technique Role of fines Han et al (2018) Depressurization-induced fines migration in sediments containing methane hydrate: X-Ray computed tomography imaging experiments Hyodo et al (2017) Influence of fines content on the mechanical behavior of methane hydrate-bearing sediments Jang et al (2018) Impact of pore fluid chemistry on fine-grained sediment fabric and compressibility Taleb et al (2018) Hydromechanical properties of gas hydrate-bearing fine sediments from in situ testing Geomechanical and hydraulic properties Spangenberg et al (2018) A quick look method to assess the dependencies of rock physical sediment properties on the saturation with pore-filling hydrate Madhusudhan et al (2019) The effects of hydrate on the strength and stiffness of some sands Kossel et al (2018) The dependence of water permeability in quartz sand on gas hydrate saturation in the pore space Gil et al (2019) Numerical analysis of dissociation behavior at critical gas hydrate saturation using depressurization method Cook and Waite (2018) Archie's saturation exponent for natural gas hydrate in coarse-grained reservoirs Zhou et al (2018) Upscaled anisotropic methane hydrate critical state model for turbidite hydrate-bearing sediments at East Nankai Trough Coupled numerical modeling Sánchez et al (2018) Coupled numerical modeling of gas hydrate-bearing sediments: From laboratory to field-scale analyses Kim et al (2018) Methane production from marine gas hydrate deposits in Korea: Thermal-hydraulic-mechanical simulation on production wellbore stabilit...…”

Experimental Study on Mechanical Properties of Hydrate-Bearing Sand: The Influence of Sand-Water Mixing Methods

“…Uneven distribution of hydrate will cause the heterogeneity of the sample, lowering its representativeness. Zhou et al [23] proposed an advanced soil model to better represent the heterogeneous structure of the hydrate-bearing sediments, and gave more accurate mechanical responses for numerical simulation. Liu et al [24] modeled specimens with uneven hydrate distributions, simulated the triaxial compression test process of the specimens using the discrete element method, and confirmed that the heterogeneity of hydrate distribution has great impacts on the mechanical properties of HBS.…”