Mechanical properties of hydrate-bearing turbidite reservoir in the first gas production test site of the Eastern Nankai Trough

Yoneda, Jun; Masui, Akira; Konno, Yoshihiro; Jin, Yusuke; Egawa, Kosuke; Kida, Masato; Ito, Takuma; Nagao, Jiro; Tenma, Norio

doi:10.1016/j.marpetgeo.2015.02.029

Cited by 226 publications

(128 citation statements)

References 30 publications

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“…The first direct shear measurement made on hydrate-bearing pressure core material was accomplished on the DSC subsection of core 20P, which has S h ¼ 0.27. The undrained peak shear result is within the range of published values given by Yoneda et al (2015). The shear strength, measured with an applied stress of 3 MPa, drops by~30% after hydrate dissociation.…”

Section: Large-strain Properties: Shear Strength and Friction Anglesupporting

confidence: 86%

“…The cone penetrometer results are in agreement with results measured in a triaxial apparatus by Yoneda et al (2015) on a separate Nankai Trough core subsection. Agreement between strength measurements made with and without an applied stress indicates the sediment strength in the high-S h silty-sands is controlled primarily by the presence of hydrate rather than the state of stress.…”

Section: Large-strain Properties: Shear Strength and Friction Anglesupporting

confidence: 85%

“…The sharp drop in tip resistance indicates brittle failure as the specimen fractures ahead of the cone. Brittle failure in high-S h silty-sands is also observed in this study by Yoneda et al (2015). Because cone penetrometers have not been used extensively in hydrate-bearing sands, the empirical parameter N k is chosen based on the work of Beringen et al (1982), who found N k to be in the range of 15e20 in their study of calcareous soils.…”

Section: Instrumented Pressure Testing Chambermentioning

confidence: 57%

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Hydro-bio-geomechanical properties of hydrate-bearing sediments from Nankai Trough

Santamarina

Dai

Terzariol

et al. 2015

Marine and Petroleum Geology

204

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a b s t r a c tNatural hydrate-bearing sediments from the Nankai Trough, offshore Japan, were studied using the Pressure Core Characterization Tools (PCCTs) to obtain geomechanical, hydrological, electrical, and biological properties under in situ pressure, temperature, and restored effective stress conditions. Measurement results, combined with index-property data and analytical physics-based models, provide unique insight into hydrate-bearing sediments in situ. Tested cores contain some silty-sands, but are predominantly sandy-and clayey-silts. Hydrate saturations S h range from 0.15 to 0.74, with significant concentrations in the silty-sands. Wave velocity and flexible-wall permeameter measurements on neverdepressurized pressure-core sediments suggest hydrates in the coarser-grained zones, the silty-sands where S h exceeds 0.4, contribute to soil-skeletal stability and are load-bearing. In the sandy-and clayey-silts, where S h < 0.4, the state of effective stress and stress history are significant factors determining sediment stiffness. Controlled depressurization tests show that hydrate dissociation occurs too quickly to maintain thermodynamic equilibrium, and pressureetemperature conditions track the hydrate stability boundary in pure-water, rather than that in seawater, in spite of both the in situ pore water and the water used to maintain specimen pore pressure prior to dissociation being saline. Hydrate dissociation accompanied with fines migration caused up to 2.4% vertical strain contraction. The firstever direct shear measurements on never-depressurized pressure-core specimens show hydratebearing sediments have higher sediment strength and peak friction angle than post-dissociation sediments, but the residual friction angle remains the same in both cases. Permeability measurements made before and after hydrate dissociation demonstrate that water permeability increases after dissociation, but the gain is limited by the transition from hydrate saturation before dissociation to gas saturation after dissociation. In a proof-of-concept study, sediment microbial communities were successfully extracted and stored under high-pressure, anoxic conditions. Depressurized samples of these extractions were incubated in air, where microbes exhibited temperature-dependent growth rates.Published by Elsevier Ltd.

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Section: Large-strain Properties: Shear Strength and Friction Anglesupporting

confidence: 86%

Section: Large-strain Properties: Shear Strength and Friction Anglesupporting

confidence: 85%

Section: Instrumented Pressure Testing Chambermentioning

confidence: 57%

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Hydro-bio-geomechanical properties of hydrate-bearing sediments from Nankai Trough

Santamarina

Dai

Terzariol

et al. 2015

Marine and Petroleum Geology

204

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“…Solid NGHs are decomposed into liquid water and natural gas during depressurization. This, in turn, may result in a loss of cementation and a corresponding effective stress decrease of hydrate-bearing sediments (HBS) (Hyodo et al, 2013;Song et al, 2014;Yoneda et al, 2015;Kajiyama et al, 2017;Zhang et al, 2017). NGHs have been treated as a potential trigger in submarine geohazards such as wellbore failures, seabed settlements, and submarine landslides (Nixon and Grozic, 2007;Lee et al, 2010b;Maslin et al, 2010;Ning et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Numerical simulations for analyzing deformation characteristics of hydrate-bearing sediments during depressurization

Liu

Zhang

et al. 2017

Adv. Geo-Energ. Res.

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Natural gas hydrates have been treated as a potential energy resource for decades. Understanding geomechanical properties of hydrate-bearing porous media is an essential to protect the safety of individuals and devices during hydrate production. In this work, a numerical simulator named GrapeFloater is developed to study the deformation behavior of hydrate-bearing porous media during depressurization, and the numerical simulator couples multiple processes such as conductive-convective heat transfer, two-phase fluid flow, intrinsic kinetics of hydrate dissociation, and deformation of solid skeleton. Then, a depressurization experiment is carried out to validate the numerical simulator. A parameter sensitivity analysis is performed to discuss the deformation behavior of hydrate-bearing porous media as well as its effect on production responses. Conclusions are drawn as follows: the numerical simulator named GrapeFloater predicts the experimental results well; the modulus of hydrate-bearing porous media has an obvious effect on production responses; final deformation increases with decreasing outlet pressure; both the depressurization and the modulus decrease during hydrate dissociation contribute to the deformation of hydrate-bearing porous media.

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“…The initial conditions of effective confining stress and pore pressure for all of the tested specimens are summarized in Table 3. In this study, we were not able to measure the changes in void ratio during the consolidation stage owing to the difficulty in the Similarly, SM samples from Eastern Nakai Trough showed a porosity of 39.1%-54.1% under confined conditions; in particular, the porosity of the majority of the remolded samples was higher than that of the original samples from the pressure cores [25]. The initial packing conditions of our SM core samples are comparable to previous studies; hence, the obtained strength results are presumed to be valid and are readily expandable.…”

Section: Particle-scale Observations In Scanning Electron Microscope mentioning

confidence: 94%

Geomechanical, Hydraulic and Thermal Characteristics of Deep Oceanic Sandy Sediments Recovered during the Second Ulleung Basin Gas Hydrate Expedition

et al. 2016

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This study investigates the geomechanical, hydraulic and thermal characteristics of natural sandy sediments collected during the Ulleung Basin gas hydrate expedition 2, East Sea, offshore Korea. The studied sediment formation is considered as a potential target reservoir for natural gas production. The sediments contained silt, clay and sand fractions of 21%, 1.3% and 77.7%, respectively, as well as diatomaceous minerals with internal pores. The peak friction angle and critical state (or residual state) friction angle under drained conditions were~26 • and~22 • , respectively. There was minimal or no apparent cohesion intercept. Stress-and strain-dependent elastic moduli, such as tangential modulus and secant modulus, were identified. The sediment stiffness increased with increasing confining stress, but degraded with increasing strain regime. Variations in water permeability with water saturation were obtained by fitting experimental matric suction-water saturation data to the Maulem-van Genuchen model. A significant reduction in thermal conductivity (from~1.4-1.6 to~0.5-0.7 W·m −1 ·K −1 ) was observed when water saturation decreased from 100% to~10%-20%. In addition, the electrical resistance increased quasi-linearly with decreasing water saturation. The geomechanical, hydraulic and thermal properties of the hydrate-free sediments reported herein can be used as the baseline when predicting properties and behavior of the sediments containing hydrates, and when the hydrates dissociate during gas production. The variations in thermal and hydraulic properties with changing water and gas saturation can be used to assess gas production rates from hydrate-bearing deposits. In addition, while depressurization of hydrate-bearing sediments inevitably causes deformation of sediments under drained conditions, the obtained strength and stiffness properties and stress-strain responses of the sedimentary formation under drained loading conditions can be effectively used to assess sediment responses to depressurization to ensure safe gas production operations in this potential target reservoir.

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Mechanical properties of hydrate-bearing turbidite reservoir in the first gas production test site of the Eastern Nankai Trough

Cited by 226 publications

References 30 publications

Hydro-bio-geomechanical properties of hydrate-bearing sediments from Nankai Trough

Hydro-bio-geomechanical properties of hydrate-bearing sediments from Nankai Trough

Numerical simulations for analyzing deformation characteristics of hydrate-bearing sediments during depressurization

Geomechanical, Hydraulic and Thermal Characteristics of Deep Oceanic Sandy Sediments Recovered during the Second Ulleung Basin Gas Hydrate Expedition

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