Features of fractures forming flow paths in granitic rock at an LPG storage site in the orogenic field of Japan

Yoshida, Hidekazu; Maejima, T.; Nakajima, Shuichi; Nakamura, Yuriko; Yoshida, Shizuo

doi:10.1016/j.enggeo.2012.10.007

Cited by 27 publications

(16 citation statements)

References 21 publications

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“…This granitic body has been selected as the host rock for an LPG storage facility (Yoshida et al . ). Detailed fracture mapping and structural characterization have been carried out during the excavation of the access galleries and storage caverns within this facility.…”

Section: Methodsmentioning

confidence: 97%

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Long‐term stability of fracture systems and their behaviour as flow paths in uplifting granitic rocks from the Japanese orogenic field

et al. 2012

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In granitic rocks, fracture networks typically provide pathways for groundwater flow and solute transport that need to be understood to assess the long‐term performance of deep underground storage or disposal facilities such as radioactive waste repositories. However, relatively little is known about the long‐term processes of fracturing and/or the longevity of flow paths (FP) in granitic rocks distributed within orogenic belts. To clarify these issues, Japanese plutons of different ages and in situ fractures in granite at the Mizunami Underground Research Laboratory (MIU) located in central Japan were studied. Detailed structural characterization and geochemical analysis of in situ fracture fillings sampled from a depth of 300 m were carried out to clarify the relationship between fracturing and mineral infilling processes. Different plutons show identical episodes of fracturing and fracture filling, consisting of: brittle tensile fracturing, due to decreasing temperature through the ductile–brittle transition after plutonic intrusion (Stage I); relatively rapid uplifting (ca. a few mm/year) accompanied by hydrothermal water circulation, which produced uncrushed layered mineral fillings (Stage II); and a period of low‐temperature meteoric water circulation following exposure after uplift (Stage III). The parageneses of carbonate mineral fracture fillings and their carbon isotopic compositions (14C, δ13C) show that there were distinct episodes of carbonate mineral precipitation during the rapid uplifting of a pluton. The carbonate minerals that formed during each episode incorporated carbon from a distinct source. The evolution of fillings identified here enables development of a specific model of fracturing and persistence of fluid‐conducting systems in the plutons of the orogenic field.

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Section: Methodsmentioning

confidence: 97%

“…; Yoshida et al . ). Variations in groundwater geochemistry at the LPG site are also closely related to the distribution of FPs identified in the site.…”

Section: Methodsmentioning

confidence: 97%

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Long‐term stability of fracture systems and their behaviour as flow paths in uplifting granitic rocks from the Japanese orogenic field

et al. 2012

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“…It is important to clarify how these Fe oxyhydroxides will behave after closure of the repository. , 2011, , 2005, 2007;Ishii et al, 2010Iwatsuki et al, 2005, 2007, , 2005a, 100 , 2013, Oyama et al, 2008Yoshida et al, 2013aYamamoto et al, 2013LPG , 2008X , 2004Cornell and Schwaltman, 2003 (Table 1). (a) and (b) show ferric oxyhydroxide formed at shallow depth (30 m below the ground surface in the quarry) and at great depth (210 m deep in drill hole DH-5R1), respectively, in the Toki granite.…”

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confidence: 99%

“…Se, Tc, Pd, U, Np, Pu , 1999a;Kitamura et al, 2010Oyama et al, 2008 1 2 m Tokiwa et al, 2013, 1999aSKB, 1993Posiva, 1999Iwatsuki et al, 2002; 2005 LPG Liquefied Petroleum Gas Yoshida et al, 2013a Fig. .…”

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confidence: 99%

Ferric oxyhydroxide in underground geological environments and high-level radioactive waste disposal: Analysis of influence on nuclide migration scenarios

英一

鋼志

2014

Jour. Geol. Soc. Japan

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Ferric oxyhydroxide in subsurface geological environments may influence the long-term natural barrier function with respect to nuclide migration at potential sites of disposal of high-level radioactive wastes (HLW). Here, samples of ferric oxyhydroxide from the subsurface environment of Japan were studied in order to ( ) evaluate suitable repository depths that will need to be characterized; and ( ) assess how ferric oxyhydroxide will need to be treated with respect to nuclide migration at a future repository site. Analysis of the ferric oxyhydroxide provides the following insights into site characterization and the rock barrier function: ( ) ferric oxyhydroxide formed along a connective fracture network that extends from the surface to deep levels, but there is a depth limit of oxidation due to geochemical buffering by redox reactions; ( ) early-stage ferric oxyhydroxide remains stable even after the environment returns to reducing conditions; and ( ) ferric oxyhydroxide produced in the rock matrix can contribute to retarding nuclide migration by sorbing radionuclides and clogging micropores. The results show that ferric oxyhydroxide formed in the geological environment may influence the geosphere barrier function in and around subsurface repository caverns for the disposal of HLW in Japan.

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The Effective Transmissivity of a Plane‐Walled Fracture With Circular Cylindrical Obstacles

Jasinski

Dąbrowski

2018

JGR Solid Earth

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Stimulated and propped fractures provide the conductive pathways in low matrix permeability rocks. We study the impact of fracture aperture and proppant size and fraction on the effective transmissivity of a stimulated fracture filled with a partial monolayer of proppant grains. The proppant grains are treated as circular cylindrical obstacles, and the fracture walls are planar. The key geometric parameters are the obstacle fraction f and the ratio between the fracture aperture and the obstacle diameter α. We use three‐dimensional Stokes flow numerical simulations to demonstrate that the fracture flow model given by the Reynolds equations may largely overestimate the flow rate. To circumvent the inability of the Reynolds model to fulfill the no‐slip boundary condition at the rims of the obstacles, we use the Brinkman flow model adapted to the case of fracture flow. The relative difference between the effective transmissivities computed with the Stokes and Brinkman models for systems with multiple obstacles is below 10% for fractions up to 0.5. We use the Brinkman model to study the effective transmissivity of a plane‐walled fracture with circular cylindrical obstacles. Systematic numerical simulations show that the normalized effective transmissivity is predominantly dependent on f and α, and the effects of obstacle ordering are minor. The presented numerical results can be used by petroleum engineers for estimating transmissivities of propped fractures under in situ conditions. The model can also be applied to microfluidic systems and for deriving first‐order estimates of the effective transmissivity of rough‐walled, natural fractures with load‐bearing contact areas.

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Features of fractures forming flow paths in granitic rock at an LPG storage site in the orogenic field of Japan

Cited by 27 publications

References 21 publications

Long‐term stability of fracture systems and their behaviour as flow paths in uplifting granitic rocks from the Japanese orogenic field

Long‐term stability of fracture systems and their behaviour as flow paths in uplifting granitic rocks from the Japanese orogenic field

Ferric oxyhydroxide in underground geological environments and high-level radioactive waste disposal: Analysis of influence on nuclide migration scenarios

The Effective Transmissivity of a Plane‐Walled Fracture With Circular Cylindrical Obstacles

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