Investigation of Coupled Processes and Impact of High Temperature Limits in Argillite Rock

Technical Report · Fri Aug 15 04:00:00 EDT 2014

DOI:https://doi.org/10.2172/1150013· OSTI ID:1150013

Zheng, Liange ^[1]; Rutqvist, Jonny ^[1]; Steefel, Carl ^[1]; Kim, Kunhwi ^[1]; Chen, Fei ^[1]; Vilarrasa, Victor ^[1]; Nakagawa, Seiji ^[1]; Houseworth, James ^[1]; Birkholzer, Jens ^[1]

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1. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Shale and clay-rich geological formations have been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world, because of their low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures. Permeabilities arising from the primary porosity of these rock types are low because of the extremely fine-grained constituents and the very small pores associated with the fine-grained material. Permeability values are typically less than 10 microdarcies (10-17 m2 or about 10-10 m/s equivalent hydraulic conductivity) and are often two to four orders of magnitude lower. While fractures can occur, clay and shale often demonstrate the tendency to self-seal fractures, which reduces the effects of fractures on bulk permeability. This occurs as a result of swelling from the increased water potential in fractures, the generation of fracture infilling materials and mineral precipitation, and plastic deformation of the rock (Mazurek et al., 2003). The low permeability of clay and shale rock are well-known in the hydrogeology community where these rock types represent aquitards that severely limit groundwater movement, and in petroleum geology, where they act as caprocks limiting the rise of buoyant petroleum fluids. Other favorable characteristics of clay/shale rock are the strong sorptive behavior for many radionuclides and (in saturated systems) the low flow rates, which typically lead to reducing conditions because of the lack of oxygen transport from the surface. Clay and shale rock also act to chemically buffer the effects of materials introduced through repository construction, operation, and emplaced materials (Arcos et al., 2008).

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1150013
• Report Number(s): LBNL--6719E
• Country of Publication: United States
• Language: English

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