Large volumes of naturally jointed Precambrian crystalline rock can be stably maintained at pressures considerably above the least principal earth stress in the surrounding rock mass. At Los Alamos National Laboratory’s Fenton Hill hot dry rock (HDR) geothermal test site, tests carried out for a cumulative period of 11 months in the deeper and larger of the two HDR reservoirs showed no evidence...

In the middle of the 1980s, the so-called Hot Dry Rock (HDR) projects were under consideration, aiming at exploiting the heat stored in deep rocks by circulating heat-bearing fluids in closed loops through fracture networks artificially created in the rock by hydraulic fracturation. The typical geological targets of such projects were hot, and therefore necessarily deep crystalline massifs, whi...

A geochemical study was conducted to obtain a comprehensive understanding of fluoride concentration increase in groundwater from a crystalline (hard-rock) aquifer in a small Indian agricultural watershed, where groundwater is intensively abstracted for paddy irrigation. A reactive1-D geochemical model using PHREEQC was used to reproduce fluoride concentrations under rice paddies taking into acc...

Methane is a powerful greenhouse gas, of which most produced by microorganisms in process called methanogenesis. One environment where methanogenic occur the deep biosphere. The biosphere comprises variety ecosystem settings; marine habitats such as subseafloor sediments, rock pore volumes within basalts, and terrestrial settings sedimentary rocks crystalline bedrock fracture networks. Microbia...

A combination of subsurface borehole imaging data and drilling logs were used to characterize the fractures and lithology in 40 bedrock wells at the fractured-rock research site in the Mirror Lake area in Grafton County, New Hampshire. The purpose of the research was to determine whether subsurface lithology and fractures have an effect on the hydraulic conductivity of the crystalline-rock aqui...

Characterization of Excavation Damaged Zone (EDZ) around an underground excavation is a major research topic for deep geological disposal of medium to high level radioactive waste. Rock fracturing due to excavation and thermal loading and its resultant rock mass permeability change in the EDZ are important aspects in the EDZ characterisation. A new function to predict rock mass permeability cha...