3D numerical model evaluation of packer tests for hydraulic characterisation of fractured rock

Rock permeability is an essential parameter for the long-termsafety performance of a repository of radioactive high-level waste (HLW). To characterise hydraulic properties of fractured rock and to determine this important parameter, hydraulic tests with a single or multiple packer system in the deep borehole were carried out in Beishan, Gansu Province, NW China-the most potential site for China's geological repository for high level radioactive waste. In the granitic rock, fractures do often exist in form of a network. If water was injected into the packed-off interval, where fracture network was observed, the water demonstrates complex flow regime due not only to the single fracture properties (aperture, roughness, permeability) but also to the fracture furcation. Within a Chinese-German co-operation program between BRIUG and BGR, fracture data from deep geological borehole from Beishan site has been analyzed. These data are from the core mapping and borehole scanning. On the basis of the geological analysis, a fracture network model is therefore built. 3D numerical model including fracture network, borehole interval, and packer is built to be used to interpret the data from the water injection test. Different flow regime in a fracture network has been analyzed.