Water inflow into boreholes during the Stripa heater experiments
During the operation of three in-situ heater experiments at Stripa, Sweden, groundwater flowed into many of the instrumentation and heater boreholes. These flows were recovered and measured routinely. The records of water inflow indicate two origins: inflow attributed to local hydrological pressure gradients, and water migration from cracks closing under the rapidly increasing, thermal-induced stress changes. The latter component appeared as a main pulse that occurred when the heaters were turned on, and lasted about 30 to 40 days, steadily declining over the next several months, and decreasing sharply when heater power was decreased or stopped. The magnitude of the total inflow per hole ranged over more than five decades, from 0.1 to over 10,000 liters over the 500 to 600 day time periods. When plotted against the logarithm of total volume, the frequency distribution displays a normal curve dependence with a mean of approximately 10 liters. Of this amount, 1 to 2 liters of flow into 38-mm-diam boreholes accompanied an increase in applied heat load. These amounts are compatible with rock porosities of a fraction of one percent. Inflow into the 3.6 and 5.0 kW heater holes peaked within 3 to 6 days after heater turn on, then declined to zero inflow, with no further inflow measured for the remainder of the experiments. In the heater holes of the time-scaled experiment, which operated at 1.125 kW or less, the initial pulse of inflow took much longer to decay, and 7 of 8 heater holes continued to flow throughout the experiment. The packing off and isolation of a borehole some 40 m distant in the ventilation drift dramatically increased the inflow into the heater holes in one of the three heater experiments. This demonstrated the existence of permeable flow paths among a number of boreholes. The records of water inflow demonstrate the need for a thorough understanding of the nature of fluid flow and storage in fractured crystalline rock.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA); Svensk Kaernbraenslefoersoerjning AB, Stockholm
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6011862
- Report Number(s):
- LBL-12574; SAC-35; ON: DE83015722
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
58 GEOSCIENCES
580100 -- Geology & Hydrology-- (-1989)
BOREHOLES
CAVITIES
DATA
EUROPE
EXPERIMENTAL DATA
FLUID FLOW
GRANITES
GROUND WATER
HYDROGEN COMPOUNDS
IGNEOUS ROCKS
INFORMATION
NUMERICAL DATA
OXYGEN COMPOUNDS
PLUTONIC ROCKS
REMOVAL
ROCKS
SCANDINAVIA
SWEDEN
WATER
WATER INFLUX
WATER REMOVAL
WESTERN EUROPE