Leaching technique using dilute sodium carbonate for permeability increase in granitic rocks

Conference · Wed Dec 01 00:00:00 EST 1976 · EOS, Trans., Am. Geophys. Union; (United States)

OSTI ID:5321169

Potter, J M ^[1]; Balagna, J P; Charles, R W; Vidale, R J

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1. Univ. of New Mexico, Albuquerque

The Los Alamos Scientific Laboratory (LASL) Hot Dry Rock Geothermal Energy downhole system is now thought to consist of two parallel hydrofractures in adjacent wellbores, with a fairly low approximately 10/sup -6/ Darcie permeability between the two fractures. With decreased flow impedance better heat extraction from this system would be possible. Laboratory measurements were undertaken to determine if some type of inexpensive non-corrosive leachant might be used to increase permeability. Sodium carbonate was chosen because of its reactivity with quartz and the ease in which it can be handled in the field. A 1 N Na/sub 2/CO/sub 3/ solution was forced through a granodiorite core in a permeability apparatus at 200/sup 0/C for a period of 14 hours. Permeability was measured prior to and after the use of the sodium carbonate solution. At 200/sup 0/C permeability after leaching was increased approximately an order of magnitude and had become nearly independent of effective confining pressure. The Na/sub 2/CO/sub 3/ solution was analyzed for major elements and the core was examined by Scanning Electron Microscopy to determine the extent of changes in flow channel morphology.

• OSTI ID: 5321169
• Journal Information: EOS, Trans., Am. Geophys. Union; (United States), Vol. 57:12; Conference: AGU fall annual meeting, San Francisco, CA, USA, 6 Dec 1976
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
GRANITES
LEACHING
PERMEABILITY
GRANODIORITES
BOREHOLES
ELECTRON MICROSCOPY
HEAT EXTRACTION
HOT-DRY-ROCK SYSTEMS
HYDRAULIC FRACTURING
QUARTZ
SODIUM CARBONATES
ALKALI METAL COMPOUNDS
CARBON COMPOUNDS
CARBONATES
CAVITIES
CHALCOGENIDES
DISSOLUTION
FRACTURING
GEOTHERMAL SYSTEMS
IGNEOUS ROCKS
MICROSCOPY
OXIDES
OXYGEN COMPOUNDS
ROCKS
SEPARATION PROCESSES
SILICON COMPOUNDS
SILICON OXIDES
SODIUM COMPOUNDS
152002* - Geothermal Data & Theory- Properties of Minerals & Rocks