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Effect of CO 2 on the buoyancy of geothermal fluids
Author(s) -
Straus Joe M.,
Schubert Gerald
Publication year - 1979
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl006i001p00005
Subject(s) - buoyancy , geothermal gradient , volume (thermodynamics) , convection , thermal , thermodynamics , geology , instability , thermal expansion , thermal instability , mechanics , petrology , geophysics , physics
The presence of large amounts of CO 2 in geothermal fluids is shown to generally enhance convective instability. The buoyancy of water‐CO 2 solutions can be dominated by the large volume changes that occur when CO 2 enters or leaves solution. The transfer of water between the liquid and vapor phases which accompanies the movement of CO 2 into or out of solution also contributes to changes in the fluid volume and resultant buoyancy. The effective thermal expansivity α eff in the CO 2 rich fluid of the Broadlands geothermal region of New Zealand exceeds the coefficient of thermal expansion of ordinary water α ell for depths are large as a 2 km; α eff is more than an order of magnitude larger than α ell at depths less than 500 m.