| Abstract |
The ratios of gases in dry steam produced from the vapour-dom reservoir of the Unit 15 steam field at The Geysers in Northern California, USA can be explained by a model incorporating mixing between original reservoir vapour and vapori sed reservoir 1 i qui d. However, hydrogen analyses are anomalous in that they are apparently enriched in the produced steam compared with levels predicted by this model. This enrichment appears to be caused primarily by fluid-rock interactions during boiling in the reservoir, although well casing corrosion reactions during production are also contributary. Hydrogen enrichment also appears to be present in the northwestern area of The Geysers and at the vapour-domi nated geothermal systems of Larderel lo, Italy, suggesting i t s occurrence may be widespread. The calculation and interpretation of steam fractions and waterrock interaction models could be significantly affected by this hydrogen enrichment phenomenon. |