| Abstract |
Boiling of the deep chloride fluid in the Broadlands geothermal system results in separation of a vapour phase rich in gas (largely CX3 and H S ) . The vapour condenses in to shallow grou?idwater$ over and adjacent to the deep upflow, with the gases being absorbed in to the steam-heated water. This results in Co - rich waters at temperatures of -140 to 180?C at de&hs of 200 to 500 m (Fig. 1). Corrosion of production casing has been noted in some Broadlands wells, and has been attributed to the presence of the CO - rich steam-heated waters. In order to better uderstand the chemistry of these corrosive fluids, downhole samples have been.taken from marginal wells with a Klyen sampler, modified to seal in the high gas content. Before opening the bottle after retrieval, the gases are bubbled through caustic. The total CO in the downhole sample is determined by dking into account the Co2 captured by the caustic. This results in a calculated pH as low as 5.7 in the 140 to 180?c steam-heated waters. |