Mineralogical Observations on Carbonate Scaling in Geothermal Wells at Kawerau and Broadlands

Abstract

Variation in the development of prism, scalenohedron and basal pinacoid faces of calcite produces a considerable range in crystal ogy in scale deposi ts, and platy crystals dominated by the basal pinacoid form are not calcite include various combinations of lack of fluid preferential nucleation of prism rather than basal faces on the pipe wall, or rapid absolute growth rates resulting from high degrees of supersaturation (in turn due to primary fluid composition which may also be consequent upon a pressure decrease or temperature increase and/or high mass flow). Mechanisms which could produce platy surface charge effects relative to Several wells which have developed scales exhibiting major compositional variations (Mgcalcite, dolomite, talc) occur principally near the margins of the fields and probably result from Mg, Si-enriched groundwater incursions.