The production, utilization and/or reinfection of brine found in geothermal
reservoirs are often hampered by serious and very unique scale problems. Some of
these scale problems are so severe that entire field operations are endangered.
Effective scale management requires on-line monitoring of scaling tendencies as well
as detection and identification of scale deposits.  Laboratory determinations of
real-time scale deposition were recently reported using a radiotracer technique, an
attenuated total reflection sensor, a rotating disk electrode technique, tapered
optical fibers, a piezoelectric sensor and an ultrasonic technique. In addition,
various nuclear attenuation techniques for the in-situ detection of mineral scale in
actual production systems have been also reported recently. In particular, a handled
device was developed to detect the presence of scale in surface piping by measuring
the nuclear attenuation across the pipe diameter and two field cases were presented
in which a  dual-energy-venturi multiphase flow meter was used to detect and
characterize scale according to the attenuation of the nuclear spectrum. A gamma-ray
attenuation method, based on continuous triple-energy gamma-ray attenuation
measurements, for the detection of scale deposition in real-time in oilfield
production tubulars has also been presented recently. The last method was actually an
extension of previous work that had been applied to several field cases of surface
pipe scale detected by dual-energy attenuation  measurements. The method enables a
simple monitoring device to detect and characterize scale in its earliest stages of
formation.

The objective of this work is to present the state-of-the-art in detecting mineral
scaling in geothermal operations using various nuclear techniques. In that respect, a
gamma transmission (attenuation) technique and a gamma emission (radiotracer)
technique were designed and evaluated in the lab for the real-time measurements of
scale formation under flow conditions.

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