MANAGEMENT OF NORM IN THE PETROLEUM INDUSTRY Akpojevwa Tega Naomi, october 2016 | Page 25

radium co-precipitates with Sr, Ba or Ca scale forming radium sulphate, radium
carbonate and – in some cases – radium silicate.
The mixing of seawater, which is rich in sulphate, with the formation water,
which is rich in brine, increases the scaling tendency. Also the sudden change in
pressure and temperature or even acidity of the formation water, as it is brought
to the surface, contributes to scale build-up. The build-up of scale on the interior
of a pipe is shown in Figure 2.0. This phenomenon has significant implications
for the production of oil; in this case the capacity of the pipe to transfer oil
would be reduced significantly.
Hard scales from decontamination of contaminated equipment and tubular using
high pressure water systems or mechanical cleaning are considered to contain
the highest levels of radium isotopes (Radium-226, Radium-228, and Radium-
224), (Wilson and Scott, 1992, Godoy and Petinatti da Cruz, 2003, Al-Masri
and Aba, 2005).
The highest concentrations of radium typically are found in scale deposits that
form when dissolved radium co-precipitates with barium, strontium, or calcium
sulphates. These sulphates form hard, insoluble deposits on the inside of piping,
filters, brine disposal/injection wells, and other water handling equipment. Scale
deposits can thicken and may need to be removed by cleaning processes to
ensure that equipment will operate.
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