Mineral
scale formation has become a serious problem during various
energy production processes, such asgeothermal energy, power production
(cooling towers), or oil and gas operations. Most scales are treated
with threshold scale inhibitors. Several crystallization and inhibition
models have been reported to predict the minimum inhibitor concentration
(MIC) needed to control the barite and calcite scales. Recently, more
attention has been paid to the formation of celestite scales in the
oilfield. However, no models have been developed to predict the MIC
needed for celestite scale control. In this study, the induction time
of celestite under wide ranges of celestite saturation index (SI =
0.7–1.9), temperature (T = 25–90 °C),
ionic strength (IS = 1.075–3.075 M), and pH (4–6.7)
without and with one phosphonate inhibitor (diethylenetriamine penta(methylene
phosphonic acid), DTPMP) and two polymeric inhibitors (phophinopolycarboxylate,
PPCA and polyvinyl sulfonate, PVS) was measured by a laser apparatus.
Based on our experimental results and literature data, a new semiempirical
celestite crystallization and inhibition model has been developed
based upon readily available parameters such as celestite SI (or other
brine compositions) and T. Good agreement between
the experimental results and calculated results from the model was
found. Using this semiempirical model, the MIC needed for three commonly
used inhibitors, DTPMP, PPCA, and PVS, on celestite scale control
can be predicted over extensive production conditions. The developed
model can fill the knowledge gap in scale management strategies for
celestite in the produced waters.