Scale Inhibition

What is scaling induction time?

One of the premier issues in the oil and gas industry is scale deposition which occurs due to changes in process conditions, such as pressure and temperature changes, dissolved gases, or incompatibility between mixing waters, resulting from waterflooding processes and chemical treatment operations. Usually, these processes are performed to maintain sustainable hydrocarbon production at oil, gas, or gas condensate fields. The most common oilfield scales are sulfates such as CaSO₄ (anhydrite, gypsum), BaSO₄ (barite), SrSO₄ (celestite), and CaCO₃ (calcite). In contrast, iron oxide, sulfide, carbonate, and calcium naphthenate scales are less common and generally found in sour crudes.

The formation of mineral scale from an oversaturated solution involves two distinct stages: nucleation, a stage of solid formation via a reaction between the dissolved constituents, and crystal growth, a stage during which the solid grows via a reaction/aggregation with the dissolved nucleus. The duration of this process can reasonably be estimated by the “induction time,” which is classically defined as the time that passes from the creation of oversaturation regarding a solid phase and the detection of that phase in the system due to precipitation.