Deposition of calcium carbonate mineral scale from crude oil can be a serious production problem. The ENERCAT tool minimizes the deposition of this scale by transforming calcite to aragonite both downhole and at the surface. Unlike paraffin and ashphaltene that require The ENERCAT installation at depth, calcium carbonate mineral scale can be prevented at surface temperatures and pressures.
The Science Hypothesis
The science behind The ENERCAT’s reduction of scale is that it transmits waves that are resonant with low-frequency vibrational motions of the brine component of bulk crude oil fluid. The ENERCAT utilizes physics to drive chemistry influencing the transformation of calcite to aragonite. The molecular oscillation frequencies of The ENERCAT are ‘tuned’ to match the frequencies of the crude oil brine.
This increases the amplitude of the brine’s oscillations at preferred frequencies providing the energy necessary to cause aragonite to form instead of calcite. The waves transmitted by The ENERCAT drive low-frequency vibrational motions of the bulk fluids that favor the formation of crystal polymorphs that have a high probability of remaining in solution.
Characteristics of Calcite and Aragonite Polymorphs
Calcium carbonate can adopt several crystal polymorphs (see figure below). The two most common are calcite and aragonite. Since they both contain the same ions, they also have the same charges, but the charges are not distributed the same in each crystal polymorph due to differing crystal structures. Calcite’s charge distribution covers most of its trigonal crystal surfaces, causing more attraction between crystals. Consequently, calcite has a high probability of depositing on pipeline materials especially metal.
The charge distribution of aragonite on the other hand, is localized, occurring at the ends of its long and thin orthorhombic acicular crystals causing less attraction between crystals. This results in a high probability of aragonite remaining dispersed in the solution and exhibiting properties of a lubricant in some cases. Installation of The ENERCAT yields oil brine samples that are dominated by aragonite polymorph of calcium carbonate that remain dispersed in the solution.