Inhibition of scale buildup during produced-water reuse: Optimization of inhibitors and application in the field

摘要

Inhibition of scale buildup and optimization of the selected compound inhibitor were investigated during the recycling and reuse of oilfield produced-water. Particular attentions were paid to the factors of scale inhibition, and the changes of scale phase composition and morphology. The results showed that the addition of Zn~(2+) ions can effectively inhibit the process of corrosion, and then reduce scale growth. A dispersing agent was required to buffer against the adhesion of crude oil with the precipitates. The compound inhibitor (ratio of PBTCA, HEDP and ATMP, 2:2:1) achieved a higher efficiency of scale inhibition (97.34%) than any of the inhibitors individually. Moreover, structural anomalies of the crystals also revealed significant differences in the presence and absence of the compound inhibitor. The results proved that the pipelines first corrode, then, mechanical impurities, residual petroleum hydrocarbons and calcium scale gradually attach to the corrosion point to form a dirt scale layer. After n periods, a bedding black-and-white scale layer forms. During the field trial, it was found that dosing the compound inhibitor at 70 ppm results in a 92.46% inhibition efficiency (IEs) at 85 °C Therefore, the compound inhibitor could be applied to prevent the buildup of scale during produced-water reuse.