Mitigation of Mineral Deposition in Carbonate and Sandstone Rocks Using Green Scale Inhibitors

Waterflooding is potentially a viable approach to enhance oil recovery, though its efficacy can profoundly be compromised due to formation damage as a result of inorganic scale deposition. In this study, a series of high-temperature core flooding experiments were conducted to evaluate two green scale inhibitors (SIs) of folic acid and inulin as alternative inhibitors to mitigate mineral deposition. The co-injection of two incompatible brines (with and without SIs) for two flow rates of 0.5 and 3 mL/min into two core samples of dolomite and sandstone was experimentally investigated. The results showed that folic acid would inhibit scale formation as much as 45-49%, at the lower flow rate, compared to inulin with an efficiency of 29-39%, at the higher flow rate. Moreover, computed tomography imaging technique showed that scale formation and fine migration would be dominant mechanisms for formation damage in dolomite and sandstone rocks, respectively. The theoretical study based on surface energy also confirmed the experimental results in terms of the work of adhesion which showed that folic acid would mitigate the calcite deposition on rock surfaces approximately 55%. Finally, a phosphonate-based commercial SI was compared with the green SIs which reaffirmed their potencies.