Prevention of Formation Damage Caused by Mineral Scale Deposition in Carbonate Reservoirs Using Scale Inhibitors

Scale formation is usually occurs during water injection into reservoirs. Inorganic salt deposition causes a permeability reduction and failure of production equipment. In this work, a new inhibitor package was used for preventing scale formation (calcium carbonate and calcium sulfate deposition). To determine the required minimum inhibitory concentration of the developed scale inhibitor, dynamic tube blocking tests were conducted. The new inhibitor could prevent the scale formation at a minimum concentration of 25 mg/L without any pressure drop. The effect of calcium concentrations on the inhibition performance of the developed scale inhibitor, and three different industrial inhibitors was investigated in a range of 200 mg/L to 20000 mg/L. The developed scale inhibitor had the highest inhibition efficiency among the inhibitors. The inhibition efficiency of developed inhibitor was more than 93% at any calcium concentration of the solution under static conditions. Coreflood experiments on carbonate core samples were conducted to study formation damage due to scale formation during waterflooding. In a case of without using scale inhibitor, rock permeability has reached 55% of the initial permeability due to salt precipitation. However, experimental results showed that the permeability remained almost unchanged by use of the developed scale inhibitor.