The effect of agitation and temperature on crystallization of calcium carbonate in water injection process

Water injection is a common method for enhancing oil recovery from oil reservoirs. However, there is a possibility of forming different precipitations when the injected water and the formation water are combined and this will result in serious problems in the reservoirs. In this study, we investigated the behavior of calcium carbonate precipitation in different conditions of temperature and agitation. At 25 °C and without agitation, it took 6 hours to reach the maximum amount of precipitation. With increasing the temperature to 80 °C, this time decreased to 2 hours. At 25 °C and 80 °C in with agitation condition, the maximum amount of precipitation formed in 2 hours. The results showed that increasing temperature and agitation will result in more amount of calcium carbonate precipitation in less time. The SEM (Scanning Electron Microscope) and EDX (Energy Dispersive X-Ray) analyses were used to identify type, size of the crystals, and elements of the obtained precipitations. The SEM analysis showed that agitation and temperature can decrease the size of the crystals. The results of this study help us to choose the appropriate strategy to prevent the negative consequences such as reservoir permeability reduction and blockage in surface facilities and aquifer areas.