Speaker
Description
In the oil and gas industry, the oil recovery efficiency is optimized by injecting water of different ionic composition such as low salinity brine, carbonated brine and other smart fluids into the reservoir to alter the wetting state of the rock thereby increasing recovery. However, the reservoir also contains its in-situ Formation Water (FW), and hence mixing of these two brines of different ionic compositions will result in the formation of scale in an attempt to re-establish a new equilibrium for the mixture. Different ionic compositions were prepared and mixed at a predefined volume fractions at different temperature and pressure conditions to evaluate their scale precipitation tendencies. The experiment was simulated using the qualities and quantities of the brine as used during the experiment using a geochemical solver (PHREEQ-C).
The scale formed due to the interactions of these ions was visually observed and analyzed to evaluate the type of scale. The experiment results were buttress using the geochemical modelling results. A positive saturation index (SI) indicates precipitation while a negative SI indicate dissolution. If the SI is zero, it implies equilibrium (i.e. the Ionics are neither precipitating or dissolving). At 60 °C temperature, pH (solution) = 6.515, Density ≈ 1.00783 g/cm³, and 1atm simulation pressure, both the simulation confirm the formation of aragonite, calcites, halite and witherite. Scale mitigation mainly involves chemical scale inhibitors that prevent mineral deposition. Effective mitigation requires understanding scale type, inhibitor selection, and early treatment to manage and control scaling risks in production systems.