Impact of Brine Salinity, Exposure Time, and Rock–Oil–Brine Interactions on Asphaltene Instability

Experimental evidence suggests that, alongside thermodynamic conditions, physicochemical interactions among oil, brine, and rock components can trigger asphaltene instability during water-based oil recovery processes, ultimately leading to formation damage. However, published studies fail to consider all relevant parameters at the same time. Consequently, this research addresses this critical research gap by analyzing the influence of individual and combined parameters (such as brine/rock type, exposure duration, and rock/oil/brine ratio) on asphaltene instability. A systematic series of static tests was conducted utilizing different brines to create water-in-oil emulsions with varying quantities of dispersed carbonate and sandstone particles at distinct exposure durations. Ultraviolet–visible (UV–vis) spectroscopy was utilized to indirectly evaluate the asphaltene content in aged oil phases that had interacted with brine. The results of analysis of variance (ANOVA) reveal that, unlike rock type, other effective parameters such as brine type, brine/oil volume ratio, rock/brine ratio, and exposure time have an independent effect on asphaltene stability. However, except for the rock/brine ratio and exposure time, there are no meaningful mutual effects among these factors. The stability of asphaltenes is also influenced by both the type and salinity of brine, with higher salinity conditions leading to increased adsorption of asphaltenes onto the rock surface- especially carbonate particles-compared to sandstone particles. The impact of the exposure time on asphaltene instability is more significant in the first 10 days. The trends observed in interfacial tension (IFT), Fourier transform infrared spectroscopy (FTIR), zeta-potential, and UV–vis absorbance collectively support and validate the findings and aid in optimizing the oil recovery process and reducing the associated formation damage.