Debunking the Impact of Salinity on Crude Oil/Water Interfacial Tension

Abstract

The salt content and composition of the water that is either produced with the oil or injected in an oil reservoir can change the composition of the oil at the oil/water interface. Having identified these compositional changes is key to designing the most optimized water ionic recipe to be used in waterflooding of an oil reservoir. Hence, there is a need to better understand the physicochemical interactions at the oil/water interface because of salinity effects. This study elucidates the effect of salinity on the interfacial interactions through pendant drop measurements of crude oil/water interfacial tension, surface charge evaluation by zeta potential, water content measurements by Karl Fischer titration, Fourier transform infrared (FT-IR), and ultraviolet–visible spectroscopy analyses. The interfacial tension results indicate that the interfacial tension increases with reduction in water salinity, which is shown for the first time by FT-IR and water content measurements to be proportional to the spontaneous formation of water microdispersion as the main mechanism of low salinity water injection. Formation of microdispersions and partitioning of surface-active materials by conjugated acidic compounds and/or acidic asphaltenes and low-molecular weight acidic compounds, respectively, are the main parameters controlling the crude oil/water interactions. Asphaltenes and acidic materials are shown to be the underlying compounds in the crude oil phase promoting the microdispersion formation.

Direct Insight into the Cause and Time Evaluation of Spontaneous Emulsification of Water in Crude Oil during Low Salinity Waterflooding Using Microfluidic Model

“…According to the surface tension measurement results, with decreasing brine concentration, the surface tension of the crude oil and brine increases from 8.91 to 20.64. Some research shows the exact relationship between brine salinity and crude oil–brine salinity . Comparing the values of surface tension with the results of emulsion stability, increasing the surface free energy does not contribute to the stability of emulsions.…”

“…Some research shows the exact relationship between brine salinity and crude oil−brine salinity. 65 Comparing the values of surface tension with the results of emulsion stability, increasing the surface free energy does not contribute to the stability of emulsions. Considering the surface tension values (increasing trend by decreasing salinity), it can be concluded that the change of the surface tension is not an effective mechanism in the formation of emulsions.…”

An anti-oil-fouling superhydrophilic composite aerogel for solar saline alkali water desalination

“…At the same time, the use of large agricultural machinery can lead to waste oil spills as well as pesticides and fertilizers being lost through irrational use during agricultural production, which can produce water pollutants, with the main components being emulsified oil and some long-chain alkanes, such as n-hexane. [3][4][5] Saline alkali water contaminated by oil can affect crop production, mechanical corrosion, and human health. More serious is water scarcity, which endangers human life.…”

Experimental Investigation on the Pore-Scale Mechanism of Improved Sweep Efficiency by Low-Salinity Water Flooding Using a Reservoir-on-a-Chip

“…Reducing the salinity increases the interfacial tension. 24 Sanyal reported the effect of clay mineral on oil recovery during low-salinity water flooding. Both the cations in the brine and kaolinite composition can influence the oil recovery.…”

“…The work showed the release of adsorbed oil not only from the surface of the minerals (pore lining materials) due to wettability change but also from the interlayer surfaces of the clay minerals or spontaneous formation of water microdispersion. Reducing the salinity increases the interfacial tension . Sanyal reported the effect of clay mineral on oil recovery during low-salinity water flooding.…”