Impact of Polar Components on Crude Oil-Water interfacial Film Formation: A Mechanisms for Low-Salinity Waterflooding

Abstract

AbstractLow salinity waterflooding is a promising Improved Oil Recovery (IOR) process showing growing activity since discovery. However, incremental recovery over traditional waterflooding varies significantly. Numerous investigations have attempted to prove or disprove recovery mechanisms associated to this process. In our earlier research, we proposed that buildup of the crude oil-brine film viscoelasticity leads to suppression of trapping mechanisms during low-salinity waterflooding. We also advanced the idea that film response depends upon combined characteristics of both crude oil and water. In this paper, interfacial viscoelasticity measurements were conducted on several Wyoming crude oils as well as processed versions of the same oils with selected asphaltene content. Dual-wall ring shear rheology and pendant-drop dilational rheology were run to investigate the connection between polar content in the oil and interfacial viscoelastic response. To further investigate the connection between the interface viscoelasticity and low-salinity waterflooding mechanisms, coreflooding experiments intended to minimize geochemical events during flooding were completed using Berea sandstone. Oil recovery and pressure responses were monitored as well. Film viscoelasticity results turned out consistent with our hypothesis, namely that high content of polar components leads to high viscoelasticity of the crude oil-water interfacial film. Carefully selected coreflooding experiments were run and these results were combined with our earlier ones to unveil recovery trends. Our observations show that a good relationship exists between polar component content and interfacial viscoelasticity, and consequently with oil recovery factor, but outlying results, though favoring low-salinity waterflooding, indicate that a more complex set of interactions need to be further investigated. The conclusions of our work support an additional mechanism for low salinity waterflooding that should improve industry's ability to select candidates for this process by directing fluid-fluid characterization efforts not frequently executed at present.