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Improving the efficiency of secondary and tertiary oil recovery is one of the major challenges of the crude oil industry. Arguably the most significant advance made in recent years has been the realization of the importance of water chemistry during oil recovery. This has led to the concept of low-salinity waterflooding for conventional oil reservoirs, for which reducing the total salinity of the injection water has been found to improve oil recovery rates. Although the precise mechanisms responsible for the improvements are not completely understood, it is acknowledged that specific interactions in the crude oil/ brine/rock (COBR) systems will modify wettability and interfacial energy. The present paper extends investigations of COBR interactions to higher viscosity oils and considers implications for heavy oil recovery. We have used NMR relaxation time measurements to study interactions in oil/brine/sand (OBS) systems containing either natural bitumen or a polybutene hydrocarbon (Glissopal). Exposing the oil-coated sands to water or aqueous group 1 and group 2 metal chloride solutions enabled the T 2 relaxation time spectrum to be determined as a function of time. The observed decreases in the geometric mean T 2 values with time obey first-order kinetics; for bitumen-coated sands, the rate constants are consistent with diffusion of water through the bitumen. Opto-digital microscopy verified the formation of ∼1−3 μm diameter water droplets in the initially dry bitumen coating, suggesting that water nucleation and growth also occur. This was not observed for the Glissopal-coated sand samples. No evidence was found for displacement of either viscous oil from the sand grains, although optical microscopy did reveal rearrangement of the bitumen coating, which possibly exposes fresh sand surfaces to the aqueous phase. This behavior is consistent with the finding that the original T 2 parameters determined for fresh sand are not fully restored simply by contacting the bitumen-sand surface to water or aqueous salt solutions under the ambient experimental conditions. Glissopal-coated sands exhibited smaller time-dependent T 2 changes compared with bitumen-coated sands. While not displacing viscous oils from the sand surface under the experimental conditions used, it is conjectured that water ingress into the surface oil layer could weaken oil/sand interactions which by analogy with recent studies on conventional oil recovery could provide an additional heavy oil recovery mechanism under more dynamic or higher temperature conditions.

Advances made in recent years have allowed the application of colorants obtained from natural sources into textile dyeing. The use of ultrasound in the dyeing method is reported to increase dye uptake and decrease dyeing times. The aim of this work is to further extend the knowledge of natural hair dyes considering the use of ultrasound in the dyeing method with commercially available herbal dyes and using goat hair as a model for human hair. Optimal ultrasonic parameters were selected by considering the effects of sonication times (5, 10 and 15 min), frequencies (44, 400 and 1000 kHz) and total dyeing times (30, 60 and 120 min) in the morphology of the dyed hair and the colour intensity. Damage to the hair surface was evaluated by scanning electron microscopy (SEM) images, differences in colour of the dyed hair was obtained by ImageJ analysis and quantification of dye uptake was determined by UV-visible spectroscopy. The evidence from this study suggests an increase in goat hair coloration with the use of ultrasonic energy. Optimal dyeing conditions in consideration of colouration efficacy without hair damage were identified as sonication at 400 kHz for 10 min with a total dyeing time of 60 min.

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