Shear-induced emulsion droplet diffusion studies using NMR

Ling, Nicholas N. A.; Haber, Agnes; Fridjonsson, Einar O.; May, Eric F.; Johns, Michael L.

doi:10.1016/j.jcis.2015.11.013

Cited by 14 publications

(17 citation statements)

References 51 publications

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“…Our implementation is detailed in a number of publications, 23,24,42,43 the salient features of which are reported here for clarity. With respect to the pulse sequence Energy Fuels XXXX, XXX, XXX−XXX in Figure 4, the acquired NMR signal, S, can be related to the free self-diffusion of molecules (e.g., water), D, via the Stejskal Tanner equation: 44…”

Section: Energy and Fuelsmentioning

confidence: 99%

NMR Studies of the Effect of CO₂ on Oilfield Emulsion Stability

et al. 2016

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Formation of water-in-crude oil emulsions is a pervasive problem for crude oil production and transportation.Here we investigate the effectiveness of a comparatively low pressure CO 2 treatment in terms of breaking these water-in-crude oil emulsions. To this end, we used unique benchtop nuclear magnetic resonance (NMR) technology to measure the droplet size distribution (DSD) of the emulsions. Treatment with 50 bar CO 2 for 2 h resulted in significant emulsion destabilization; this was replicated when CO 2 was replaced by N 2 O, which has a solubility in both the aqueous and oil phases similar to that of CO 2 . Low solubility gases, N 2 and CH 4 , by contrast had no effect on emulsion stability. Treatment with CO 2 was also found to have no effect on a model water-in-paraffin oil emulsion stabilized by a synthetic surfactant (Span 80). Collectively, this supported the hypothesis that emulsion destabilization results from CO 2 precipitation of asphaltenes as opposed to emulsion droplet film disruption during depressurization, which are the two competing theories reported in the literature to explain the observed supercritical CO 2 destabilization of emulsions. Treatment of a water-in-crude oil emulsion featuring partial removal of asphaltenes from the oil phase was consistent with this hypothesis, as the effect of the CO 2 treatment on emulsion destabilization was significantly more pronounced.

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Section: Energy and Fuelsmentioning

confidence: 99%

NMR Studies of the Effect of CO₂ on Oilfield Emulsion Stability

et al. 2016

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“…Tikhonov regularisation has been applied to invert Eq. 3 numerically (Hollingsworth and Johns 2003) and has been successfully demonstrated on a wide range of emulsions in previous work (Fridjonsson et al 2014;Haber et al 2015;Ling et al 2014Ling et al , 2016a.…”

Section: Nmr Theorymentioning

confidence: 90%

“…(Lingwood et al 2012) determined that for the case of restricted diffusion inside spherical droplets, the block gradient pulse (bgp) approximation method is more accurate, where the diffusion is restricted within a spherical geometry and the consequential evolution in magnetisation is modelled using an arbitrary magnetic field based on the general gradient waveform set of methods. The bgp method is detailed elsewhere along with several successful applications to various emulsion systems (Fridjonsson et al 2014;Haber et al 2015;Ling et al 2014Ling et al , 2016a; this data analysis method is employed in this work. Both Eq.…”

Section: Nmr Theorymentioning

confidence: 99%

Effect of hydrate anti-agglomerants on water-in-crude oil emulsion stability

Azizi

Johns

Aman

et al. 2019

J Petrol Explor Prod Technol

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Under high-pressure and low-temperature conditions, gas hydrate shells may form and grow at the interface of water droplets in water-in-oil emulsions. Such hydrate formation can enable downstream agglomeration and slurry viscosification, thus increasing the risk of hydrate blockage. Therefore, emulsion stability represents a critical parameter in understanding this overall flow behaviour. In this study, the impact of three common and widely-used industrial anti-agglomerants from three different suppliers (AA-1, AA-2 and AA-3-exact composition is commercially sensitive) on 30 wt% water-in-oil (W/O) emulsion stability was investigated. Bench-top nuclear magnetic resonance (NMR) pulsed field gradient (PFG) methods were used to measure the droplet size distributions (DSDs) of the W/O emulsions as a complement to bottle stability test. In the absence of hydrate anti-agglomerants, based on visual observation, 85% of the original W/O emulsion remained after 10 h. In the presence of AA-1 and AA-2, 94% of the original emulsion was retained; in contrast, AA-3 acted to destabilise the emulsion with only 64% of the original emulsion visually evident after 10 h. These results were substantiated by PFG NMR measurements which showed substantial changes in droplet size as a function of sample height for the W/O emulsion formulated with AA-3. Interestingly the W/O emulsion formulated with AA-1, while very stable, was characterised by comparatively very large water droplets, indicative of a complex multiple water-in-oil-in-water (W/O/W) emulsion microstructure. AA-2 forms stable emulsion with small droplets of water dispersed in the oil phase. Our results provide insight into a wide range of potential impacts of AA addition on an industrial crude oil pipeline, in which AA-1 resulted in a complex W/O/W multiple emulsion, AA-2 behaved as an emulsifier and AA-3 behaved as a demulsifier.

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“…The relationship between NMR signal and droplet size is significantly more complicated than Equation 1. In the implementation used here, this is achieved via the Block Gradient Pulse (BGP) method [40] which effectively eliminates previous assumptions of a Gaussian phase accumulation in the NMR signal [39] or an infinitely short value for δ [41]. Due to the fact that emulsions consist of a range of droplet sizes, the computation of a droplet size distribution, P ( a ), is required.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Inert Salts on Explosive Emulsion Thermal Degradation

Ling

Fridjonsson

et al. 2021

Propellants Explo Pyrotec

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Ammonium nitrate fuel oil (ANFO) explosive emulsions are comparatively safe, effective and low‐cost products for mining operations. They consist of a supersaturated ammonium nitrate solution dispersed as droplets in a continuous fuel phase. Here we apply a previously developed bench‐top Nuclear Magnetic Resonance (NMR) Pulsed Field Gradient (PFG) technique to monitor the emulsion droplet size distribution in ANFO explosive emulsions as a function of time stored at an elevated temperature of 50 °C; we thus investigate the subtle effect of adverse storage conditions on emulsion stability. Storage at 50 °C for 12 weeks lead to a ∼60 % increase in mean droplet size, whereas a sample stored at 21 °C experienced no change in mean droplet size. The addition of inert salts (calcium nitrate or sodium nitrate) to the ammonium nitrate solution was also considered in terms of their ability to enable stable storage of the emulsions at 50 °C. An addition of 5 wt% calcium nitrate to the aqueous phase was required to suppress any thermal degradation of the explosive emulsions whilst a much lower dosage of only 1 wt% sodium nitrate was required to realise the same stabilizing effect.

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Shear-induced emulsion droplet diffusion studies using NMR

Cited by 14 publications

References 51 publications

NMR Studies of the Effect of CO₂ on Oilfield Emulsion Stability

NMR Studies of the Effect of CO₂ on Oilfield Emulsion Stability

Effect of hydrate anti-agglomerants on water-in-crude oil emulsion stability

The Effect of Inert Salts on Explosive Emulsion Thermal Degradation

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Shear-induced emulsion droplet diffusion studies using NMR

Cited by 14 publications

References 51 publications

NMR Studies of the Effect of CO2 on Oilfield Emulsion Stability

NMR Studies of the Effect of CO2 on Oilfield Emulsion Stability

Effect of hydrate anti-agglomerants on water-in-crude oil emulsion stability

The Effect of Inert Salts on Explosive Emulsion Thermal Degradation

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NMR Studies of the Effect of CO₂ on Oilfield Emulsion Stability

NMR Studies of the Effect of CO₂ on Oilfield Emulsion Stability