Shape evolution of a water drop in asphaltene solution under weak DC electric fields

The origin of the dramatic increase of the reorientational and structural relaxation rates of single water molecules in clusters of size N = 16, 32, and 64 at T = 200 K, under the influence of an external, relatively weak electric field (~0.5 107 V/cm) is examined through molecular dynamics simulations. The observed effect is attributed not to any profound structural changes, but to the increase of the size of the molecular cage. The response of water to an electric field in this range shows many similarities with the dynamics of water under low pressure. By referring to simulations and experiments from the literature, we show that in both cases the observed effects are dictated by a common mechanism.

This paper summarizes a long series of experiments that have been done on Rydberg states of Rb. The basic experimental technique that has been used is atomic-beam laser spectroscopy which allows both low-resolution and high-resolution studies. Excitation of Rydberg states is provided by single-photon absorption from a suitably frequency-doubled rhodamine $6G$ tunable laser. Detection is done by field ionization and ion counting. These techniques have allowed us to study the critical ionizing field, which has been found to follow classical, hydrogenic behavior closely. Rydberg states of Rb have been observed from $n=28$ up to $n>100$. High-resolution spectroscopic studies have led to measurement of the fine structure for $\mathrm{np}$ levels located between $n=28$ and $n=60$, as well as the isotope shift of the ground state, $\ensuremath{\delta}\ensuremath{\nu}=(172\ifmmode\pm\else\textpm\fi{}15)$ MHz. Anomalies in the intensity ratio of the doublet $5s\ensuremath{-}np$ transitions have been observed and interpreted as relativistic effects. Perturbations by weak and strong dc electric field are reported. In the case of weak electric fields it is possible to evaluate the polarizability. In the case of strong dc electric fields, new phenomena have been observed and analyzed. We also find experimental evidence of selective photoionization in the presence of an appropriate dc electric field, which could have some applications in laser isotope separation. Finally, we give the preliminary results of an experiment on the effect of a strong nonresonant electromagnetic field on high-lying Rydberg states.

In this paper the effects of some ionic liquids elaborated with iron and molybdenum used to upgrade the properties of a heavy crude oil are discussed. The underlying objective is to increase the mobility of the oil in the reservoir reducing viscosity and improving the oil quality (e.g. diminishing the asphaltene and sulfur contents and increasing its °API gravity), using ionic liquids based on iron (10 wt%) and molybdenum (2 wt%) compounds, in a liquid phase homogeneously mixed with heavy crude oil in a batch reactor of 500 ml, at 673 K during 4 hours. The API gravity of a offshore heavy crude oil from the Gulf of Mexico increased from 12.5 until 20, kinematics viscosity decreased from 15,416 to 136.63 cSt at 288.75 K, asphaltene content was reduced from 28.65 to 10.82 wt%, while the sulfur was removed from 5.14 to 2.16%; and the distillation obtained by Simulated Distillation was increased from 48 to 71.2 vol%. Content of aromatics and saturated compounds were increased through the conversion of asphaltenes and resins, which contents decreased from 16.81 to 13.8 wt% and from 28.85 to 10.82 wt% respectively. Finally, the content of total nitrogen was reduced from 780 to 633 ppm in weight which represents a reduction approximately of 20 wt%. In this work upgrading of a heavy crude oil was obtained through the application of the thermal and catalytic hydrocracking with an ionic liquid. This ionic liquid could be applied into the reservoir combined with in-situ combustion process using unconventional wells in order to improve the recovery of heavy crude oil, producing an oil improved in-situ with lower viscosity, being easier their exploitation, increasing the productivity index in wells, and saving costs of transportation and refining at surface.

An analytical criterion is obtained for microwave breakdown of gases that takes into account the different diffusion coefficients of electrons along and perpendicular to the direction of the electric field. Discharge ignition without electron attachment to the gas molecules and in electronegative gases is examined, along with microwave discharge ignition when a weak dc electric field is applied.

Repetitively pulsed nanosecond discharge plasma decay in propane–oxygen gas mixture in the presence of a heating electric field

A new method to study motoneuron regeneration using electromyograms shows that regeneration slows with age in rat sciatic nerve

Demulsifier assisted film thinning and coalescence in crude oil emulsions under DC electric fields

An analytical approach is presented which aids the computation of the photoabsorption spectrum of atomic hydrogen in a weak external DC electric field. Separation constants in the parabolic frame and one of the normalization factors are evaluated by the Telnov algorithm. For matrix elements the series expansion after powers of parabolic coordinates is used. An enhanced precision arithmetic is applied to extract the second normalization factor from the power expansion. The results agree with those from the previous calculations and experiment.

In this paper are discussed the effects of some metallic oxides used to upgrade the heavy crude oil properties. The underlying objective is to increase the mobility of the oil in the reservoir by reducing viscosity and improving the oil quality using alumina supported transition metals and liquid phase transition metals catalysts (derived from either acetylacetonate or alkylhexanoate compounds), both homogeneously mixed with heavy crude oil. This heavy crude oil upgrading is based on the decrement of the asphaltenes, resins, and sulfur contents, and the increment of its API gravity, and strong reduction of viscosity. In the present work the heavy crude oil from the Golf of Mexico was studied. The API gravity was increased from 12.5 to 21-26, the kinematics viscosity was decreased from 18,130 to 100-8 cSt (at 298 K), the asphaltene content was reduced from 26 to 7 wt%, the sulfur was removed in the range of 30 to 60 wt%, and the distillable fraction was increased between 20 to 30 wt%, and determinated by Simulated Distillation and True Boiling Point (TBP).

It has been suggested in several studies that there may be a link between the presence of high asphaltenes content and the foam-ability of oil. However, a systematic examination of the impact of asphaltenes on the performance of solution gas drive, in connection with foamy oil flow, has not been reported. This paper presents an experimental study that addresses this issue. The objective of this work was to examine whether or not the presence of asphaltenes has a strong influence on the performance of foamy solution gas drive. To this end, parallel solution gas drive experiments were conducted using a heavy crude oil from the Lloydminster area and a deasphalted version of the same oil. To eliminate the influence of oil viscosity, the viscosity of the crude oil was reduced to the same level as that of the deasphalted oil by diluting it with a 50–50 mixture of heptanes and toluene. The experiments were carried out in a visual sandpack that permits observation of bubble formation in the sand. The results show that the presence of asphaltenes significantly promotes foamy oil flow. Introduction Noticeable progress in understanding the high efficiency of solution gas drive in heavy oil reservoirs has been made in recent years. However, basic mechanisms and reservoir engineering parameters are still being evaluated(1). Some authors attribute the high efficiency of solution gas drive in heavy oil reservoirs to foam, and the term foamy oil is used to describe the process. The question of how the foam forms and how it helps in improving the production performance remains to be fully answered. In order to explain this high primary production, two main mechanisms have been proposed(1, 2). The first is the increase of the drainage radius of the well by the formation of high permeability channels, called wormholes(3). The second mechanism is the low gas mobility in heavy oil leading to gas retention that helps in maintaining high pressures in the reservoirs. Low gas mobility is explained by the high oil viscosity and its foamy nature. Smith(4) was the first to propose a model in which the gas flow was in the form of micro bubbles dispersed in the oil phase. Subsequently, Maini et al.(5) experimentally observed this dispersed gas phase and called it Foamy Oil. This leads to the discussion of how the foam is formed and its nature, stability and movement in the formation rock. Although the foamy oil flow occurs in all viscous oil systems, irrespective of whether or not the oil contains asphaltenes, it has been suggested that asphaltenes enhance foaminess. Claridge and Prats(6) proposed that bubble stability is related to the asphaltenes adsorption at the gas-oil interface, which protects bubbles against coalescence. However, experimental results on the effect of asphaltenes are conflicting. In micromodel experiments, Bora et al.(7) observed that asphaltenes lower coalescence rates. Tang and Firoozabadi(8) did not observe any differences in comparing crude oil and silicon oil with similar viscosity. Other authors have suggested that foaming and surface properties of crude oils change with the asphaltenes concentration(9–12).

The problems of utilizing heavy crude oil and natural bitumens centre on their high viscosity which makes them difficult to produce, store, transport, and refine. These factors are reflected in costs. World reserves are substantial, however, perhaps as much as 7 trillion† barrels estimated to represent 0·9 trillion barrels of recoverable oil. Nearly 2·1 trillion barrels of heavy crude oil, more than 50% of the world's total reserve, are located in Venezuela largely in the Orinoco Oil Belt. About 75% of the natural bitumen, 2·6 trillion barrels, is located in Canada in the Athabasca, Cold Lake, and Peace River areas of Alberta. Most of the estimated undiscovered heavy crude oil in the world, approximately 630 billion barrels, is outside the US and Canada. Data required to determine the cost of finding natural bitumen and heavy oil are roughly the same as for other mineral commodities. Similarly for recovery costs. The variables are so extensive that dollar amounts have little meaning without qualification. Recovery depends on depth below surface. Near-surface deposits are recovered by mechanical mining. Deeper deposits must be won by thermal means. Transportation by pipeline is feasible only if the viscosity is lowered by partial upgrading, heating, or by the use of diluents. Part of the high cost of refining results from the major investment required for the large installations that are needed for economic rates of production.

Heavy crude oil and bitumen resources are more than double the conventional light oil reserves worldwide. Heavy crude oil and bitumen production is on average twice as capital and energy intensive as the production of conventional oil. This is because of their extremely low mobility due to high viscosity at reservoir conditions alongside the presence of undesirable components such as asphaltenes, heavy metals and sulphur making it more challenging to produce, transport as well as refine. It is well know that pipelines are the most convenient means of transporting crude oil from the producing field to the refinery. However, moving heavy crude oil and bitumen is extremely challenging because of their inability to flow freely. As such, without prior reduction in the heavy crude oil and bitumen viscosity, transportation via pipeline is difficult. This is because of the huge energy (i.e. high pumping power) required to overcome the high-pressure drop in the pipeline due to their high viscosity at reservoir conditions. To reduce this high-pressure drop and cost of transportation, several technologies have been proposed to improve the flow properties of the heavy crude oil and bitumen through pipelines. In this study, different technologies are reviewed and the advantages and disadvantages of each technology are highlighted with the view that the review will provide direction for improvement and development of novel technologies for bitumen and heavy oil transportation via pipelines.

The aggregates of asphaltene and resin molecules play an important role in stabilizing heavy crude oil. Although many experiments are applied to investigate the complex aggregating structure of asphaltene and resin molecules in heavy crude oil, those microstructure and properties are still not clear at the molecular level. As another auxiliary tool, molecular dynamics (MD) simulation can be used to simulate the behavior of asphaltene and resin in the heavy oil droplet or emulsified oil droplet. The simulation results showed the following: (i) Asphaltene and resin molecules can form a netlike structure in heavy oil through face-to-face or edge-to-face stacking interaction, and the aggregating structure is considered to be the main reason that heavy crude oil has high viscosity. (ii) When surfactant molecules were added to the heavy oil phase, the asphaltene molecules moved to the center of emulsified oil droplet from the oil/water interface. The adsorption of surfactant molecules at the interface resulted ...

The article presents experimental results of research concerning the action of weak electric and magnetic fields on physicochemical transformations in samples of hard coal with a previously destabilized microstructure. The actions of electric and magnetic fields are fundamentally different by many parameters. It has been shown that after treatment with a weak electric field, coal posted an electret potential with an anomalously continuous charge relaxation. Compared to untreated coal samples, the rate of methane emission from methane-saturated samples is maximum for long-flame coal and decreases as it approaches anthracite. The electric field stimulates the grinding of microparticles, a decrease in the maximum gas outlet temperature, a decrease in the enthalpy value in the formation of a new phase, and an increase in the chemical activity of treated coal samples. Fundamentally different results were obtained with magnetic stimulation of coals. In X-ray diffractograms of coal powders after magnetic treatment, the values of the maxima of the main peaks are the largest in comparison with the original samples and those treated with an electric field, which is consistent with an increase in the size of microparticles in a magnetic field. There is an increase in the heat of combustion and a decrease (by 5 times) in the loss of coal mass during heating.

It is quite challenging to recover heavy crude oil due to its high viscosity and long chain hydrocarbon contents. In this study the isolation of thermophilic bacterial consortia from crude oil contaminated soil samples and their ability to degrade heavy crude oil were investigated. Thermophilic spore forming bacteria were inoculated with heavy oil in minimal salt media. Maximum growth was observed on 21st day of incubation at 40 °C. Samples were analyzed for biosurfactant production, where a substantial decrease in surface tension and interfacial tension was not observed. A well-assay was used to check the potential of bacterial consortia for oil-clearing zones on oil agar plate with bacterial cultures and their cell-free filtrates. 16S rRNA sequencing of 27 isolates from oil contaminated soil showed that isolates belonged to three classes: Alpha-proteobacteria, gamma-proteobacteria and Bacilli. Scanning electron microscopy showed that the oil utilizing bacteria were rod-shaped with rough surface and fimbria. Gas chromatography analysis of treated oil after 21 days showed that bacterial consortia efficiently degraded heavy crude oil to light hydrocarbons ranging from C11–C27, from initial C37+ carbon chain of untreated controls. These bacterial consortia showed potential in heavy crude oil biodegradation by breaking it down to smaller hydrocarbon composition.