Utilizing ionic liquids as additives for oil property modulation

Characterization of the wax precipitation in Iranian crude oil based on Wax Appearance Temperature (WAT): Part 1. The influence of electromagnetic waves

A new class of hybrid pour point depressants (PPDs) are developed on the basis of poly(octadecyl acrylate) (POA) functionality and POA/nanosilica hybrid particles. Activity performance is demonstrated using a model waxy oil system consisting of 10 wt % macrocrystalline wax dissolved in dodecane, effectively emulating the essential characteristics of waxy petroleum fluids. Differential scanning calorimetry (DSC) evidence confirms that POA molecules enhance the solubility of wax in the continuous oil phase, reducing the wax appearance temperature. The presence of POA also serves effectively to modulate the crystal morphology to a more regular spherical-like shape, instead of the disc-like morphologies common to pristine paraffin wax crystals, affecting reduced gelation temperatures in accordance with percolation theory predictions. In addition, rheometric yield stresses decrease with increasing dosage rates of POA. A solvent-blending protocol is followed to subsequently prepare POA/nanosilica hybrid particles. Optimal PPD performance of the hybrid particle system is attained at a dosage rate of 100 ppm. At dosages higher than the optimal dose, the gel strength increases in an analogous manner to the directionality of the Einstein equation for viscosity. The POA/nanosilica hybrid particle system provides spherical templates for wax precipitation, resulting in a compact precipitate structure, which suppresses gelation and improves the flowability of the model waxy oil by several orders of magnitude. DSC data confirm that a vast majority of the POA molecules become solubilized in the continuous oil phase upon dispersion of the hybrid nanoparticle system. As such, the free POA molecules enhance wax solubility in the continuous oil phase. Hydrophobic nanoparticles retain a more robust ability to modulate waxy oil rheology at low-dosage rates, as compared to purely polymeric functionality. The primary mechanism of hybrid particle PPDs involves heterogeneous nucleation activity. The hybrid particles effectively provide solid–liquid interface sites as wax precipitation templates, which result in spherical-like spherical wax morphologies. The compact morphologies hinder and suppress the percolation process necessary to form a volume-spanning network of wax crystals. As such, the hybrid nanoparticles constitute effective and economic PPD additives and may serve as the basis for next-generation environmentally friendly wax inhibition agents, by reducing the amount of additives needed.

Foaming characteristics of crude oil-CO2 mixture by depressurization: Influence of crude oil viscosity and wax precipitation

The challenges of waxy oil production in a Russian oil field and laboratory investigations

Thermal behavior of waxy oils is investigated using the techniques of thermogravimetric (TG) analysis and differential scanning calorimetry (DSC). Model waxy oils and real waxy crude oils are utilized. Decomposition temperatures of waxy oils are obtained using TG analysis. The effects of thermal history, wax content, and additive on the gelation process of waxy oils are investigated using DSC. The DSC method provides a measure of wax solubility as well as solid fraction. An integration method and a computation method are utilized to predict solid fraction. In addition, wax crystallization onset points are obtained at the cooling rates ranging from 1 to 20 °C min−1. Similarly, wax dissolution endset points are obtained at heating rates ranging from 1 to 20 °C min−1. Extrapolated onset and endset points yield wax precipitation temperature and wax dissolution temperature, respectively. Subsequently, wax solubility curves are obtained using thermodynamic computations. A wax precipitation temperature method and a wax dissolution temperature method combine thermodynamic phase behavior with onset/endset points to predict solid fraction. Both the wax precipitation temperature method and the wax dissolution temperature method can predict solid fraction of waxy oil samples. The wax precipitation temperature method and the wax dissolution temperature method are accurate when the temperature is close to the wax appearance temperature. A heat-integration method provides accurate values of the solid fraction at temperatures significantly below the wax appearance temperature. Therefore, integration method and wax precipitation temperature/wax dissolution temperature method are combined to predict solid fraction. The effect of solid fraction on yield stress is also investigated using differential scanning calorimetry and rheometry. Finally, a new solid fraction dependent gel strength model is obtained for shut in and restart of waxy crude oil pipelines.

Experimental investigation of the live oil-water relative permeability and displacement efficiency on Kingfisher waxy oil reservoir

Imide anions such as bis(trifluorosulfonyl)amide (TFSA-) have been widely investigated as the most typical perfluoroanion, which forms ionic liquids (ILs) with various onium cations like dialkylimidazolium and the good electrochemical and thermal stability have been attracted attention as a unique liquid electrolyte for secondary batteries especially lithium batteries. [1] Recently, research and developments of post-lithium ion battery, so called next-generation batteries, have been intensively investigated. Especially, the use of multivalent metal as an anode like magnesium, zinc and aluminum have been attracted attention due to their high volumetric energy density. However, in many case, slow diffusion of multivalent cation in a layered oxide cathode might be one of the severe problems. The use of thermally stable and less volatile ionic liquids might be one of the promising choice to enhance the diffusion in a cathode material at enough higher temperature. However, no good magnesium redox have been observed in a conventional and typical ionic liquids containing the TFSA- .[2] In this study, we investigated the electrochemical responses of a magnesium metal and also much cheeper alloy (AZ31B) in a various molten salt such as a conventional TFSA ionic liquids, onium chloride and alkali metal intermediate temperature molten TFSA salt to discuss the reason for the poor redox in a conventional ionic liquids and the effect of the addition of halogenide like chloride.

In this study, effect of ethylene vinyl acetate (EVA) as an inhibitor on wax appearance temperature (WAT) of crude oil in the Iranian oil field has been investigated using differential scanning calorimetry (DSC) method. The effect of EVA on the morphology of crude oil wax crystals has been investigated using a system designed to be equipped with an ocular microscope. The EVA inhibitor has a very good performance in reducing the Wax appearance temperature of crude oil and by adsorbing on the growing wax crystals, it prevents the crystallization process and also their connection to each other to form a network structure. By 800 ppm of the EVA inhibitor, the largest decrease occurred in the WAT of crude oil (at the rate of 26.13 ° C) and also smaller crystals and weaker structures were formed at this concentration. Therefore, 800 ppm of EVA inhibitor was selected as an optimal value

Wax appearance temperatures of vegetable oils determined by differential scanning calorimetry: effect of triacylglycerol structure and its modification

Waxy crude oils are normally found in petroleum reservoirs. Crude oil with the wax formation is one of the crucial problems for flow assurance of pipeline transportation in oil and gas production. This issue can commonly cause wax deposition problem and it has made a huge amount of economic losses such as production, time and maintenance cost. Therefore, it is a critical aspect to deal with wax deposition for crude oil flow assurance, especially at the surface region in cold climate. In this study, n-heptane and poly (maleic anhydride-alt-1-octadecane) or MA as the inhibitors with different concentrations will be measured the effect on pour point, wax appearance temperature and wax deposition of Mae Soon crude oil and investigated the effects of parameters such as temperature, concentration and types of inhibitors for these aspects.
 
 N-heptane plays a key role in the reduction of pour point, wax appearance temperature and wax deposition of this study.� It is also found that the amount of total wax deposits decreases when this chemical concentration increases. Consequently, an increasing concentration provides a better performance for inhibition of wax deposition problems.�On the other hand, MA also shows the results for the reduction of wax appearance temperature and wax deposition of Mae soon crude oil. According to the results, it offers low performance for pour point reduction because it cannot be soluble well in the higher wax content of crude oil. After each individual inhibitor are measured for the reduction of pour point, wax appearance temperature and wax deposition, the mixtures of n-heptane and MA are investigated to have better results for wax deposition prevention. It is found that 10% n-heptane and 5000 ppm MA provides the optimal condition for wax deposition prevention based on this study because it can show low wax deposition with less amount of chemical consumption. The results can be used as fundamental data and the investigation can expand into combination with another type of inhibitors.

Visualization of thermal removal mechanism of paraffin deposits: Providing guidelines for minimum temperature requirements

Chapter 7 - Wax Deposition

A new perspective on the measurements of wax appearance temperature: Comparison between DSC, thermomicroscopy and rheometry and the cooling rate effects

Paraffin wax deposition is the most frequent flow assurance problem in oil production fields. It disrupts stable oil production, and a considerable amount of time and money are spent ameliorating on-site problems. To prevent and mitigate paraffin wax deposition, it is necessary to proactively identify the conditions under which paraffin wax is deposited. Furthermore, monitoring and detection techniques are required to determine the efficacy of the technical measures applied. This study proposes a method based on acoustic velocities obtained by ultrasonic monitoring and detection to estimate the following three temperature elements: (1) wax appearance temperature of oil containing paraffin wax, (2) temperature at which the growth of paraffin wax deposits is activated, and (3) temperature at which the paraffin wax deposits begin to age. An experimental system comprising an ultrasonic transducer and a temperature sensor were set up, and the temperature gradient of the analyzed fluid sample was controlled by continuously circulating an isothermal fluid. Based on real-time monitoring, data measurements were made, and variations in the acoustic velocity of fluid samples were measured. A paraffin wax deposition experiment was conducted using synthetic waxy oil samples with paraffin solid contents of 5 wt.% and 15 wt.%, respectively. Q-factors were calculated based on the spectral ratio method, and wavelet characteristics were analyzed according to temperature changes, to estimate wax appearance temperature. Results show that the method proposed in this study estimates wax appearance temperature in a similar measurement range as conventional methods and enables the life cycle of paraffin wax deposition to be determined through monitoring and detection.

Laboratory analyses of the formation of wax deposits in crude oil are generally performed at atmospheric pressure on stabilized samples without the presence of light components. Therefore, the effects of two important factors that influence the solubility of waxes, namely, light fractions and pressure, are not considered. As a consequence, the results may not reflect what really happens in production lines and equipment. In this work, we evaluated five Brazilian crude oil samples and one condensate, recombined with different gases and under varying pressures, using the high-pressure microcalorimetry technique (HPμDSC). The samples were characterized with regard to the distribution of waxes by the number or carbon atoms to correlate with the results for wax appearance temperature (WAT) and crystallization enthalpy. The results indicate that rising pressure causes the WAT to rise as well and the recombination with gases composed mainly of light hydrocarbons reduces the WAT. Methane has the greatest influence on the oils containing higher amounts of macrocrystalline waxes, an effect that is stronger at higher pressures. Nitrogen does not act as a solvent of the paraffins present, whether of the macro- or microcrystalline type. Fractions lighter than C3, contained in the saturation gas mixtures, are more efficient in the solubilization of waxes, mainly those with lower molar masses. Variations in temperature and enthalpy of crystallization depend upon the pressure, composition of the gas (or mixture of gases), and composition of each crude oil.