Viscosity Reduction Of Heavy Crude Oil Research Articles

Viscosity reduction of heavy crude oil by co-heating with hydrothermal liquid product of cotton stalk

Abstract Hydrothermal process (HT) is an economical and simple method in upgrading agriculture wastes. The liquid product obtained from HT is interesting because of abundant active chemical group. The present work tried to co-heat the HT liquid product of cotton stalk (CS) with heavy crude oil to reduce its viscosity. The optimization study was performed to obtain the best condition of co-heating and mechanism study was completed by comparing the viscosity reduction efficiency and analyzing group composition of crude oil before and after co-heating with HT liquid products of CS, cellulose, hemicellulose and lignin. The results show that the crude oil viscosity reduced obviously after co-heating with CS-HT liquid product under the optimized condition (220°C, 1 h, 3 g treatment liquid, 30 ml crude oil). The preliminary mechanism study results suggest that the main function component of CS that cause viscosity reduction of heavy oil is lignin. The current work provides a new idea of lignocellulosic biomass upgrading and heavy crude oil viscosity reduction.

Heavy crude oil viscosity reduction by dilution with hydrocarbons obtained via pyrolysis of polypropylene and polystyrene

Liquid hydrocarbons obtained from the pyrolysis of polypropylene and polystyrene were used as diluents to reduce the viscosity of a Mexican heavy crude oil of 10.6°API. Blends of oil and diluents were formulated with fractions of 5, 10 and 15 vol% of diluent. Viscosity results were plotted as a function of temperature and diluent volume fractions. The degree of viscosity reduction at room temperature was of 96 – 97% using 15 vol% of the proposed materials. Results show that viscosities lower than 400 cP, the classical maximum for pipeline transportation, are achieved at relatively low temperatures (45 – 65 °C).

Effect of Textural Properties and Surface Chemical Nature of Silica Nanoparticles from Different Silicon Sources on the Viscosity Reduction of Heavy Crude Oil.

The main objective of this study is to evaluate the effect of the textural properties and surface chemical nature of silica nanoparticles obtained from different synthesis routes and silicon precursors, on their interactions with asphaltenes and further viscosity reduction of heavy crude oil (HO). Four different SiO2 nanoparticles were used, namely, commercial fumed silica nanoparticles (CSNs) and three in-house-synthesized nanoparticles (named based on the silicon source) modifying the silicon precursor: sodium silicate (SNSS), tetraethylorthosilicate (TEOS) (SNT), and rice husk (SNRH). The nanomaterials were characterized through dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, N2 physisorption (SBET), atomic force microscopy (AFM), and X-ray photoelectron (XP) spectroscopy (XPS). The adsorption of asphaltenes over the different nanoparticles was evaluated at a concentration of 1000 mg·L–1 in toluene. The asphaltene–nanoparticle interactions are closely related to several textural properties, such as roughness, surface area, and hydrodynamic diameter, as well as the surface chemical nature of the materials. The results in the textural characterization exhibited that the sizes of the nanoparticles from TEM ranged between 6.9 and 11.5 nm. Nevertheless, the standard deviation of the measurements showed that the sizes are statistically similar. Inversely, the hydrodynamic diameter changed, affecting the surface silanol group’s availability due to a hindering effect on functional groups as the hydrodynamic size of the material increased. The rheological measurements were performed at a fixed nanoparticle dosage of 1000 mg·L–1 and showed that the trend of the degree of viscosity reduction (DVR) was CSN > SNT > SNSS > SNRH with the highest value yielding at 30%. The results of DVR are in accordance with the nanoparticles’ adsorptive capacity as higher values were obtained with the material that leads to a higher amount of adsorbed asphaltenes. Also, the oxygen amount related to silanol groups, estimated by the XPS analysis, showed a direct relation regarding adsorption capacity and further HO viscosity reduction.

Experimental study of Iranian heavy crude oil viscosity reduction by diluting with heptane, methanol, toluene, gas condensate and naphtha

Abstract Due to the high viscosity of heavy crude oils, production from these reservoirs is a demanding task. To tackle this problem, reducing oil viscosity is a promising approach. There are various methods to reduce viscosity of heavy oil: heating, diluting, emulsification, and core annular flow. In this study, dilution approach was employed, using industrial solvents and gas condensate. The viscosity of two Iranian heavy crude oils was measured by mixing with solvents at different temperatures. Dilution of both oil samples with toluene and heptane, resulted in viscosity reduction. However, their effect became less significant at higher concentrations of diluent. Because of forming hydrogen bonds, adding methanol to heavy crude oil resulted in higher viscosity. By adding condensate, viscosity of each sample reduced. Gas condensate had a greater impact on heavier oil; however, at higher temperatures its effect was reduced. Diluting with naphtha decreased heavy oil viscosity in the same way as n-heptane and toluene. Besides experimental investigation, different viscosity models were evaluated for prediction of heavy oil/solvent viscosity. It was recognized that Lederer' model is the best one.

Multifunctional Evaluation of a New Supramolecular Complex in Enhanced Oil Recovery, Removal/Control of Organic Damage, and Heavy Crude Oil Viscosity Reduction

The development of new technologies based in the design and application of new molecules to solve problems related to the removal and control of formation damage by organic deposition and viscosity reduction of heavy crude oils as well as to increase the oil recovery factor is an important challenge in the oil industry. This experimental study reports the influence of a novel supramolecular complex on the removal/control of organic deposition and enhanced oil recovery processes through core displacement tests at reservoir pressure and temperature conditions. In addition, its capabilities as viscosity reducers for heavy crude oils are also reported. Three different Mexican brine/rock/crude oil systems were used to evaluate the multifunctional properties of the novel supramolecular complex. Results showed a good performance of the capabilities of the supramolecular complex tested to reduce the viscosity, to remediate organic damage, and to enhance the oil recovery factor. In order to explain the results obt...

Heavy Crude Oil Viscosity Reduction and the Impact of Asphaltene Precipitation

One of the main challenges associated with the production of heavy or extra-heavy crude oil is transportation of the oil by pipelines, particularly without the prior reduction of the oil viscosity to acceptable values to ensure oil fluidity in the pipelines. The reduction of viscosity can be obtained by various sophisticated methods. In this study, we investigated different blending techniques to reduce the viscosity of heavy crude oil. The blending of Middle East heavy crude oil with light crude oil or with one of its distillates, such as kerosene or diesel, as diluents was conducted over the entire range of weight fractions at 20 °C and atmospheric pressure. The heavy oil viscosity was decreased from 4000 to 500 cP, representing an 88% reduction. The experimental data were fitted with an empirical equation, and the results were satisfactory, with an average absolute value of the deviation of 0.0015 cP. A negative performance of the heavy oil with diluent mixtures was identified based on the asphaltene precipitation phenomenon, which was found to depend on not only the type and composition of the diluents used but also the concentration of each diluent. To obtain additional insight into asphaltene precipitation, qualitative studies were performed with scanning electron microscopy imaging and dynamic light scattering. Compared to the other diluents, kerosene distillates performed well with a specific heavy crude oil sample under our testing conditions. The addition of 0.5–2 wt % of a solvent mixture of polar protic hexane-1-ol and nonpolar toluene to the crude oil and diluent mixture was found to successfully delay the precipitation of asphaltene in these low-viscosity mixtures.

Heavy crude oil viscosity reduction and rheology for pipeline transportation

Different methods of reducing the viscosity of heavy crude oil to enhance the flow properties were investigated. Experimental measurements were conducted using RheoStress RS100 from Haake. Several factors such as shear rate, temperature and light oil concentration on the viscosity behavior have been studied. This study shows that the blending of the heavy crude oil with a limited amount of lighter crude oil provided better performance than the other alternatives. Experimental measurements in terms of shear stress τ–shear rate γ ˙ , and yield stress τ 0 were conducted on the mixture of heavy crude oil–light crude oil (O-light). The results showed a significant viscosity reduction of 375 mPa s at a room temperature of 25 °C. This study shows that the heavy crude oil required a yield stress of 0.7 Pa, whereas no yield stress was reported for the heavy crude oil–light crude oil mixture.

Heavy Crude Oil Viscosity Reduction for Pipeline Transportation

The approaches used for reducing the viscosity of a heavy crude include heating, blending with a light crude and with kerosene, and forming oil-in-water emulsions. Heating had a dramatic effect on the heavy crude viscosity, but it failed to achieve a practical level; consequently, blending the heavy crude with either light crude or kerosene was attempted and further reduction was achieved, but substantial amounts of these expensive diluents are required. Alternatively, emulsion formation was carried out, and it was established that a practical level of reduction is achievable at 70-75% oil content, in the high shear rate range, and at 30-50°C. The effect of temperature on the viscosity of the crude oil mixtures and emulsions can be fitted on the American Society for Testing and Materials (ASTM) double-log model with an average deviation of 7.2-9.4%.