Hassan Naderi

Effect of Microwave Irradiation on Wax and Asphaltene Content of Heavy Crude Oil

This study examines the effect of microwave irradiation on these precipitates. One 150 ml sample of heavy crude oil from a reservoir in the southwest of Iran, with 12.7765 %wt asphaltene and 7.771 %wt wax content, was subjected to microwave irradiation in developed Fischer assay apparatus for time durations of 5, 10, 15, 20, 25 and 30 minutes. Experimental results show that microwaving for different lengths of time causes changes in wax and asphaltene content. At 15 minutes’ irradiation, the lowest asphaltene content (10.6225 %wt) was observed. The lowest wax content (5.5131 %wt) was found after 10 minutes’ irradiation. These particles, due to their high capacity to absorb microwaves, are severely affected by these waves. The microscopy results of the particle-size analysis (60 %vol. n-heptane) revealed that when irradiation time increased, the range of asphaltene particle sizes decreased. The size range of asphaltene particles in a primary state from 5 µm to 100 µm (54 µm mean particle size) declined after microwave irradiation, and in 30 minutes reached a range of 5 µm to 40 µm (18.5 µm mean particle size). Scanning electron microscopy images of asphaltene particles demonstrate that the microwaves altered the particles’ structure by inducing microcracks.

Application of ultrasonic as a novel technology for removal of inorganic scales (KCl) in hydrocarbon reservoirs: An experimental approach

Inorganic scales are one of the most important causes of formation damage, which causes pressure drops near wellbores; these in turn impair permeability and severely reduce production in oil and gas reservoirs. This paper examines the effectiveness of ultrasonic waves in removing potassium chloride (KCl) scales. Twenty core samples with different permeabilities were exposed to KCl precipitation. After measuring the permeabilities of the saturated core samples, the samples were first subjected to water injection, and then to water injection with ultrasonic wave radiation. At each stage, sample permeabilities were measured and recorded. The results showed that water injection with two pore volumes did not significantly improve permeability, especially in low-permeability core samples. Ultrasonic wave radiation with water could efficiently improve permeability; this result is more obvious for samples with lower permeabilities. SEM images taken from thin sections of the core samples under water injection and water with ultrasonic waves showed that ultrasonic waves distorted the crystal lattice of the KCl scales, causing cracking and delamination. Creation of wormholes in KCl deposits within fractures also resulted from the application of ultrasonic waves. Analysis of chlorine in the output water from core samples in the core-flooding process showed that ultrasonic waves increased the solubility of scales in water, improving the recovery of permeability in the samples. Results of this study show that using ultrasonic waves can be considered a novel and practical method in the removal of inorganic scales in the near-wellbore region of oil and gas reservoirs.

Inhibiting Asphaltene Precipitation Using Microwave Irradiation: Experimental Investigation

This paper discusses the effect of microwaves on the flocculation of asphaltene particles. A sample of Dehlor heavy oil from southwestern Iran was exposed to microwave radiation under anoxic conditions and saturated with helium gas at intervals of 3, 6, and 9 minutes. Then, using a viscometer and normal heptane, the set point of asphaltene flocculation was determined for each sample. The results of the experiments showed that three minutes of exposure to microwave irradiation caused the asphaltene to be flocculated from 34 vol% normal heptanes in the crude sample to 41 vol%. In other words, microwaves inhibited asphaltene aggregation. Based on the results of SARA (Saturation, Aromatics, Resin, Asphaltene) analysis, the largest reduction in asphaltene composition in heavy oil occurred at the 3 min interval. In contrast, at 6 and 9 min, the greatest decrease was observed for resin compounds, which are themselves a natural inhibitor of flocculation. Changes in the structure and reduction of sulfur and nitrogen components of asphaltene also cause microwaves to act as an inhibitor in the flocculation of asphaltene particles. Therefore, reducing the amount of asphaltene compounds and eliminating polar compounds, which is a function of time interval for microwave radiation, delays asphaltene aggregation.

Using ultrasonic as a new approach for elimination of inorganic scales (NaCl): an experimental study

Because inorganic scales reduce permeability near wellbores, they cause an additional pressure drop in this region (skin damage) and reduce production. NaCl precipitation, particularly in gas-producing wells, is one of the formation damage problems which impair the permeability. The use of backwashing water not only requires a large quantity of water, but is also inefficient. This study examined the effect of the ultrasonic waves in NaCl scale removal. Twenty core samples with different permeabilities were saturated with NaCl. After precipitation of NaCl within the cores, the samples were first subjected to water injection and then to water injection with ultrasonic wave radiation. At each stage, the permeability of cores was measured and recorded. Experimental results reveal that applying ultrasonic waves restores the permeability of cores more than water injection alone. In samples with permeability lower than 20, 30–100, 100–700xa0md and cores with permeabilities higher than 1000xa0md, ultrasonic waves recover permeability to 80, 42, 87 and 81%, respectively. In contrast, water injection alone improves permeability to 29, 18.5, 62 and 77%, respectively. The effect of these waves is much more obvious than water injection alone in low-permeability cores. SEM images from cores show that ultrasonic waves destroy the structure of deposits of sodium chloride. This phenomenon is due to propagation of these waves and the resulting temperature increase in the surroundings, which leads to the increased solubility of these scales. After exposure to ultrasonic waves, sodium chloride deposits inside the induced fractures of cores could be removed from the fracture, whereas water injection alone could not wash and remove the deposits from the fracture. According to the results of this paper, ultrasonic waves can be used as a novel and efficient technology in gas wells to remove inorganic scales in the near-wellbore region.