Effect of Nanoparticles on Asphaltene Aggregation in a Microsized Pore

Innovative xanthan gum-based nanocomposites for asphaltene precipitation prevention in shale and carbonate rocks

Asphaltene deposition in porous media creates many challenges in porous media. This study synthesizes ZnO/SiO2/xanthan nanocomposites (NCs) to adsorb asphaltene and reduce its effect on the shale and carbonate rocks. NCs structure is analyzed using SEM, EDX, BET, and FTIR tests. Also, the rocks' surface is analyzed by an atomic force microscopy (AFM) test after 48 and 96 h of contact with 20 ppm NCs and 20 mg asphaltene. Core flooding tests are performed on shale rocks using 20 ppm NCs at 5500, 4000, and 2500 psi at 48 h. Using AFM in calcite and dolomite formations and selecting core flooding tests based on that are new scenarios that followed in this paper. FTIR results confirm asphaltene adsorption on NCs's surface by changing 854 and 962 cm-1 peaks. AFM tests confirmed asphaltene adsorption on NCs surface, too. Average roughness, root mean square roughness, peak to valley roughness, and average size of the shale were higher than the carbonate sheets. At 20 ppm NCs in shale reservoirs, permeability reduction in porous media was increased up to 39.5 %, and asphaltene precipitation decreased from 8.95 and 20.06 wt% to 2.25 and 10.25 wt%, which shows our suggested scenarios were efficient.

Mechanistic understanding of asphaltene precipitation and oil recovery enhancement using SiO2 and CaCO3 nano-inhibitors

Asphaltene precipitation in oil reservoirs, well equipment, and pipelines reduces production, causing pore blockage, wettability changes, and decreased efficiency. Asphaltenes, with their unique chemical structure, self-assemble via acid-base interactions and hydrogen bonding. Nano-inhibitors prevent asphaltene aggregation at the nanoscale under reservoir conditions. This study investigates the effect of two surface-modified nanoparticles, silica, and calcium carbonate, as asphaltene inhibitors and oil production agents. The impacts of these nano-inhibitors on asphaltene content, onset point, wettability, surface tension, and oil recovery factor were determined to understand their mechanism on asphaltene precipitation and oil production. Results demonstrate that these nano-inhibitors can significantly postpone the onset point of asphaltene precipitation, with varying performance. Calcium carbonate nano-inhibitor exhibits better efficiency at low concentrations, suspending asphaltene molecules in crude oil. In contrast, silica nano-inhibitor performs better at high concentrations. Wettability alteration and IFT reduction tests reveal that each nano-inhibitor performs optimally at specific concentrations. Silica nano-inhibitors exhibit better colloidal stability and improve oil recovery more than calcium carbonate nano-inhibitors, with maximum oil recovery factors of 33% at 0.1 wt.% for silica and 25% at 0.01 wt.% for calcium carbonate nano-inhibitors.

Simulation Investigation on the Influence Mechanism of Toluene and Heptane on the Aggregation of Asphaltene Molecules

Asphaltenes are a group of compounds that are soluble in benzene and toluene but insoluble in nonpolar small molecule n-alkanes. The asphaltene aggregation in the asphaltene-heptane-toluene system was studied using molecular dynamics (MD) simulation, and the interaction between asphaltene molecules during this process was also revealed from the evolution of the density field, radial distribution function (RDF), and intermolecular distance of asphaltenes. Three main findings were made: (1) more asphaltene precipitates (heptane) were contained, and more asphaltene dimers or trimers were formed during the MD simulation; (2) asphaltene molecules interacted with each other to form aggregates in the form of π-π or H-bond interaction. The stable distance of the π-π interaction was 3.3-3.5 Å, and the stable distance of the H-bond connection was 1.7-1.9 Å. (3) The asphaltene interaction in the heptane-rich system was dominated by π-π interaction between asphaltene molecules. However, the asphaltene interactions in the toluene-rich system were mainly the π-π interaction between asphaltene molecules and toluene and the H-bond interaction between the side chains of asphaltene molecules. The results of this study can aid in understanding how asphaltene molecules aggregate and self-associate and can also offer theoretical support for flow assurance in systems used to produce crude oil.

Study on the Kinetic Process of Asphaltene Precipitation during Crude Oil Mixing and Its Effect on the Wax Behavior of Crude Oil

As an important component of crude oil, asphaltene precipitation and deposition are harmful to petroleum production and processing. In previous research, the impacts of asphaltene precipitation on crude oil characteristics were preliminarily explored. In this paper, by mixing different types of crude oil, the dynamic process of asphaltene precipitation and its effect on the crystallization and gelation behaviors of mixed crude oil were in-depth analyzed and discussed using the high-speed centrifugation technique, microscopic observation, differential scanning calorimetry (DSC) thermal analysis, and rheological test. The results showed that the asphaltene precipitation mainly occurred in the early stage of crude oil mixing and was influenced by crude oil composition. As the precipitation time increased, the driving force for asphaltene precipitation was gradually weakened until a dynamic equilibrium between asphaltene precipitation and dissolution was reached. Meanwhile, once the asphaltene precipitation occurred, the crystallization and gelation processes of crude oil were significantly affected. It was discovered that the change in the existing state of asphaltenes due to their precipitation is an important factor affecting the interaction of asphaltenes and waxes, which is critical for the technological development of oil and gas flow assurance.

Investigating the Performance of Carboxylate-Alumoxane Nanoparticles as a Novel Chemically Functionalized Inhibitor on Asphaltene Precipitation

In recent years, researchers have attempted to find some practical approaches for asphaltene adsorption and the prevention or postponement of asphaltene precipitation. Among different techniques, nanotechnology has attracted the researchers' attention to overcome the formation damage resulting from the deposition of asphaltenes. In this study, the application of two types of carboxylate-alumoxane nanoparticles (functionalized boehmite by methoxyacetic acid (BMA) and functionalized pseudo-boehmite by methoxyacetic acid (PBMA)) for asphaltene adsorption and precipitation was investigated. First, the synthesis of two functionalized nanoparticles was performed via the sol-gel method. For the assessment of the adsorption efficiency and adsorption capacity of these nanoparticles toward asphaltene adsorption, the batch adsorption experiments applying ultraviolet-visible (UV-Vis) spectroscopy were performed. The Langmuir and Freundlich isotherms were studied to describe the interaction between asphaltene molecules and carboxylate-alumoxane nanoparticles. For determining the "onset" point of asphaltene precipitation, the indirect method, which was based on the difference in the optical property of various solutions containing different concentrations of asphaltene, was utilized by applying UV-Vis spectroscopy. The isotherm models indicate that the adsorption of asphaltene on the surface of nanoparticles is better fitted to the Freundlich isotherm model compared with the Langmuir model. In the presence of PBMA (0.1 wt %), the onset point was delayed around 26, 20, and 17% in the asphaltene concentrations of 1000, 3000, and 5000 ppm, respectively, in comparison with their reference synthetic oils. On the other hand, these postponements for BMA nanoparticles (0.1 wt %) were 17%, 9%, and insignificant for the asphaltene concentrations of 1000, 3000, and 5000 ppm, respectively. The results reveal that two functionalized nanoparticles tend to adsorb asphaltene molecules and have a positive impact on the postponement of asphaltene precipitation due to molecular interactions between the surface of carboxylate-alumoxane nanoparticles and asphaltene molecules. However, PBMA nanoparticles exhibited better performance on the asphaltene adsorption and postponement of asphaltene precipitation, which is related to its smaller size, as well as higher surface area, compared with BMA nanoparticles.

Characterization of bitumen and a novel multiple synergistic method for reducing bitumen viscosity with nanoparticles and surfactants

This paper is concerned with the formation of bitumen during the drilling of the H oilfield in Iraq. The high viscosity and strong adhesion properties of bitumen can influence the drilling operations. Some complex problems include paste screening, and drill pipe sticking, which cause huge economic losses. Therefore, it is necessary to effectively reduce the bitumen viscosity. The contribution of a single subcomponent of bitumen to the viscosity can vary, and the combined effect of different components of bitumen on the viscosity remains unclear. Furthermore, the mechanism of viscosity reduction remains unclear. In this study, the effects of organic solvents on the viscosity of bitumen were studied, and toluene was selected as the best organic solvent. The results showed that aromatics/resins, aromatics/asphaltenes, and resin/asphaltenes can help increase the bitumen viscosity. Novel methods, including the use of nanoparticles, ethyl cellulose, and the quaternary ammonium salt of heptadecenyl hydroxyethyl imidazoline (QASHI), were proposed to decrease the viscosity. TiO₂ and CuO nanoparticles were chosen, and the main factors influencing the viscosity, such as the particle type, concentration, particle size, temperature, and shear rate, were analysed. The results show that the bitumen viscosity decreases with the increase in the concentrations of ethyl cellulose and QASHI. A synergistic effect between ethyl cellulose and QASHI was found with an optimal concentrations of ethyl cellulose and QASHI (1000 and 1600 mg L^-1). A synergistic effect was also observed when nanoparticles, ethyl cellulose, and QASHI were used in combination. This paper reports the micro-mechanism whereby the viscosity of bitumen is decreased.