Essential role of structure, architecture, and intermolecular interactions of asphaltene molecules on properties (self-association and surface activity)

Sacrificing Surfactants to Improve Oil Recovery: A Fluid Density Functional Theory Study

In the chemically enhanced oil recovery (CEOR) processes, heavy components in crude oil, such as asphaltenes, adhere to reservoir rocks, significantly impeding crude oil extraction. Surfactants are frequently utilized to improve oil recovery due to their ability to reduce interfacial tension (IFT) and modify surface wettability. Nevertheless, indiscriminate surfactant usage may result in resource wastage and hinder the attainment of optimal recovery outcomes. Therefore, it is urgent to accurately and efficiently screen out optimal surfactants suitable for different oil fields. This work employs fluid density functional theory (FDFT) to investigate the competitive adsorption mechanism of surfactants and asphaltenes on rock interfaces. We examined the impact of surfactants on asphaltene adsorption and determined the optimal surfactant concentration and chain length for differing reservoir electrical properties and asphaltene compositions. Furthermore, a comprehensive assessment of surfactants was conducted, considering both performance and economic factors. The findings contribute to a deeper comprehension of the displacement effect of surfactants on asphaltenes and offer scientific screening solutions for surfactants in oil recovery processes.

Comprehensive review of enhanced oil recovery strategies for heavy oil and bitumen reservoirs in various countries: Global perspectives, challenges, and solutions

This study presents a comprehensive review of enhanced oil recovery (EOR) methods tailored specifically for high permeable heavy oil/bitumen (HOB) reservoirs, encompassing reservoir properties, production techniques, and associated challenges. In contrast to existing literature, this research uses a novel approach by delving into the production history and methodologies employed in prominent HOB-producing countries. As a result, some comprehensive primary reservoir threshold criteria are created via coupling the presented information in various literatures. Also, the analysis reveals diverse global strategies for HOB production. Canada's majority of HOB reservoirs, with average gravity less than 11 API, employ surface mining and cold production with sand. Russia's higher gravity HOB reservoirs face challenges with combustion methods. Venezuela emphasizes multilateral horizontal wells and EOR methods like down-hole electrical heaters, surfactant injection and thermal methods. In the USA, a novel downhole steam generation method shows promise. Argentina focuses on Centenario formation production with steam injection and polymer/gel treatment after water flooding, while China utilizes cyclic steam stimulation (CSS), Fire flooding and integrated technologies after water flooding. Oman's Marmul field uses polymer and alkaline-surfactant-polymer flooding for water-cut reduction while Sudan employs infill horizontal wells, deeper re-completion, cement squeezing, partially perforating for the same purpose. As a final conclusion, surface mining is prevalent for low-depth bitumen reservoirs, whereas cold methods are preferred during the early stages of heavy oil production. Furthermore, among the EOR methods, CSS has the biggest share in oil production specially in Colombia (Middle Magdalena basin), Canada (Athabasca field) and China. These findings underscore the importance of tailoring extraction methods to the unique characteristics of each HOB reservoir for optimal production efficiency. By leveraging insights from global production histories and innovative techniques, substantial improvements in oil recovery and operational efficiency can be achieved, paving the way for sustainable utilization of this vital energy resource.

Density functional theory investigation of the contributions of π-π stacking and hydrogen bonding with water to the supramolecular aggregation interactions of model asphaltene heterocyclic compounds

CONTEXT

A complex supramolecular process involving electrostatic and dispersion interactions and asphaltene aggregation is associated with detrimental petroleum deposition and scaling that pose challenges to petroleum recovery, transportation, and upgrading. The homodimers of seven heterocyclic model compounds, representative of moieties commonly found in asphaltene structures, were studied: pyridine, thiophene, furan, isoquinoline, pyrazine, thiazole, and 1,3-oxazole. The contributions of hydrogen bonding involving water bridges spanning between dimers and π-π stacking to the total interaction energy were calculated and analyzed. The distance between the planes of the aromatic rings is correlated with the π-π stacking interaction strength. All the dimerization reactions were exothermic, although not spontaneous. This was mostly modulated by the strength of the hydrogen bond of the water bridge and the π-π stacking interaction. Dimers bridged by two water molecules were more stable than those with additional water molecules or without any water molecule in the bridge. Energy decomposition analysis showed that the electrostatic and polarization components were the main stabilizing terms for the hydrogen bond interaction in the bridge, contributing at least 80% of the interaction energy in all dimers. The non-covalent interaction analysis confirmed the molecular sites that had the strongest (hydrogen bond) and weak (π-π stacking) attractive interactions. They were concentrated in the water bridge and in the plane between the aromatic rings, respectively.

METHODS

The density functional ωB97X-D with a dispersion correction and the Def2-SVP basis set were employed to investigate supramolecular aggregates incorporating heterocycles dimers with 0, 1, 2, and 3 water molecules forming a stabilizing bridge connecting the monomers. The non-covalent interactions were analyzed using the NCIplot software and plotted as isosurface maps using Visual Molecular Dynamics.

Asphaltene Adsorption on Solid Surfaces Investigated Using Quartz Crystal Microbalance with Dissipation under Flow Conditions

Asphaltenes can cause operational challenges in petroleum production facilities and adversely affect production by adsorption on mineral surfaces and alteration of the oil wettability of reservoirs. Therefore, understanding asphaltene adsorption mechanisms and their effects is crucial to improving the efficiency of oil production and reducing costs. In this study, we focus on understanding the impact of asphaltene concentration and the depositing environment of asphaltene adsorption on solid surfaces using the quartz crystal microbalance with dissipation (QCM-D) technique. The initial and long-term kinetics of adsorption at different concentrations were examined on three different solid surfaces including silicon dioxide to represent quartz mineral, stainless steel, and gold. The frequency-dissipation data showed evidence of monolayer adsorption initially, followed by multilayer formation. At short times, the adsorbed mass increased linearly with time, suggesting that the process was kinetically controlled rather than diffusion-controlled. The results were reproducible and did not depend on convection velocity but did depend on the surface material. At later stages, the monolayer development appeared to follow the random sequential adsorption (RSA) theory. Once multilayer adsorption commenced, the rates agreed well with the two-layer model of Zhu and Gu, 1990. The impact of asphaltene adsorption on the wettability of the surface was examined using contact angle studies, which showed decreasing water wettability with an increase in the adsorbed mass. The contact angle of water after 12 h of adsorption leveled off at around 100° on all three surfaces. Contact angle measurements were also used to evaluate if brine salinity causes the wettability alteration of surfaces with the adsorbed asphaltene. The results indicate that at 3% NaCl solution, the contact angle decreased only slightly by less than 2°.

The Neglected Role of Asphaltene in the Synthesis of Mesophase Pitch

This study investigates the synthesis of mesophase pitch using low-cost fluid catalytic cracking (FCC) slurry and waste fluid asphaltene (WFA) as raw materials through the co-carbonization method. The resulting mesophase pitch product and its formation mechanism were thoroughly analyzed. Various characterization techniques, including polarizing microscopy, softening point measurement, Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), were employed to characterize and analyze the properties and structure of the mesophase pitch. The experimental results demonstrate that the optimal optical texture of the mesophase product is achieved under specific reaction conditions, including a temperature of 420 °C, pressure of 1 MPa, reaction time of 6 h, and the addition of 2% asphaltene. It was observed that a small amount of asphaltene contributes to the formation of mesophase pitch spheres, facilitating the development of the mesophase. However, excessive content of asphaltene may cover the surface of the mesophase spheres, impeding the contact between them and consequently compromising the optical texture of the mesophase pitch product. Furthermore, the inclusion of asphaltene promotes polymerization reactions in the system, leading to an increase in the average molecular weight of the mesophase pitch. Notably, when the amount of asphaltene added is 2%, the mesophase pitch demonstrates the lowest ID/IG value, indicating superior molecular orientation and larger graphite-like microcrystals. Additionally, researchers found that at this asphaltene concentration, the mesophase pitch exhibits the highest degree of order, as evidenced by the maximum diffraction angle (2θ) and stacking height (Lc) values, and the minimum d002 value. Moreover, the addition of asphaltene enhances the yield and aromaticity of the mesophase pitch and significantly improves the thermal stability of the resulting product.