Crude Oil Transportation Research Articles

Effect of Cold Work, Ageing on Hardness and Ultimate Tensile Strength of Microalloyed Steel

Recent past witnessed the widespread use of High Strength Low Alloy steels in several structural applications, including pressure vessels, line-pipe transportation of crude oil in the oil industry and many more. API X-65 grade is widely used as a promising material for line-pipe applications in the oil industry. HSLA X-65 plate steels are produced by normalising, Controlled Rolling (CR), Direct Quenching & Tempering (DQT) or Quenching & Tempering (Q&T) techniques. These steels are characterised by their low carbon concentration while maintaining low alloy additions. Micro alloy additions such as V, Ti, and Nb provide substantial precipitation strengthening effect. Strengthening, hardness and microstructural examinations are conducted in all the stages to ascertain X-65 HSLA steel's ageing behaviour.

(Digital Presentation) Investigation of Microstructure Dependent Inhibitor Adsorption Mechanism on Carbon Steel By in Situ Atomic Force Microscopy

In the petroleum industry, organic surfactant type inhibitors have been widely applied in the oil and gas industry considering their high efficiency. Carbon steels with various carbide contents have also been used extensively as pipeline materials during the transport and storage of crude oil due to their excellent mechanical properties and low cost. The previous investigation of inhibition mechanism on carbon steel is limited by lack of surface characterization techniques at a molecular level. Atomic force microscopy (AFM) can not only provide localized visual observation, but can also achieve the detection of mechanical properties of an inhibitor film. In this study, in situ AFM contact mode friction imaging and in situ AFM tapping mode phase imaging techniques have been applied to investigate the influence of the ferritic-pearlitic microstructure of carbon steel on inhibitor adsorption mechanisms during CO2 corrosion under different inhibitor concentrations. At concentration above surface saturation, AFM contact mode friction images show a large friction contrast between inhibitor covered cementite structures and ferrite structures, while in the absence of inhibitor, this friction contrast almost disappears, indicating the inhibitor adsorption induced this difference. AFM tapping mode phase images indicate uniform adsorption of inhibitor on both cementite and ferrite structures.The differences observed in these AFM analyses indicate that the adhesion force of inhibitor molecules on cementite could be smaller than on ferrite, or the molecular orientations of inhibitor molecules adsorbed on cementite and ferrite structures could be different. The special adsorption behavior of inhibitor molecules on cementite means the carbide component of the microstructure could directly influence inhibitor adsorption and may decrease inhibitor efficiency. Simultaneous linear polarization resistance tests in electrochemical AFM (EC-AFM) cell indicates a maximum inhibition efficiency at concentration above saturation.Keywords : Contact mode AFM, friction contrast, tapping mode AFM, phase contrast, cementite, ferrite, organic inhibitor, adhesion force.Statement of importance:Studies related to inhibitor adsorption mechanisms on ferritc-pearlitic carbon steels can be connected with the practical issues that iron carbide can impair the corrosion inhibitor performance on carbon steels. This AFM work connects the corrosion inhibition effect with the carbon steel components at a molecular level for the first time. Physical explanations regarding the interactions between inhibitor molecules and carbon steel microstructures can also be provided with the assistance of molecular simulations.Figure caption: Contact and tapping mode AFM images of inhibitor film formed on UNS G1018 steel at 2 CMC (100ppm) tetradecyldimethylbenzylammonium inhibitor + 1 wt% NaCl. The contact mode friction image indicates a large friction contrast between inhibitor covered cementite and ferrite structure, while the tapping mode phase image indicates a negligible softness contrast between cementite and ferrite structure. Figure 1

Crude oil wax: A review on formation, experimentation, prediction, and remediation techniques

Wax deposition during crude oil production, transportation, and processing has been a headache since the early days of oil utilization. It may lead to low mobility ratios, blockage of production tubing/pipelines as well as fouling of surface and processing facilities, among others. These snags cause massive financial constraints increasing projects' turnover. Decades of meticulous research have been dedicated to this problem that is worth a review. Thus, this paper reviews the mechanisms, experimentation, thermodynamic and kinetic modeling, prediction, and remediation techniques of wax deposition. An overall assessment suggests that available models are more accurate for single than multi-phase flows while the kind of remediation and deployment depend on the environment and severity level. In severe cases, both chemical and mechanical are synergistically deployed. Moreover, future prospective research areas that require attention are proposed. Generally, this review could be a valuable tool for novice researchers as well as a foundation for further research on this topic.

A study on the dynamic responses of a steel catenary riser transporting varying-density flow and subjected to regular waves

In order to transport crude oil and natural gas from seabed wells to surface floating platforms, the steel catenary risers have been widely used, which are long, flexible and inclined with geometric and structural nonlinearities. These risers are inevitably subjected to waves and vibrate with time. Meanwhile, they may transport oil and natural gas at the same time, in which the total fluid density may change with time and space. In this paper, a nonlinear dynamic model of a steel catenary riser excited by the internal varying-density flow and the external regular waves is theoretically modelled. The present model is numerically solved and validated with the comparisons to experiments and simulation results. The dynamic responses of the riser are analysed and the results demonstrate that when the fluid density inside the riser is fluctuating with a small circular frequency, the vibrations of the riser will be dominated by the internal varying-density flow, however for a large circular frequency, the vibrations of the riser will be dominated by the external regular waves. The dynamic responses of the riser in the region dominated by the external regular waves will be seldom affected by the internal varying-density flow and vice versa.

Research on thermal insulation performance of composite energy storage pipeline with phase change materials

The oil and gas pipeline transportation technology is the key to the surface production of oil field, and the pipeline insulation technology plays an important role in realizing the safe, stable and energy-saving transportation of crude oil. The composite energy storage pipeline with PCM not only has thermal insulation performance, but also can greatly prolong the safe shutdown time when the shutdown condition occurs by taking advantage of the storage and discharge energy characteristics of PCM. In this paper, the reasonable structural parameters of composite energy storage pipeline with PCM were determined by comparing the effective insulation time of three typical pipelines under the same working conditions and combining with thermal resistance method. Considering the nonlinear latent heat release and phase change characteristics of crude oil, a pipe-PCM-oil coupling thermodynamic model was established for the composite insulation pipeline, and numerical solution was carried out. The heat transfer characteristics of composite energy storage pipeline with PCM under different working conditions were analyzed, and the effects of physical properties and structures of different PCM on the thermal insulation performance of composite energy storage pipeline were compared. The research results can provide theoretical support for the safe shutdown scheme of oil pipeline.

Self-crystallization behavior of paraffin and the mechanism study of SiO2 nanoparticles affecting paraffin crystallization

The crystallization behavior of paraffin severely inhibits the extraction and transportation of waxy crude oil. Therefore, in this study, the self-crystallization behavior of paraffin and the mechanism of SiO2 nanoparticles (NPs) affecting paraffin crystallization were investigated microscopically through molecular dynamics (MD) simulations. By analyzing the crystallization morphology and crystallization process of paraffin at different simulated temperatures, we observed the difference in the crystallization of long-chain paraffin molecules and short-chain paraffin molecules from a molecular point of view. Three processes of nucleation, aggregation and crystallization of paraffin crystals were clearly observed. Meanwhile, compared with the light oil system, in waxy heavy oil, a small amount of asphaltene can slightly inhibit the molecular crystallization of paraffin. However, the existence of a large amount of asphaltene changes the structure of paraffin crystals, which makes the paraffin crystals with asphaltene as heterogeneous core intertwined, showing a more complex network aggregation structure. Most importantly, the addition of NPs can significantly improve the diffusion coefficient of paraffin. From the microscopic point of view, the co-crystallization behavior of the grafted carbon chains on the surface of the grafted nanoparticles and the paraffin was observed, which further enhanced the nucleation of the nanoparticles and reduced the crystal size.

Preparation and performance evaluation of oil-tolerant and easy-wetting viscoelastic system for enhancing the stability of highly viscous oil-water lubricated flow

Based on the free sliding phenomenon of the monopterus albus in the cave, an oil-tolerant and easy-wetting viscoelastic system (A3B4C3E5F2) was selected and compounded as a possible lubricant to enable the transportation of heavy crude oil. In the viscoelastic system, the final floating equilibrium velocity of LD1 crude oil droplets with a diameter of about 5 mm is 0.01853 mm/s, and the floating resistance coefficient (C D) is 11067862, which shows favorable oil suspension performance. When the shear rate is approximately zero, the viscosity of the viscoelastic system is about 7000 mPa·s. However, when the shear rate is up to100 1/s, the viscosity is only about 32 mPa·s. A high viscoelastic film is formed at shutdown or low flow rates. Conversely, a low viscosity liquid ring formed at high flow rate. After being wet by easy-wetting viscoelastic system, the contact angle between LD1 crude oil and common pipe materials is wider than 160° at 30 min. The incubation time (t 0) and the wettability composite index (WCI) are shorter than 1800 s and higher than 4800, respectively. Upon stability evaluation, the system can maintain good viscoelasticity and wettability in the range of temperature (5 ∼ 90 °C), oil content (0 ∼ 15 wt.%), and shear rate (0 ∼ 1000 1/s), respectively.

Techno-economic analysis of heating techniques for transportation of heavy crude oils by land pipeline

Three approaches (heat exchangers with steam, heat exchangers with thermal oil, and direct fired heaters) were analyzed for heating pipeline to transport a heavy crude oil (viscosity of 62,745 cSt a 15.6 °C, and 11.78° API gravity). The selected pipeline has a length of 62.7 km and transports 33.12 m3/h (5000 BPD) of heavy crude oil. With the calculated temperature drop (4.39 °C/km) and pressure drop (0.25 kg/cm2/km), five heating and pumping points each 12.53 km were determined to maintain the required temperature and pressure for the transportation of heavy crude oil. For each heating system, mass and energy balance was done to calculate the size of equipment and utilities consumption. Capital expenditures (CAPEX) and operational expenditures (OPEX) were obtained to identify which heating system exhibits the lowest operating costs. The results indicate that the best heating system is with direct fired heaters from both technical and economic points of view (lower number of equipment, easy and flexible operation, commercial experience, and lower consumption of utilities). OPEX and CAPEX for heating system is with direct fired heaters were 0.32 USD/bbl and 0.78 USD/bbl, respectively. This indicates that the price of heavy crude oil should be 1.1 USD/bbl higher than that at the production point. By means of a sensitivity analysis, it was demonstrated that temperature drop is the determining variable that affects the number of heating points. Increasing temperature from 4.39 to 7 °C/km increased the number of heating point from 5 to 8. A 50% increase of OPEX (utilities) resulted the total costs to be 35% higher with respect to the base case for the evaluated heating systems.

Effect of a Coated Wall on Wax–Asphaltene Molecule Diffusion, Aggregation, and Adhesion Mechanism: A Molecular Dynamics Simulation Study

Coating is increasingly used as a cost-effective strategy for controlling heavy component deposition in waxy crude oil transportation flowlines. This paper systematically investigated the micro influence mechanism of the coated wall on the diffusion, aggregation, and adhesion behavior of wax–asphaltene molecules by the molecular dynamics (MD) method. A set of experiments was performed to determine the properties of the waxy crude oil. For overcoming the limitations of the model simplification of previous MD studies, the MD models based on experimental data were developed to characterize the motion behavior of wax–asphaltene molecules on non-coated and coated wall surfaces, and the simulated densities of crude oil components had an error of less than 5% with the National Institute of Standards and Technology (NIST) data, which showed that the established model was accurate and reliable. The simulation results showed that two condensate oil layers were formed on the non-coated wall surface, the diffusion and aggregation behavior of wax–asphaltene molecules were enhanced under the low-temperature condition, and there was considerably heavy component molecules adhesion to the non-coated wall surface. The analysis of mean square displacement, radial distribution function, and relative concentration distribution revealed that 288.15 K was the peak wax precipitation, which was consistent with the experimental conclusion. It was also found that the presence of low surface energy coating weakened the diffusion of heavy component molecules. The epoxy silicone-coated had the weakest interaction with wax–asphaltene molecules. Moreover, the fact that the coated wall had a certain inhibitory effect on the aggregation and adhesion of wax–asphaltene molecules in the pipeline was proven, where the epoxy silicone-coated had the strongest inhibitory effect. These investigations present new insights and guidance for controlling heavy component deposition by coating in the pipeline transportation process of waxy crude oil.

Pressure Drop Prediction of Crude Oil Pipeline Based on PSO-BP Neural Network

Pipeline transportation of crude oil has great advantages over traditional oil transmission methods, in terms of economic and environmental protection. The main costs in the oilfield surface system are the fuel costs for heating the crude oil during transportation and the electricity costs for the pumping units. In the northeast of China, where winter temperatures are extremely low and the oil has a high freezing point and high viscosity, higher temperatures, and pressures are required to transport crude oil. With machine learning widely used in many industries and achieving better results, the digital management of oil pipelines has stored a large amount of production and operation data, which has laid the foundation for the research of oil pipeline process calculation using machine learning methods. In this paper, a crude oil pressure drop calculation of an oil pipeline in Northeast China is carried out based on a neural network. For pipeline pressure drop calculation, the back propagation neural network (BP) pressure drop calculation model and particle swarm optimization for back propagation neuron network (PSO-BP) pressure drop calculation model are established. Two models were used to calculate and compare the measured data, and the average absolute error of the PSO-BP model was the smallest, which was 0.015%. Compared with the BP model, the average relative error is reduced by 13.16%. Therefore, The PSO-BP pressure drop calculation model has high accuracy and is of practical significance for predicting pipeline pressure drop.

Competitive adsorption of asphaltene and n-heptane on quartz surfaces and its effect on crude oil transport through nanopores

• Competitive adsorption mechanism between asphaltene and n-heptane on quartz surfaces was illustrated from molecular perspective. • Influence of asphaltene deposition on the transport of light oil is clarified. • Work of adhesion and adsorption time ratio were proposed to quantify adsorption strength. • Flow behaviors of asphaltene and n-heptane in two quartz nanopores were compared. Asphaltene deposition is a ubiquitous problem in crude oil exploitation, which can cause the blockage of pore throat, leading to a significant reduction of oil recovery. Understanding the microscopic mechanism of asphaltene deposition and its influence on the oil flow in nanopores is critical for effective exploitation of crude oil. In this study, we investigated the competitive adsorption of asphaltene and n-heptane on quartz surfaces using molecular dynamics simulations. We found that asphaltene shows a much stronger adsorption ability on the quartz surfaces than n-heptane, resulting from both interfacial energy strength and the poly-aromatic ring interactions among asphaltene molecules. With the deposition of asphaltene, the flux of n-heptane transport in nanopores is greatly decreased, which can be attributed to the reduction of effective aperture size and the disappearance of possible slip near the surface. The difference in adsorption and flow behaviors between asphaltene and n-heptane can be further elucidated by the comparison in work of adhesion for several interfaces. Besides, the effect of surface hydroxyl groups of quartz substrates was proved to have a prominent impact on the adsorption of asphaltene on the quartz surfaces, leading to a considerable enhancement of oil flux through SiO 2 nanopores. Our work advances the understanding of the low oil recovery caused by asphaltene deposition and has a significant reference value to the effective production and evaluation of crude oil.

Crude oil and the problem of wax deposition on pipeline systems during transportation: A review

Crude oil, the world’s major source of energy, is obtained from the earth as a Newtonian fluid and needs to be transported to refineries for further processing. Pipeline transport has proven to be the most efficient, environmental-friendly and cost effective of all modes of crude oil transportation from subsea production sites. However the formation and deposition of waxes (mainly paraffinic and asphaltenic components) along pipelines remains one of the greatest flow assurance problem in the petroleum industry. This is aided by attainment of wax appearance temperature (WAT), the crude’s hydrocarbon contents and rheological properties, and the production conditions amongst others. The deposited waxes clog the pipeline, reduces the flow diameter, converts the behavior of the fluid from Newtonian to non-Newtonian, decreases throughput, causes more work on pumps and other process equipment, increases energy consumption, and ultimately raises the cost of production thereby decreasing profits. It also leads to several downtimes and in extreme cases can cause permanent shut down of facilities. Several studies have been done to understand the nature of crude oil waxes and the various techniques for solving this problem. This paper takes a critical look at crude oil and reviews the current state of research into the causative factors, deposition mechanisms and remediation methods including the thermal, mechanical, biological and chemical techniques. At the end there is a conclusion and further research on the use of biological techniques (microorganisms) has been advised herein.

Numerical study of gelation and flow restart in a waxy crude oil riser

Precipitation of paraffin wax during crude oil transportation in low ambient temperature presents many technological challenges in petroleum industries. During a complete shutdown, the precipitation intensifies to form a gel-like structure which usually demands high restart pressure during flow restart operation. Numerical simulations are performed to investigate the gelation process in the shutdown pipeline and subsequent non-isothermal flow start-up operation in a heterogeneously gelled pipeline. A Finite volume method is used to solve the mass, momentum and energy conservation-based governing equations over an orthogonal static grid setup. The gelation model utilizes a modified Eyring-based viscosity model to account for temperature-dependent changes in gel strength. On the other hand, the flow restart process follows the deformation and temperature-dependent shear-thinning based rheological model. The pipeline under consideration in the present work is vertical, replicating flow in risers. Our gelation model considers natural convection-driven flow inside the pipeline, which incites the hot oil in the core to mix with cooler fluid at the wall. The gelation is achieved through cooling the static crude oil in the pipeline for different timespans varying from 3 h to 15 h. The gelation stage ends up producing spatial heterogeneity in gel strength. Such heterogeneity leads to weaker gel structure in the core causing early flow restart due to cohesive failure of the gel medium at some interior radial location. Hence, it can be concluded that depending on the cooling stage, the heterogeneous gel with a weaker gel in the pipe core can restart faster than when the pipeline is filled with the gel having an equivalent average temperature. The findings provide realistic insights into the mechanism of gel failure in the pipeline, and the knowledge can be utilized to develop a better flow assurance strategy.

An insight into molecular weight distributions of asphaltene and asphalt using Gel Permeation Chromatography

Asphaltene and asphalte precipitations during production, transportation and processing of crude oil are one of the problems in the oil industry. The amount and characteristics of these precipitations depend on the type of solvent, oil–solvent ratio, time, pressure, temperature, etc. Measuring molecular weight distributions of asphaltene and asphalt could be necessary to predict the phase behavior and prevent asphaltene and asphalte depositions. Therefore, in this study, the molecular weight distributions of asphaltene and asphalt were studied. For this purpose, asphaltene and asphalt samples were prepared by adding different ratios of precipitants such as n-pentane, n-hexane, and n-heptane in an Iranian crude oil using the IP-143 method. Then, we used Gel Permeation Chromatography to measure the molecular weight distributions of these samples. The obtained results indicate that asphaltene has more aggregation with higher molecular weight compared to asphalt. In addition, results show that the molecular weight distribution of asphaltene is generally wider than the molecular weight distribution of asphalt.

Emulsifying stability and viscosity reduction for heavy crude oil in surfactant-polymer composite system

Heavy crude oil is one of the most precious and complex molecular mixtures available, with considerable economic relevance. Nevertheless, its high viscosity and complicated chemical compositions pose an exceptional challenge for viscosity reduction with a compound emulsification system in heavy oil exploitation. Here, two types of polymers were synthesized and compounded with surfactant SDS to reduce the heavy crude oil viscosity. Their emulsifying properties in demineralized water and mineralized water were measured to evaluate their differences from macroscopic views. Furthermore, the corresponding emulsion system (involving resins, asphaltenes, surfactants, polymers, etc.) was also simulated and computed using molecular dynamics simulation to investigate the relationships of various compositions on emulsifying properties at the molecular scale. The results showed that the surfactant-polymer composite system formed by the amphiphilic polymer had an obvious advantage in emulsifying stability with the water segregation rate of 60.6% after 48 h in the simulated salinity and the viscosity reduction rate reached more than 92.1% after optimization. Besides, the electrostatic interaction is the major part of the potential energy in emulsion systems at a ratio of 87.8%. The divalent cations (Ca2+ and Mg2+) resulted in the shrinkage or collapse of molecular conformation of the water-soluble polymer by 19%. The variation of interaction energy in salt solutions for different emulsifying systems caused a series of experimental and simulated distinctions, such as solution viscosity, interface behaviors, the number of hydrogen bonds, and the spatial distribution function, which ultimately determined the emulsifying properties of heavy crude oil. Notably, this work offers insight into the interactions and influences of complex mixtures in oil–water systems. It also facilitates to design and apply the innovative functional chemical additives in heavy crude oil extraction and transportation.

Perspectives on Microfluidics for the Study of Asphaltenes in Upstream Hydrocarbon Production: A Minireview

The utilization of microfluidics has generated deep insights into asphaltene precipitation mechanisms and oil–water emulsion stabilization. Agglomeration and precipitation of asphaltenes can cause flow assurance problems during the extraction and transportation of crude oil. Change in temperature, pressure, reservoir conditions, and solvents can change the local environment, leading to asphaltene precipitation. Understanding asphaltene properties and precipitation pathways becomes critical in devising mitigation methods, demulsifiers, and suitable conditions during hydrocarbon processing. Microfluidics has helped in high throughput measurement studies, understanding critical processing conditions, fast demulsifier screening, and the effect of solvent concentration on deposition, generating useful information for utilization at the point of resource extraction facilitating improved resource management. It has become possible to capture the porous, complex nature of reservoir formations and the interaction of chemicals during precipitation through integrated analytics and visualization studies available only through microfluidics. The use of droplet microfluidics, with optical microscopy and high-speed imaging to study the oil–water interface, has resulted in greater understanding of the role of asphaltenes in interfacial properties and emulsion stabilization. This minireview highlights the crucial aspects of microfluidics that have been used to understand physicochemical behavior and dynamics of asphaltene deposition. Some of the unique devices have been presented focusing on the key elements of microfluidics design, fabrication, and analysis, as the insight obtained from microfluidics strongly depends on the device design and the controllability of the experimental parameters. Successful implementation of microfluidics for efficient and controlled experiments, short analysis time scales and rapid screening, and generation of high-quality, reliable data that convey asphaltene deposition issues and interface behavior in emulsions shows the importance of microsystems for advancing knowledge in hydrocarbon production and processing.

Quantitative analysis of retained austenite in Nb added Fe-based alloy

The use of Pipelines for long-distance transportation of crude oil, natural gas and similar applications is increasing and has pivotal importance in recent times. High specific strength plays a crucial role in improving transport efficiency through increased pressure and improved laying efficiency through reduced diameter and weight of line pipes. TRIP-based high-strength and high-ductility alloys comprise a mixture of ferrite, bainite, and retained austenite that provide excellent mechanical properties such as dimensional stability, fatigue strength, and impact toughness. This study performs microstructure analysis using both Nital etching and LePera etching methods. At the time of Nital etching, it is difficult to distinctly observe second phase. However, using LePera etching conditions it is possible to distinctly measure the M/A phase and ferrite matrix. The fraction measurement was done using OM and SEM images which give similar results for the average volume fraction of the phases. Although it is possible to distinguish the M/A phase from the SEM image of the sample subjected to LePera etching. However, using Nital etching is nearly impossible. Nital etching is good at specific phase analysis than LePera etching when using SEM images.

Phase change composites with thermal‐formability and photothermal storage property for high flux crude oil transmission

AbstractCrude oil pipeline transportation is one of widely used ways in land transportation and comprises a large share of the world's long‐distance oil transmission. Warming and heat preservation of crude oil is vital for efficient oil pipeline transportation. However, it remains a formidable challenge in coping with caused tremendous energy consumption and environmental pollution. In this work, bio‐based phase change composites with superior thermal‐formability and photothermal storage properties were fabricated and molded to photothermal oil transportation system using template‐confined thermoforming strategy. On the basis of desirable thermal energy management ability of PEG as well as the synergistic effects between heat localization and electron nonradiative transition of Fe2O3 nanoparticles, the system realized a remarkable decrease in oil viscosity and efficient transmission. Particularly, the preparation process could be facilely scaled up and indicate real application feasibility. This successful exploration offers a significant path for developing green, highly effective crude oil transportation.

Asphaltene aggregation and deposition in pipeline: Insight from multiscale simulation

Understanding the colloidal structure of crude oil in pipeline is of great significance for finding effective solutions to remediate and prevent the aggregation and deposition of asphaltene during transport process. Here, combing large-scale structural-unit-based dissipative particle dynamics simulations and all-atom molecular dynamics simulations, the colloidal structure and interatomic interactions of crude oil in the pipeline are studied. The analysis of structural characteristics of asphaltene aggregates demonstrates that temperature, pressure, and flow speed jointly affect the colloidal structure of crude oil at mesoscopic level and the compactness of asphaltene aggregates at microcosmic level. By analyzing the mesoscopic structural properties of crude oil during transport and the microscopic interaction between crude oil and Fe2O3, the competitive adsorption of crude oil components on pipeline surface is demonstrated. We reveal that although the fluid movement of crude oil is favorable for structural transformation of asphaltene aggregate from large size to small size in bulk phase, but the asphaltenes are steadily deposited onto pipeline surface with the exfoliation of other oil components. These findings provide a molecular-level understanding of the colloidal structure of asphaltene during transport of crude oil through pipeline.

Recent advancements in hydrocarbon bioremediation and future challenges: a review.

Petrochemicals are important hydrocarbons, which are one of the major concerns when accidently escaped into the environment. On one hand, these cause soil and fresh water pollution on land due to their seepage and leakage from automobile and petrochemical industries. On the other hand, oil spills occur during the transport of crude oil or refined petroleum products in the oceans around the world.These hydrocarbon and petrochemical spills have not only posed a hazard to the environment and marine life, but also linked to numerous ailments like cancers and neural disorders. Therefore, it is very important to remove or degrade these pollutants before their hazardous effects deteriorate the environment. There are varieties of mechanical and chemical methods for removing hydrocarbons from polluted areas, but they are all ineffective and expensive. Bioremediation techniques provide an economical and eco-friendly mechanism for removing petrochemical and hydrocarbon residues from the affected sites. Bioremediation refers to the complete mineralization or transformation of complex organic pollutants into the simplest compounds by biological agents such as bacteria, fungi, etc. Many indigenous microbes present in nature are capable of detoxification of various hydrocarbons and their contaminants. This review presents an updated overview of recent advancements in various technologies used in the degradation and bioremediation of petroleum hydrocarbons, providing useful insights to manage such problems in an eco-friendly manner.