Oil Transportation Research Articles

Finite element analysis of the stress and buckling behaviour of cylindrical oil tank under internal pressure

Finite element analysis of the stress and buckling behaviour of cylindrical oil tank under internal pressure

Updating the residual strength – damage index diagrams for hull girder collapse predictions of grounded ships

ABSTRACT A decade ago, the authors introduced the concept of residual strength-damage index diagrams to facilitate rapid predictions of buckling collapse in damaged structures. They demonstrated this approach with an example focused on predicting the collapse of hull girders. [Paik JK, Kim DK, Park DH, Kim HB, Kim MS. 2012b. A New Method for Assessing the Safety of Ships Damaged by Grounding. Int J Marit Eng. 154:A1–A20.]. This paper is a sequel to the 2012 paper by updating the grounding damage data used for the diagrams with more ships in types and sizes, where a total of 12 ships for three different types with four sizes per type are considered: oil tankers (Panamax, Aframax, Suezmax and VLCC), bulk carriers (Handysize, Supramax, Kamsarmax, Capesize), and container ships (3,500TEU, 5,000TEU, 7,500TEU and 13,000TEU). Literature reviews are also made to gain insights on the hull girder collapse of grounded ships, which can be implemented into the updated diagrams. It is confirmed that the proposed methodology can be useful in predicting the hull girder collapse of grounded ships at an earlier stage so that the best timely rescue schemes can be developed to prevent unwanted consequences after grounding, such as casualties, sinking and marine pollution.

The effect of subcooling on hydrate generation and solid deposition with two-phase flow of pure water and natural gases

Deepwater oil and gas transportation systems play a crucial role in energy supply, but also face the challenges of hydrate generation and blockage. The study observed hydrate generation and deposition at different subcooling degrees and flow rates by using a high-pressure fully visualized recirculation pipeline. It was found that the subcooling degree has a nonlinear positive correlation with the total amount of hydrate generated. The hydrate formation at 11.7 °C subcooling was 4.5 times higher than that at 9 °C subcooling. According to the hydrate conversion rate analysis, the hydrate growth process under low subcooling conditions directly transitions from the bubble-promoting zone to the termination point of hydrate generation. Combined with the deposition state of the pipe wall and the differential pressure change curves, the risk of blockage at different subcooling levels and flow rates can be assessed.

Endocytosis-Inspired Zwitterionic Gel Tape for High-Efficient and Sustainable Underoil Adhesion.

Marine oil exploration is important yet greatly increases the risk of oil leakage, which will result in severe environment pollution and economic losses. It is an urgent need to develop effective underoil adhesives. However, realizing underoil adhesion is even harder than those underwater, due to the stubborn attachment of a highly viscous oil layer on target surface. Here, inspired by endocytosis, a tough gel tape composed of zwitterionic polymer network and zwitterionic surfactants is developed. The amphiphilic surfactants can form micelle to capture the oil droplets and transport them from the interface to gel via electrostatic attraction of polymer backbone, mimicking the endocytosis and achieving robust underoil adhesion. Benefiting from the oil-resistance of polymer backbone, the gel further realizes a combination of i) long-term adhesion with high durability, ii) repeated adhesion in oil, and iii) renewable adhesion efficiency after exhausted use. The tape exhibits an ultra-high adhesive toughness of 2446.86 J m-2 to stainless steel in silicone oil after 30 days' oil-exposure; such value of adhesive toughness surpasses many of those achieved in underwater adhesion and is greater than underoil adhesion performance of commercial tape. The strategy illustrated here will motivate the design of sustainable and efficient adhesives for wet environments.

Numerical Investigation of Oblique Currents’ Effects on the Hydrodynamic Characteristics of Ships in Restricted Waters

The influence of oblique currents in narrow and shallow channels causes the fluid flow around ships to become complex. To analyze the hydrodynamic characteristics of a ship in such channels, it is essential to examine the influence of oblique currents on the ship’s hydrodynamic characteristics. In this study, current direction, ship speed, current speed, and water depth were identified as determinants affecting the hydrodynamic characteristics of a ship. Numerical simulations were conducted on a large oil tanker to investigate the effects of these factors on the ship’s hydrodynamic characteristics. The viscous fluid flow was modeled using the unsteady Reynolds-averaged Navier–Stokes (URANS) equations in conjunction with the k-ε turbulence model. The URANS equations were discretized using the finite volume method. The numerical results indicate substantial differences in the hydrodynamic characteristics of ships under oblique current conditions compared to still-water conditions. At a current direction of β = −45°, the direction of the sway force is consistent with that of still water’s sway force, which is an attractive force. The yaw moment at β = −45° changes from a bow-out moment under still-water conditions to a bow-in moment. Conversely, at a current direction of β = 45°, the sway force shifts from an attractive force under still-water conditions to a repulsive force. The yaw moment acts as a bow-out moment, which is consistent with that observed in still-water conditions. Furthermore, the influence of hydrodynamic characteristics on a ship varies significantly with changes in ship speed, current speed, and water depth. To ensure the safe navigation of ships, it is essential to develop and apply comprehensive strategies and countermeasures that account for practical conditions.

Study on rapid policy-based strategic environmental assessment-taking China's regional development policy of Zhejiang Pilot Free Trade Zone as an example

Strategic Environmental Assessment(SEA) is acknowledged to be an important decision support tool. SEA concerns potential environmental impacts of decisions made by policy, plan and programs. At present, policy-based SEA is still in the exploratory stage in China. The development of policy-based SEA is extremely slow due to institutional and technical difficulties. In practice, the time from policy proposals to policy implementation is relatively short. So the corresponding policy-based SEA should reflect the characteristics of rapidity, centre on the seriously negative impact that may be caused policy implementation, and provide early and initial warnings.A simple and rapid framework was designed for policy-based SEA in this study. The framework includes four parts, namely, policy analysis, eco-environmental impact identification, eco-environmental sensitivity assessment, policy recommendations. Following this framework, regional development policy of Zhejiang Pilot Free Trade Zone (FTZ) was assessed. Results reveal that: 1)seriously negative environment impacts may arise from petroleum refining and chemical industry, oil and gas storage and transportation, iron ore transportation, liquid bulk commodities transportation. 2) Central Daishan area, Shengsi archipelago, Taohua Island, Liuheng island in Zhejiang FTZ is relatively of high eco-sensitivity, thus the fore-mentioned activities should be environmentally friendly or restricted in these areas. 3)In the future, continuous efforts should be made to promote sealing and automation of petroleum refining, chemical industry. Green petrochemical manufacturing technology utilization is recommended to reduce pollution from the source. Further, accelerating the construction of transportation pipelines is suggested in order to reduce air pollutants emissions caused by vehicle transportation activities. Fishery stock enhancement and releasing is recommended to counteract negative impact on fishery caused by iron and liquid bulk commodity marine transportation.

Insights into the Global Characteristics of Shipping Exhaust Emissions at Berth

The need for an accurate inventory of ship emissions is vital for atmospheric scientists assessing the environmental impact of shipping and for policymakers aiming to regulate and incentivize emission reduction. This study used data from 189 international ports, related to ship arrivals and departures, to develop emissions inventories. Emission characteristics were examined in detail, classifying emissions by factors like ship type, month, and region. The analysis identified oil tankers and container ships as main emitters among ship categories. A detailed analysis of the monthly distribution of emissions from vessels at berth worldwide was conducted based on precise arrival and departure times. Singapore, Rotterdam, and Antwerp were the ports with the highest emissions from ships at berth. Overall, this study presents the spatial and temporal emission characteristics of ships at berth in 3912 ports around the world, which can support the development of emission reduction strategies in port management.

Wax Deposition of Diesel Oil and Consequent Contamination of Gasoline in Sequential Transportation of Product Oil Pipeline

Wax deposition of diesel oil and contamination of gasoline by diesel wax deposit is a severe problem in sequential transportation of product oil in pipes. However, it has long been neglected by the pipeline transportation industry. In response, this work aims to present a unique perspective on wax deposition of diesel oil and consequent contamination of gasoline. A cold finger apparatus was designed and constructed. Model oil composed of diesel and refined wax was prepared for wax deposition. Shear dispersion was excluded for wax deposition of diesel oil. Moreover, dissolution experiments of diesel wax deposit in gasoline were conducted. It was found that the dissolution rate increases with oil temperature and decreases with cold finger temperature and shear stress. Analysis on gasoline quality after diesel wax deposit dissolution indicated that contamination of gasoline caused by diesel wax deposit severely deteriorates its distillation range, but the octane number remains acceptable. This work features an interesting investigation on the wax-deposition mechanism of diesel oil, dissolution characteristics of diesel wax deposit, as well as quality deterioration of subsequent gasoline. It would be helpful in scheduling a product oil-transportation program.

Flow assurance of waxy crude oil through thermal methods using nichrome wire and ultrasonic waves effects – Experimental investigation

When crude oil transportation stops for a certain period, the low temperature causes sufficient wax crystallization inside pipelines. During the crystallization, pipelines are exposed to a decrease in the inner diameter of the pipe, which leads to clogging and an increase in pressure drop. The higher pressure drop may require a huge pumping force to break the wax crystals and start the flow, increasing the level of risks and costs. Recently, many thermal and non-thermal methods have been used to alleviate wax deposition, such as surfactants, electric heating, and chemicals. In this study, flow assurance of heavy crude oil was investigated through pipelines using ultrasonic waves, nichrome wires, and combined methods. It includes conducting an experimental investigation on the ability of applying the ultrasonic effect and nichrome wires to improve the transportation performances of waxy crude oil through pipelines in a safe and environmentally friendly manner at the lowest costs while maintaining the characteristics of crude oil at high levels. The cooling rate was also studied at surrounding temperatures close to 30°C, 15°C, and 5°C. An experimental setup was developed to study the efficiency of the combined method in heating the pipeline. It was observed that the combined method was found effective in heating pipelines to higher temperatures in a shorter time. When the surrounding temperature was 30 °C, the combined method was able to raise the temperature of the crude oil to 80 °C in just 9.96 min, while the nichrome wires took 25 min to raise the temperature to 73 °C. As for the ultrasonic, it took 28 min to bring the temperature to 65.6 °C. It has also been proven that the highest cooling rate occurs at the walls of the pipeline. Therefore, the deposition of wax begins on the walls first and then moves successively to the middle.

Modification of Nanyang crude oil by a functional magnetically responsive flow modifier in synergy with magnetic field

Abstract Nanyang crude oil is classified as high wax crude oil. It has severe wax deposition and poor low-temperature fluidity, which pose a major risk to the safety of pipeline transportation of wax-containing crude oil. A large-size polymer-coated magnetic nanosphere was created by dispersion polymerization employing methyl methacrylate, nano-iron oxide, tetraethoxysilane, and dodecyltriethoxysilane as raw materials to address the aforementioned issues.Ethylene-vinyl acetate copolymer was compounded to provide a useful magnetic response flow modifier.Using FTIR and ESEM, the polymer grafted on the iron oxide nanosphere’s surface was shown. After evaluating the functional magnetic response flow modifier’s impact on the yield stress and viscosity of a Nanyang crude oil, the effect of the magnetic field was introduced to analyze the functional magnetic response flow modifier’s synergistic effect on viscosity and yield stress. The results show that the functional magnetic response flow modifier may greatly lower yield stress and viscosity when compared to the EVA pour point depressant. Additionally, applying an alternating magnetic field could amplify the functional magnetic response flow modifier’s beneficial effects on Nanyang crude oil.

Study of a multifunctional composition in the preparation and transportation of heavy oils

Study of a multifunctional composition in the preparation and transportation of heavy oils

The development of high-performance kinetic hydrate inhibitors by introducing N-vinyl caprolactam and vinyl ether homopolymers into PVCap

Low dosage kinetic hydrate inhibitors (KHIs) are a kind of alternative chemical additives to prevent gas hydrate formation in oil & gas production wells and transportation pipelines. In this work, a series of KHIs were experimentally synthesized with N-vinyl caprolactam (N-VCap) and vinyl ether including vinyl ether, vinyl n-butyl ether, vinyl isobutyl ether, triethylene glycol divinyl ether, with the mole ratio ranging from 9:1 to 5:5. The inhibition performance of new-synthesized KHIs on the formation process of methane hydrate were examined and compared with that of commercial N-vinyl caprolactam PVCap. Several ethylenediamine reagents were used as synergists and tested to improve the inhibition capacity of new-synthesized KHIs. The experimental results demonstrate that the introduction of ether groups on PVCap improves the performance of hydrate inhibitors. PVCap-VNBE (N-VCap: vinyl n-butyl ether = 5:5) showed the best inhibition performance for methane hydrate, which could extend the TVO to 1251 min under 6 K subcooling. N,N'-dimethylethylenediamine shows the best synergistic effect for PVCap-VNBE (5:5), and extends the TVO by 2.75 times at 7 K subcooling. Additionally, the relationship between hydrate inhibition performance and interfacial tension of newly-synthesized KHIs under high pressure were studied. It shows that the lower interfacial tension of KHIs would result in longer onset time, exhibiting better inhibition performance.

Research risks in operation of oil - chemical tanker fleets: A review of the studies

Operation and management of oil - chemical tanker fleet will face many difficulties if businesses are not aware of the importance of risk management. Therefore, risk research is an urgent issue for maritime transport companies in general and for oil and chemical cargo transportation in particular. This paper summarizes the research in the operation of oild – chemical tanker fleet by means of comprehensive methods and analysis of the document. The purpose of the paper is to identify, evaluate risks and propose solutions to respond to risks in this field. The article also discusses the strengths of previous studies and specifies the research gap. The group of authors analyzed 91 representative articles from 2000 to 2024 to present a picture of the research situation on risks in the operation of oil-chemical tanker fleets worldwide. The results of the paper revealed research gaps identified by the group through the process of analyzing, evaluating, and identifying risk categories, which serve as the foundation for future studies.

Flow corrosion simulation study of local defects in CO2 saturated solution

The inner walls of oil and gas transportation pipelines are prone to the formation of localized pitting defects due to the presence of solid particles in multiphase flow. The continuous flow poses a risk of perforation leakage in the pipe wall. To investigate the development of defects under flow corrosion and assess the impact of flow, a multi-field coupling finite element model incorporating fluid dynamics, reactions, and mass transfer was developed. The flow corrosion of local defects with various depths in a CO2-saturated solution was simulated. The calculation of mass transfer in corrosion is coupled with the precise flow field solved by large eddy simulation (LES) method. It has been observed that the distribution of corrosive substances is significantly affected by the flow due to local defects. Within these defects, the maximum concentration of corrosion product Fe2+ is observed on the upstream surface of defects. While the H+ accumulates at the downstream wall, which affects the corrosion rate. The local turbulent state is influenced by the depth of defects, and the interplay of the turbulence intensity with reflux velocity determines the mass transfer.

Screening oil tank bottom sludge microbial community for identification of native efficient hydrocarbon-degrading bacteria for bioremediation purposes

Screening oil tank bottom sludge microbial community for identification of native efficient hydrocarbon-degrading bacteria for bioremediation purposes

Research on marine oil spill identification based on laser-induced fluorescence LiDAR

The rise in oil extraction and transportation in marine environments has led to frequent oil spill incidents, posing a severe threat to marine ecosystems and becoming an urgent environmental issue. This paper presents a laser-induced fluorescence light detection and ranging (LiDAR) system specifically designed for monitoring marine oil spills. The system comprises a laser emission module, a receiving module, a data processing module, and a wireless transmission module. Through outdoor experiments, the system has demonstrated its effectiveness and reliability in detecting and identifying various oil types, including crude oil, diesel, heavy oil, gasoline, and lubricating oil. Additionally, a BP neural network model was employed to process the fluorescence spectral data collected by the LiDAR system. This model successfully predicted oil types with an accuracy of 96.58%. This research presents a new technological solution for marine oil spill monitoring, offering significant potential for practical applications and further research.

Lab-based scale measurements of internal storage of crude oil tank based on non-contact infrared thermography technique

Non-contact sludge measurement methods for storage tanks can address the challenge of measuring the volume of sedimented sludge during long-term storage. While infrared thermography technology can address the issue of liquid level detection, its measurement accuracy for the undulating interface of sludge is insufficient. This study designed and constructed experimental setups for measuring sludge in storage tanks. In this study, infrared images taken by an infrared camera were used to record the temperature distribution of the outer wall of the storage tank. The threshold segmentation method is used to determine the accurate sludge boundary line in image processing. Finally, the Three-Dimensional Tank Residue Recovery Algorithm (3D-TRRA) was applied to fit the 3D distribution of the sludge and calculate accurate sludge volumes. The results indicate that the best segmentation is achieved with a threshold of 170. The measurement error for sludge volume is less than 5%. Accurate visual positioning and recognition of sludge are achieved.

Building a model of heating an oil tank under the thermal influence of a spill fire

The object of this study is the process of liquid combustion in a spill, and the subject of research is the distribution of temperature along the wall and roof of a vertical steel tank that is heated under the thermal influence of a spill fire. The heat balance equation for the wall and roof of the tank with oil product was constructed. The assumption of a small thickness of the wall and roof of the tank relative to its linear dimensions makes it possible to move to two-dimensional differential equations of the parabolic type. The equations take into account the radiative heat exchange with the flame, the environment, the internal space of the tank, as well as the convective heat exchange with the surrounding air, the vapor-air mixture, and the liquid inside the tank. Using the methods of similarity theory, estimates of the coefficients of convection heat exchange of the outer surface of the tank with the surrounding air and the inner surface with the vapor-air mixture and liquid in the tank in the conditions of free convection were constructed. The application of the finite difference method for solving the heat balance equations has made it possible to derive the temperature distribution on the surface of the tank at an arbitrary moment in time. It is shown that the value of the coefficient of convection heat exchange of the liquid exceeds the corresponding value for the air-vapor mixture by (1÷2) orders of magnitude. As a result, the part of the wall located below the oil product level is heated to a temperature of (80÷230) °C depending on the viscosity of the liquid. This occurs despite the fact that the value of the mutual radiation coefficient reaches its maximum value at the lower part of the wall. From a practical point of view, this means that the part of the wall above the level of the oil product in the tank can reach dangerous temperature values, and it should be cooled first. The constructed model of tank heating also enables determining the limit time for the start of cooling of the tank.

Numerical Study on the Influence of Various Design Variables on the Behavior Characteristics of Oil and Gas in Internal Floating Roof Tanks

Numerical Study on the Influence of Various Design Variables on the Behavior Characteristics of Oil and Gas in Internal Floating Roof Tanks

Understanding the thermodynamic effects of chemically reactive working fluids in the Stirling heat pump

Within the realm of sustainable heating technologies, this study examines the performance of a Stirling heat pump employing chemically reactive working fluids in contrast to conventional inert counterparts. Reactive working fluids are energy vectors that enable the conversion of not only thermal but also chemical energy within the heat pump. The investigation spans a wide range of theoretical reactive gaseous mixtures, leveraging the ideal gas mixture thermodynamic model. Each fluid is characterized by an equilibrated chemical reaction, denoted as A2(g)⇄2A(g), and distinguished by a set of reaction coordinates: the standard entropy change of reaction and standard enthalpy change of reaction. The chemical reaction evolution and thermodynamic properties are observed in each transformation, and the overall coefficient of performance (COP) of the system is evaluated and benchmarked against that of comparable inert working fluids. It is observed that the exothermic reaction during isothermal compression significantly increases the thermal energy supplied to the heat sink, as well as the thermal energy density per unit maximum volume, by up to 269 %, compared to an inert gas system. However, for the majority of reactive fluids studied, chemical reactions introduce irreversibility in the internal regenerator due to heat transfer across a finite temperature difference, contrary to the case of inert working fluids, penalizing the COP. Consequently, a reduction of up to 28 % in the COP is observed. Nevertheless, there exists a range of reactive fluids, characterized by reversible heat exchange in the internal regenerator, offering increased thermal energy transfer to the heat sink without compromising the COP.