Subsea Oil Pipelines Research Articles

A Magneto-Electric Device for Fluid Pipelines with Vibration Damping and Vibration Energy Harvesting.

This study introduces an innovative energy harvesting system designed for industrial applications such as fluid pipelines, air conditioning ducts, sewer systems, and subsea oil pipelines. The system integrates magneto-electric flow coupling and utilizes a dynamic vibration absorber (DVA) to mitigate the vibrations induced by fluid flow while simultaneously harvesting energy through magnetic dipole-dipole interactions in a vibration energy harvester (VEH). The theoretical models, based on Hamilton's Principle and the Biot-Savart Law, were validated through comprehensive experiments. The results indicate the superior performance of the small-magnet system over the large-magnet system in both damping and power generation. The study analyzed the frequency response and energy conversion efficiency across different parameters, including the DVA mass, spring constant, and placement location. The experimental findings demonstrated significant vibration reduction and increased voltage output, validating the theoretical model. This research offers new avenues for energy harvesting systems in pipeline infrastructures, potentially enhancing energy efficiency and structural integrity.

Vibration Characteristics and Structural Optimization of Pipeline Intelligent Plugging Robot under Turbulent Flow Field Excitation

Pipeline maintenance technology based on pipeline intelligent plugging robot (PIPR) has become an effective method for failure accident prevention of high-pressure subsea oil and gas pipelines. However, during the plugging operation, the vortexes and pressure fluctuation are presented under turbulent flow field excitation, which may lead to vortex-induced vibration and failure of the plugging operation. Therefore, in order to ensure the reliability of pipeline plugging, the vibration characteristics are analyzed using numerical simulation, providing guidance on the structural optimization of PIPR’s end face. Firstly, the flow field characteristics under different PIPR’s end faces are investigated. Secondly, an experimental scheme is designed based on Latin Hypercube Sampling Design (LHSD) optimized by greedy strategy. A mathematical model of the end face’s parameters and pressure gradient is established using a back propagation (BP) neural network. Then, an improved whale optimization algorithm (IWOA) is proposed to optimize the end face’s parameters to minimize the pressure gradient of the flow field. Finally, the experimental study is performed to observe the turbulent flow field and pressure fluctuation to validate the optimization results. The results demonstrate that the PIPR’s end face has a great influence on the vortex-induced vibration response. After structural optimization, the average pressure gradient of the optimal PIPR’s end face has decreased by 84.69% and 54.55% before and after the plugging process, compared to the original end face. This study can provide a reference for pipeline plugging operations, which is significant for preventing pipeline failure accidents.

Path Planning Techniques for Underwater Robots Based on Obstacles in Subsea Oil Pipelines

With the continuous growth of global energy demand, the safety and maintenance of underwater oil pipelines have become a focal point of international concern. Autonomous Underwater Vehicles (AUVs) are increasingly pivotal in inspection, maintenance, and repair of oil pipelines. This paper explores path planning techniques for underwater robots based on obstacles in subsea oil pipelines to enhance operational efficiency and safety. Employing theoretical analysis and simulation, the study systematically addresses key issues in path planning, including environmental modeling, obstacle recognition, path generation, and optimization. By constructing complex underwater environment models and integrating advanced algorithms such as improved ant colony optimization, genetic algorithms, and particle swarm optimization, the research investigates path planning strategies for AUVs under various obstacle distributions. The results demonstrate that the proposed path planning techniques effectively handle obstacles in subsea oil pipelines, significantly improving planning efficiency and robustness. Additionally, the feasibility of multi-robot collaborative path planning is discussed, providing theoretical support for future advancements in underwater robotics. Overall, this study offers new technological insights for the maintenance of underwater oil pipelines and is crucial for enhancing the intelligence level of underwater operations.

Acoustic scattering characteristics of underwater buried oil pipeline

With the development of offshore oil resources, subsea oil pipelines have emerged. As a fast, economical, and safe way to transport oil resources, subsea pipelines are known as the “lifeline” of offshore oil projects. However, the detection of submarine pipelines is very difficult due to the complex underwater environment. One of the mainstream methods to detect submarine pipelines is the employment of sonar. Hence, the acoustic scattering characteristics of submarine pipelines play an important role in detecting themselves. In this study, the acoustic scattering model of the buried pipeline is established using the finite element method, and the scattering mechanism of the buried pipeline is analyzed. The effects of different frequencies, grazing angles, burial depth, and other factors on the acoustic scattering characteristics of the buried pipeline are investigated, providing the reference significance for detecting submarine pipelines.

Investigation on mechanical behaviour of underwater launching process of bidirectional pigging robot in the subsea oil pipeline using Coupled Eulerian-Lagrangian method

Underwater launchers are typically employed for the deployment of pigging robots in subsea pipelines for the purposes of cleaning and inspection. Throughout the launching process, challenges related to vibration, damage, and other issues must be addressed and resolved. In this study, the launching process of the pigging robot is numerically simulated using Abaqus 2020. Utilising the Coupled Eulerian-Lagrangian (CEL) method, the Fluid-Structure-Interaction (FSI) model of the launching process was constructed. And the variation of parameters such as velocity, friction force and tilt angle at different inlet flow rates were analysed. The findings indicate a positive correlation between the average velocity of the pigging robot and the inlet flow rate. The factors such as friction, tilt angle, and offset distance are related to the motion process of the pigging robot. Furthermore, during the pigging robot’s traversal through narrow pipe sections, the sealing discs undergo irregular deformation, generating a reaction force on the robot and inducing vibration. In conclusion, the analysis of the impact of inlet flow velocity on the motion behaviour of the pigging robot offers a theoretical foundation and reference for the successful launch of the robot.

Model analysis of flow-induced vibration (LIV) in submarine oil and gas pipeline

Abstract In order to realistically simulate the flow-induced vibration of submarine oil and gas pipelines, this paper assembles a gas-liquid two-phase flow vibration device, develops a detailed and comprehensive experimental procedure, and sets the flow aperture, flow pressure, flow depth, flow direction, and gas-liquid phase apparent flow rate and other variables. According to the different types of pipelines, the multiphase flow-induced vibration of submarine oil and gas pipelines can be categorized into straight pipe vibration and elbow pipe vibration, and combined with the theoretical knowledge of fluid dynamics and the equations of motion to construct a multiphase flow-induced vibration model of submarine oil and gas pipelines and discuss the vibration mechanism of submarine oil and gas pipelines in two-phase liquid flow. Combined with the corresponding experimental parameters, the vibration phenomenon induced by gas-liquid two-phase flow in submarine oil and gas pipelines is experimentally analyzed. It is analyzed that the first-order intrinsic frequency of the submarine oil and gas pipeline is kept at 23.2 Hz when the value of the Reynolds number of the in-pipe flow ranges from 2.53 × 104 to 1.08 × 107. The first-order intrinsic frequency of the submarine oil and gas pipeline monotonically decreases with the increase of the Reynolds number of the in-pipe flow. In addition, when Ul=0.4m/s, the average standard deviation of the data is only 1.114m/s² with the rise of Ug, indicating that the vibration intensity of the fluid on the subsea oil and gas pipeline increases gradually with the increase of the apparent flow velocity of the liquid phase. By analyzing the multiphase flow problem of oil and gas pipelines, this study is of great significance in improving the efficiency of oil and gas transportation.

Experimental research on vortex-induced vibration suppression of pipeline intelligent plugging operation

Pipeline maintenance technology based on smart isolation device (SID) is an important method to prevent failure accidents for subsea oil and gas pipelines. However, during the plugging operation, vortex-induced vibration may occur due to the complex changes of flow field, which can affect the plugging stability. To ensure the safety of plugging operation, it is necessary to reduce the vortex-induced vibration caused by pipeline plugging. In this paper, an experimental investigation on vortex-induced vibration suppression for subsea pipeline plugging operation is conducted from three aspects. The shape of end face, plugging velocity and spoiler device are investigated to suppress the vortex-induced vibration response. The results demonstrate that the vibration suppression effect of end faces with hemispherical shape is the best compared with the footstep shape and parabolic shape. For the plugging velocity, high-velocity plugging can induce stronger water hammer phenomenon, leading to destructive vibration of pipelines. In addition, the active spoiler device with two relative spoilers achieves the best vibration suppression effect, and the average fluctuation rate has decreased by 7.6%. The experimental research can ensure the safety of plugging operation, which is beneficial for preventing pipeline failure.

Experimental Investigation on Near-Field Acoustic Propagation Characteristics of Leakage Detection in Submarine Pipelines

The leakage of subsea oil and gas pipelines can have adverse impacts on production progress and the ecological environment. Investigating the sound source and near-field sound propagation of pipeline leaks is essential for understanding the acoustic characteristics of and variations in these leaks. Such understanding is significant for the accurate detection and location of small leaks in pipelines. In this study, we designed an experimental system to study the characteristics of leakage sound signals. We introduced the formation mechanism of leakage sound sources and reviewed corresponding theoretical research. The leakage sound signal’s characteristic frequency range was determined to be between 1 kHz and 2 kHz. We examined the effects of pipeline pressure, leakage aperture, and detection distance on the acoustic signal characteristics. The results show that as internal pipe pressure increases, the leakage sound signal intensity first increases and then decreases. As the leakage aperture increases, the intensity of the leakage sound signal increases. Within a short distance, the intensity remains consistent regardless of detection distance. The results of this experimental study can guide the acoustic internal detection of pipelines. This study has practical significance in the timely detection of small leaks in pipelines and preventing leakage accidents from occurring.

A WebGPU-based acoustic wave simulator for ultrasound NDT

Ultrasound NDT is a standard industrial technique for health monitoring and flaw identification in several structures, such as subsea oil pipelines. Its primary purpose is to form a representative image of the internal structure of the inspected object, which provides, in many cases, early warning of structure discontinuities, making it possible to reduce repair costs and mitigate risks. One of the imaging methods that has been receiving increasing attention in the ultrasound and seismology communities is the Full Waveform Inversion (FWI), which estimates the velocity model for the inspection area by confronting the acquired information obtained by the NDT system with theoretical simulated data. Since FWI algorithms rely on successive ultrasonic wave simulations, it is essential to ensure that each simulation is optimized and contributes little to the total running time. Acoustic wave simulations can be optimized using a graphical processing unit (GPU), which provides hardware acceleration through parallelism, where each point of the simulated area can be computed simultaneously. Among all available GPU APIs, WebGPU is the next-generation standard graphics Web API that exposes modern computer graphics capabilities by giving the user low-level, general-purpose access to the GPUs. This API is designed to efficiently map to native GPU APIs, which enables applications to run on different GPUs, making implementations more scalable and interchangeable. Motivated by this flexibility, we explore the acceleration capabilities of the WebGPU API by implementing a WebGPU-based acoustic wave simulator for ultrasound NDT.

Investigation of subsea oil pipeline rupture

In the current work, a full-bore rupture in the form of a fast-running ductile fracture has occurred at an 18-inch offshore pipeline in the subsea portion. The pipeline was constructed from longitudinal seam welded pipe conforming to API 5L Grade X42. A subsea survey using the remote operation vehicle showed a pipeline rupture at a depth of 2756 in. from the sea surface. Shiny scratch marks on the outer surface of the pipeline at the rupture location were observed as well. The visual examination revealed that the crack originated at a sharp weld toe angle (149°) at the outer surface. The crack originated in the HAZ region and propagated along the longitudinal seam weld. The rupture origin was a fatigue pre-crack of 0.078-inch depth and 6.7-inch length that propagated at a sharp weld toe angle during the pipeline service life. The stress analysis revealed that the burst was not due to the operation pressure, but rather due to stresses introduced by a sharp tool dragging over the bare pipeline surface. The tool introduced huge external stresses to the pipeline. Both of the internal pressure and the external stresses contributed to the crack propagation during the rupture.

Experimental investigation to elucidate the hydrate Anti-Agglomerating characteristics of 2-Butoxyethanol

To alleviate the severity of hydrate formation in subsea oil and gas pipelines, the injection of anti-agglomerants (AAs) is one of the promising approaches. In this work, we investigate the hydrate anti-agglomerating characteristics of 2-butoxyethanol, also called butyl glycol ether (BGE), which has been reported in the literature as an effective synergist for kinetic hydrate inhibitors (KHIs), and a solvent for low dosage hydrate inhibitors (LDHIs). In view of its hydrophobic and hydrophilic moieties, we evaluate the adsorption affinity of BGE for the oil–water interface employing the interfacial tensiometer (IFT) apparatus. Moreover, a micromechanical force (MMF) apparatus was used to probe the interfacial behavior of hydrate particles, wherein we measured the cohesive forces between cyclopentane hydrate particles in the presence of BGE at atmospheric pressure and 274.2 K. The kinetics of methane hydrate formation and resistance-to-flow were assessed while measuring the dynamic pressure–temperature data and motor torque signals alongside with visual observations, respectively, employing a high-pressure visual autoclave (HPVA). IFT results reveal the strong surface active properties of BGE with a substantial reduction in oil–water interfacial tension at ambient conditions. However, no considerable change in the cohesive forces between cyclopentane hydrate particles was observed through MMF measurements. In contrast, HPVA results reveal that the addition of BGE enhanced the kinetics of methane hydrate formation; however, the corresponding torque pattern/visual interpretations indicated an anti-agglomerating action of BGE. While synergistically combining the BGE with under-inhibited dosages of mono-ethylene glycol, we further demonstrated a significant improvement in the hydrate transportability, wherein this synergism led to a non-plugging scenario (flowable hydrate slurry). Our findings will offer new insights into the development of new anti-agglomerant chemistries.

Context-based and image-based subsea pipeline degradation monitoring

This research examines the factors contributing to the exterior material degradation of subsea oil and gas pipelines monitored with autonomous underwater systems (AUS). The AUS have a role of gathering image data that is further analyzed with artificial intelligence data analysis methods. Corrosion and potential ruptures on pipeline surfaces are complex processes involving several competing elements, such as the geographical properties, composition of soil, atmosphere, and marine life, whose eflt in substantial environmental damage and financial loss. Despite extensive research, corrosion monitoring and prediction remain a persistent challenge in the industry. There is a lack of knowledge map that can enable image ausing an AUS to recognize ongoing degradation processes and potentially prevent substantial damage. The main contribution of this research is the knowledge map for increased context and risk awareness to improve the reliability of image-based monitoring and inspection by autonomous underwater systems in detecting hazards and early signs of material degradation on subsea pipeline surfaces.

Residual strength prediction of X80 steel pipelines containing group corrosion defects

As subsea oil and gas pipelines are corroded by moisture, soil, and other external factors, their surfaces develop groups of corrosion defects, which are prone to stress concentration and affect the residual strength of the pipeline. To this end, a finite element (FE) model of an X80 pipeline containing group corrosion defects is established here using ABAQUS. Considering the influence of various defect sizes on the residual strength of the pipe, 46 sets of failure data for group corrosion pipes with different geometries and 364 sets of maximum von Mises stresses versus internal pressure for different operating conditions were obtained. The accuracy of the FE model was verified using burst tests. The residual strength prediction model of the pipes was obtained by 1stopt software. The results show that the key factor affecting the residual strength of pipes containing group corrosion defects is the depth of the deepest defect and the strength of the interaction between the group corrosion defects. Based on the DNVRP-F101 standard, a more accurate method for calculating the failure pressure of group corrosion pipes was obtained by introducing correction factors. The results of this study can provide theoretical support for the safe management of group corrosion X80 pipelines.

Dispersion modeling of underwater oil released from buried subsea pipeline considering current and wave

Marine oil release accident may pose a serve threat to marine environment. Modeling of underwater oil dispersion is helpful for risk assessment and emergency response of marine oil spill accident. This paper presents a Computational Fluid Dynamics (CFD) model to describe the dispersion behavior of oil released from buried subsea oil pipeline leak considering current and wave. The numerical model is validated by repeating the small-scale experiments. A comprehensive simulation of underwater oil dispersion from seafloor soil to sea surface under the combined action of wave and current is carried out. Effects of oil density, oil release rate, soil porosity, current speed on underwater oil dispersion are analyzed. Besides, this study considers underwater oil dispersion from multiple leak points on the pipeline, and a regression model for rapidly predicting oil dispersion is developed by numerical fitting. The uniqueness of this study is that it models underwater oil dispersion considering the seafloor soil and the combined action of current and wave. The presence of seafloor soil has a significant effect on oil migration shape and trajectory, and the variation of soil porosity has little effect on the dispersion distance of crude oil plume. Essentially, this study can be useful for the safety-related applications in marine oil spill accidents.

A data-driven prediction model for maximum pitting corrosion depth of subsea oil pipelines using SSA-LSTM approach

Pitting corrosion is considered to be one of the most dangerous failure forms of offshore steel structures, and corrosion depth is treated as an important indicator of corrosion condition. This paper presents a data-driven model to predict maximum pitting corrosion depth of subsea oil pipelines using the integrated SSA and LSTM approach. LSTM is utilized to learn the relationship between pipeline corrosion depth and its influencing factors. SSA with the strong global search ability and the fast convergence speed is used to optimize hyperparameters of LSTM model to improve its prediction accuracy. A total of 300 samples of maximum pitting corrosion depth of subsea oil pipelines are used to develop the data-driven model. These data are divided into training set and testing set to train and verify the model, respectively. The developed model is compared with LSTM alone and SSA-BP model. The results indicate that SSA-LSTM model performed superior in the prediction accuracy and robustness which evaluation parameters are the smallest values in these models (MAE = 8.84%; RMSE = 0.0607; MSE = 0.36%; MAPE = 9.58%). The developed model can serve as a useful online tool to support the digitalized safety of subsea process systems.

A probabilistic framework for risk management and emergency decision-making of marine oil spill accidents

Offshore oil spills may pose a severe threat to marine ecological environment. In this paper, a new methodology based on Bayesian network (BN) and Influence Diagram (ID) is developed for risk management and emergency decision-making of marine oil spill accidents. The methodology integrates risk management before accident and emergency response after accident, which can balance risk and cost, and render an optimal decision-making. Marine oil spill scenarios including root causations, intermediate and consequent events are identified and modeled using BN considering the dependencies and multi-state of incident process nodes. The probabilities of offshore oil spill incident and the resulting ecological disasters are estimated. The prevention and mitigation measures marine oil spill incidents are identified and added to BN for developing Bayesian ID model, in which the cost and utility of implementing each safety measure are considered. Bayesian ID model can estimate the cost and utility of all safety strategies, and the optimal risk management and emergency strategy are determined by balancing the cost and utility. A case study of marine oil spill accident due to subsea oil pipeline leak is used to illustrate the methodology. It is observed that the methodology can efficiently support the decision-making of oil and gas sector in risk management and emergency response of offshore oil spill accidents.

A review of the potential risks associated with mercury in subsea oil and gas pipelines in Australia

Environmental context The oil and gas industry has a significant liability in decommissioning offshore infrastructure. Following decommissioning, subsea pipelines could be left on the seabed to provide artificial reefs. Mercury is a contaminant of concern which could remain within pipelines. There are gaps in our knowledge on how mercury moves through the marine environment. We review the current science and identify future research needs to understand potential impacts from mercury in subsea pipelines which will better inform decommissioning activities globally. Abstract In the coming years, the oil and gas industry will have a significant liability in decommissioning offshore infrastructure such as subsea pipelines. The policies around decommissioning vary depending on regional policies and laws. In Australia, the ‘base case’ for decommissioning is removal of all property and the plugging and abandonment of wells in line with the Offshore Petroleum and Greenhouse Gas Storage (OPGGS) Act 2006. Options other than complete removal may be considered where the titleholder can demonstrate that the alternative decommissioning activity delivers equal or better environmental outcomes compared to complete removal and meets all requirements under the OPGGS Act and regulations. Recent research has demonstrated that decommissioning in situ can have significant environmental benefits by forming artificial reefs, increasing marine biodiversity, and providing a potential fishery location. An issue, which has been given less attention, is around contaminants remaining within decommissioned infrastructure and their potential risks to the marine environment. Mercury is a contaminant of concern known to be present in some oil and gas pipelines, but the potential long-term impacts on marine ecosystems are poorly understood. We present a synthesis of information on mercury cycling in the marine environment including key drivers of methylation in sediments and ocean waters, existing models to predict methylmercury concentrations in sediments, and toxicological effects to marine biota. We discuss the applicability of existing water and sediment quality guidelines, and the associated risk assessment frameworks to decommissioning offshore infrastructure contaminated with mercury. Globally, research is needed to provide a comprehensive risk assessment framework for offshore infrastructure decommissioning. We recommend future areas of research to improve our understanding of the potential risks associated with mercury in subsea oil and gas pipelines.

Application of Erica Tool to Assess Risk to Marine Biota: Case Study Using Norm By-Products from a Decommissioned Offshore Subsea Oil and Gas Pipeline

Application of Erica Tool to Assess Risk to Marine Biota: Case Study Using Norm By-Products from a Decommissioned Offshore Subsea Oil and Gas Pipeline

A KPCA-BRANN based data-driven approach to model corrosion degradation of subsea oil pipelines

Corrosion is an important reason for the structural degradation of offshore oil pipelines, which may cause serious economic loss and environmental pollution. Nowadays the digitalized devices make a number of monitoring data become available. The prediction of corrosion degradation based on monitoring data becomes an efficient tool to prevent corrosion failure of offshore oil pipelines. This paper integrates KPCA and BRANN techniques to develop a novel data-driven model for corrosion degradation prediction of offshore oil pipelines. The model can eliminate the redundant information from the original monitoring data and improve the robustness by regularization constraints. KPCA is applied to reduce the dimension of the factors affecting pipeline corrosion, and the extracted principal components of corrosion variables are inputted in BRANN to build a corrosion degradation prediction model. The data with dimension reduction are divided into training set and validation set. The model is compared with BRANN alone and KPCA-LMANN model, which indicates KPCA-BRANN model presents superiority in the robustness and prediction accuracy (MSE = 0.46%; R2=0.99). The proposed model can be used as an online prediction module of digitized process safety system, and support the reliability assessment and maintenance planning of corroded subsea pipelines.

Design on non-stop transportation plugging device for subsea pipeline

The process of plugging with pressure outside the subsea pipeline is cumbersome. The common technology cannot transport oil and gas during the maintenance process, and a new type of subsea pipeline non-stop transportation plugging technology is proposed. In this paper, an oil and gas pipeline with a diameter of 324mm and a pressure of 3MPa is taken as the research object for overall design and feasibility analysis. The anchoring and sealing performance of the packer is calculated, checked and analyzed using the element method. The results indicated that the plugging device can meet the plugging requirements of non-stop transportation of subsea oil and gas pipelines in maintenance.