bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting the Rate of Cement Plug Failure
Authors: Charabin Scott , Frigaard Ian A. 
Published: September 2023

Abstract
Plugging is an essential part of decommissioning wells. Often cement plugs are set at various depths to isolate critical zones of interest. These zones can include production zones, aquifers and surfaces, ensuring the wellbore is isolated correctly. The cement plug should hydrate and form an impenetrable barrier between the subsurface and the surface. Since the cement slurry, containing a yield stress, is typically denser than the fluid below, there is a tendency to destabilize mechanically. Proper selection of cement properties, namely the yield stress, is therefore essential to the success of the abandonment process. If the cement does not set correctly, the well integrity is compromised and another cement plug will need to be placed.
This motivates the study of this paper, we study the interface between the cement and lighter Newtonian fluid. Over the initial setting time, the interface can become unstable allowing light fluid to propagate upwards into the denser fluid. Experimental studies conducted with water under a denser yield stress fluid show that the interface usually takes the form of a long finger moving centrally upwards. If this finger can reach a critical height in the cement plug before it sets sufficiently, the plug will lose its integrity and fail. Therefore, being able to predict the velocity of the finger is of critical importance. We scale our experimental setup to give an accurate representation of a typical western Canadian well. We can then derive an analytical expression for the flow rate and mean velocity of both the viscous finger and the dense fluid flowing down. We then explore this finger propagation by varying the critical parameters of the heavier fluid, namely the density and yeild stress. Experiments show that the model accurately predicts the velocity of the finger for a range of rheological properties and densities. The speed of the finger is found to be governed by the yield stress, the density contrast, and the ratio of effective viscosities.
Modeling Oceanic Variables With Graph-Guided Networks for Irregularly Sampled Multivariate Time Series
Authors: Fialho Coelho Jefferson , Rodrigues de Barros Marcel , Fabricio Deberaldini Netto Caio , Marino Moreno Felipe , Palmiro de Freitas Lucas , Sproesser Mathias Marlon , Gagliardi Cozman Fábio , Dottori Marcelo , Satoshi Gomi Edson , Aoun Tannuri Eduardo , Helena Reali Costa Anna 
Published: September 2023

Abstract
Forecasts of ocean dynamic variables are essential to ensure safe operations at sea and in coastal regions. However, one difficulty with such forecasts is the need to handle multiple scales and repetitions in data, as well as noise caused by sensors malfunction. We describe a data-driven approach to predict oceanic variables under those circumstances; we take as a case study the prediction of water current velocity and sea surface height in an estuarine system in the southeastern coast of Brazil. We propose a generic method that can be applied to a variety of practical cases with little to no adaption, using a Graph Neural Network to model the system dynamics. We provide evidence that our method produces robust forecasts. It does so by employing forecast data from the state-of-the-art physics-based model “Santos Operational Forecasting System” (SOFS). The approach has lower computational costs and requires almost no domain-specific knowledge. We compare our model with SOFS and ARIMA-like forecast models in experiments.
New Temporal Approach to Evaluate the Lateral Buckling of Armour Wires
Authors: Bouy Ludovic , Frigeri Phellip , Lemonnier Gilles , Estrier Pascal 
Published: September 2023

Abstract
This paper presents a novel approach to manage irregular external loads thro ugh an enhanced design of unbonded flexible pipeline caused by lateral buckling of tensile armour wires. The design challenge is to predict the armour wire kinematics due to random loading conditions.
Over the past decades, efforts have been made to simulate and model lateral buckling phenomenon. Based on more than a hundred full scale tests, including deep immersion performance tests and hyperbaric chamber tests, a design approach was established that reproduces lateral buckling. The analyses performed considered regular sinusoidal loading corresponding to extreme sea states, often leading to overconservative combinations of curvatures and axial compressions. Wire displacements and stress states of steel wires were predicted using in-house software with the aforementioned cyclic loading. This methodology has shown room for improvement to decrease the conservatism and make sure we propose the most optimized armour wire geometry for a flexible pipeline designed to lateral buckling. In this paper, it is demonstrated that loading of compression and bending derived from stochastic extreme sea states allows us to bring the migration calculation to a higher level of accuracy. As a result, armour wires achieve their final migration state with lower stress values with stochastic approach with extreme sea states rather than the regular one.
Some technical challenges appeared when establishing this new approach. For example, bending cycles order as well as the sea states order impacts on wire kinematic and stress state. These observations, shared in this paper, concluded that a temporal approach is required to properly estimate lateral buckling risk when considering irregular loads. A key aspect identified during the development is the need of having two calculation modes when performing lateral buckling calculation with a temporal approach. The first mode allows to manage temporary operation by disregarding sea states order which could be very useful for simulating lateral buckling during installation sequence, whereas the second mode allows to evaluate lateral buckling during service line operation by considering the impact of all the sea states. Calculating armour wire kinematics migration during an entire service life, considering all the sea states, was another challenge requiring significant dedicated software developments. Impact on calculation time has been scrutinized and specific methodology has been implemented to optimize calculation time. Stress comparisons between classical regular approach and this new temporal – two calculation method are presented in this paper to illustrate the improved accuracy.
This temporal – two calculation methods also result in improved installation weather windows, and optimized armour wire selection. Finally, this methodology has been reviewed and certified by an Independent Verification Agent.
Research on Offshore Engineering Equipment Industry in Shandong Based on Sustainable Development
Authors: Deng Yue , Zhao Jingli , Duan Xiaofeng , Song Weiling , Guo Yue 
Published: September 2023

Abstract
Offshore engineering equipment industry is at the core of the marine industry value chain and an important foundation for the development of blue economy. Shandong was selected as the research area in this paper. Comprehensive strength of five industries — offshore oil and gas industry, offshore electric power industry, offshore fishery, offshore mining industry and offshore seawater utilization industry were analyzed from three dimensions of resource endowment, industrial development level and existing production capacity. Based on sustainable development, development suggestions of offshore equipment industry in Shandong were given.
A Method for Optimization of Sensor Locations for Inverse Calculation of Impact Load on Stiffened Panel
Authors: Zhou Xueqian , Shen Xingzhi , Xu Yishi , Ren Huilong 
Published: September 2023

Abstract
There are many scenarios in the area of ships and marine structures where impact on structure members like stiffened panels where the impact loads are difficult to directly measured and one may need to turn to inverse calculation.
The inverse calculation of impact load is very important as impact loads are characterized by short action time and large amplitude, which have adverse effects on structural safety. In practice, one of the difficulties in inverse calculation of impact load is the need of a large number of sensors, which means high cost and huge amount of computation. Therefore, it is necessary to optimize the layout of sensors for inverse calculation of impact load. To investigate the method for optimization of sensor locations for inverse calculation of impact load on stiffened panel, the inverse calculation results of different sensor layout of the stiffened panel are analyzed by applying Particle Swarm Optimization. Based on the optimization principle of Particle Swarm Optimization, a fitness function with the overall relative error and cosine similarity as the judgment criteria is established. The inverse calculation of impact loads on the stiffened panel is carried out with different number of calibration points and sensors. The regularization method is applied to deal with the ill-conditioning of matrix. The effects of the number of calibration points and sensors on the inverse calculation of impact loads are discussed. An optimal sensor layout that meets the requirements of the fitness function is found under a calibration point number and sensor number by Particle Swarm Optimization.
The Adaptation of Condition Monitoring Methodologies From Fixed Wind and Floating Oil and Gas to Floating Offshore Wind
Authors: Jayasinghe Kanishka , Gumley Jonathan , Thomas Clare , Lemmer Frank , Raach Steffen 
Published: September 2023

Abstract
As the Floating Offshore Wind Turbine industry approaches the transition from demonstrators to commercial scale farms, condition monitoring systems will be integral to risk management. Scalable condition monitoring solutions exist for both Fixed Offshore Wind and floating Oil and Gas, however a holistic solution addressing aerodynamic and hydrodynamic challenges on a floating wind unit is lacking.
Where sensors should be minimized, or for unmeasurable parameters, digital twins offer an alternative for predicting major component condition, relying instead on numerical models based on floater global response and metocean conditions.
This paper demonstrates the potential of reconstructed load signals, state-of-the-art sensors and first principles physics-based digital twins using approaches from the Wind and Oil and Gas sectors. Existing motion-based integrity monitoring methods are adapted to a real-time reduced-order model of a floating wind unit. Specifically, a state-observer model is used to reproduce position and mooring tension, enabling mooring failure identification and fatigue tracking.
The methods are demonstrated through a 15 MW synthetic case study, including examination of the impact of noise and sensor loss on reliability. The results show that the integration of digital twins into sensor-based monitoring systems can reconstruct missing data with sufficient certainty to facilitate early detection of failures.
On the Relationship Between Spectral Models of Ice Drift and Wind Turbulence
Authors: Sinsabvarodom Chana , Leira Bernt J. , Høyland Knut V. , Chai Wei , Naess Arvid , Radhakrishnan Gowtham 
Published: September 2023

Abstract
At present, there is quite limited research activity related to mathematical models of the ice drift spectrum. The intention of this work is to propose a novel mathematical model of a generalized ice drift speed spectrum to describe the ice drift behavior in the frequency domain. The drift of sea ice is naturally influenced by external forces such as wind stress at the air-ice interface, water stress at the water-ice interface, the Coriolis force, pressure gradients due to sea surface tilting, and internal stress within the sea ice itself. Typically, wind dominates the ice drift at higher frequencies, while current is likely to play an important role in the lower frequency range. This is due to the slow rate of change for the ocean current. Typically, sea ice will drift at approximately 2–3% of the wind speed as referred to a height of 10-meter above the ocean surface in the Arctic region. The magnitude of the ice drift speed can approximately be predicted by the Nansen number corresponding to the drift speed magnitude as a percentage of the wind speed. The physical connection between the wind speed and the ice drift speed is presently utilized in order to generate a generalized ice drift spectrum. The ice drift data is collected from local subsurface measurements by means of acoustic Doppler current profilers (ADCP) in the Beaufort Sea. The frequency spectra of the wind speed and ice drift speed are calculated by application of the Fourier transform (as implemented in the WAFO software) based on the measured time series. It is found that the sea ice drifts at around 2.5% of the wind speed in the winter season (which corresponds to non-free drift conditions). However, during the summer season the sea ice tends to drift faster than 2.5% of the wind speed (which corresponds to free drift conditions). According to the scaling relationship between the ice drift speed and the wind speed, the Kaimal turbulence spectra are adopted to describe the ice drift behavior. This provides a good match for the winter season. However, the empirical ice drift spectrum contains higher energy levels than the Kaimal turbulence spectra in the high frequency range during the summer season. Accordingly, a generalized ice drift spectrum is proposed in the present paper, which is developed based on expressions for the general turbulence spectrum. The corresponding expression is more flexible in order to capture the ice drift behavior in the high frequency range for both the winter and the summer seasons. The generalized ice drift spectrum is found to provide a better match to the empirical spectra from ADCP measurements than the Kaimal turbulence spectrum.
A Data Driven Decision Support System for Structural Safety of Ships Moving in Waves
Authors: Zhou Xueqian , Yang Yu , Liu Yujie , Feng Guoqing , Ren Huilong 
Published: September 2023

Abstract
The safety of ship hull structure is the most important and fundamental premise of ship operational safety at sea. For ships moving in large waves, the wave loads vary with the loading condition, ship speed and heading, incorrect operation decisions may result in large wave loads on the ship and cause severe accidents. In recent years, the technological advances made in the durability and stability of sensors, data acquisition, data processing units have made it possible to close monitor the stresses in the hull structures of ships. Such technologies are not only an approach for the crew to identify the structural state of the ship hull, but also provide the possibility of sophisticated decision support of safe operations. Although it is possible to reduce vertical bending moment by changing the heading from head seas to quartering seas, but the increasing horizontal bending moment and torsional moment might become a new threat to the structural safety of ships with large deck openings. In this paper, a data driven decision support system for structural safety of ships moving in waves is proposed. The stresses in the deck and in the bottom structure of a ship are used to calculate vertical bending moment, horizontal bending moment and torsional moment in real time, the assessment of overall strength of the ship hull under the wave loads is conducted. To construct a model for the proposal of safe operation of ships driven by monitor data, a method is devised for accurate identification of current navigation parameters based on the sensor data, which are then used for the calculation of parameters for safe operation of ship moving in waves. The method is applied to the case of a container ship moving in waves, and some conclusions are drawn based on the analysis of the results.
Investigation of the Formation and Detection of Casing-Cement Debonding in Small Scale Samples
Authors: Feneuil Blandine , N'gouamba Elie , Larsen Idar , Skorpa Ragnhild 
Published: September 2023

Abstract
In oil and gas wells, cement is generally placed in the annulus between the steel casing and the rock formation to avoid migration of fluids from the formation to the well. Though, during the operation of the well, casing dilatation and contraction may lead to the loss of the sealing ability of the cement annulus: casing dilatation tends to induce cracks in the cement, while casing retractation may create casing-cement debonding (microannulus). At the end of the well’s life, when the well is to be abandoned, it is essential to be able to evaluate the integrity of the cement, to decide whether the cement annulus must be repaired or replaced during the plugging operation.
In this study, we investigate the use of a pulse-echo and a pitch-catch ultrasonic tools to assess the severity of cement-casing debonding.
In the first stage, we measure the evolution of acoustic logs just after the sample preparation. We compare the evolution of the logging curves with measurements of the cement strength with Ultrasonic Cement Analyzer. We observe that for the samples cured at room temperature and pressure, the quality of the bonding first increases before the setting time, then tends to decrease due to debonding.
In the second stage, we simulate defects at the casing-cement interface by placing tape stripes of different thickness. We observe how these defects affect the acoustic logs and observe the morphology of the defects on Computed Tomography pictures, to analyze the relation between the logs and the geometry of the microannuli.
Laboratory-Scale Experiments to Predict Barite Sedimentation in Drilling Fluids in Wells
Authors: Feneuil Blandine , Lund Bjørnar , Skorpa Ragnhild 
Published: September 2023

Abstract
Barite sedimentation in drilling fluids at rest is a challenge for plugging and abandonment operations (P&A) of oil wells. On the one hand, the barite sediments can complicate the operations by preventing casing removal. On the other hand, they could be used as a barrier material. Therefore, it is essential to be able to understand the sedimentation process in order to predict the sealing properties of the sedimented material. As in-situ measurements can be difficult and time-consuming, it would be helpful to be able to predict the sedimentation properties of a drilling fluid from laboratory experiments. In this paper, we perform small-scale experiments on barite sedimentation and focus on how these results can be used to predict barite sedimentation at field scale.
We perform several experiments using two oil-based drilling fluids, with various barite content. First, we investigate the effect of scale by observing the drilling fluid left at rest for two months in static cylinders of different heights and diameters. We observe a phase separation in the drilling fluid columns: a layer of dark liquid appears at the top. We track the growth of the liquid layer with time and observe how it is affected by the barite content and the sample dimensions. Secondly, rheological measurements are performed on the liquid layer to investigate its composition. We also measure the yield stress of the drilling fluid, i.e., the stress required to make the fluid flow and investigate how it is related to the barite content. We observe that the drilling fluids are strongly thixotropic, as the yield stress increases from a few Pascals to several 10 Pa when left at rest for several days. Finally, we centrifuge small samples and compare phase separation caused by centrifugation with phase separation caused by static sedimentation. We note that in centrifugation tests, the liquid layer appears only if the centrifugation velocity is large enough. We discuss whether and how centrifugation can help to predict barite sedimentation at field-scale.
Probabilistic Approach for Fatigue Life Extension of Subsea Wells Using Pressure Testing
Authors: Fjeldstad Arne , Hørte Torfinn , Sigurdsson Gudfinnur , Sætre Stian 
Published: September 2023

Abstract
This article presents a fatigue life extension procedure for subsea wells based on probabilistic fracture mechanics analysis. The dominating fatigue loading of subsea wells occurs when a drilling rig with a marine riser and blow out preventer is connected to the subsea wellhead, imposing bending loads due rig motions and wave loads acting on the riser. The challenge of life extension of these type of components is that the fatigue governing hot spots are not easily available for inspection. This makes it difficult to document safe operation in cases when the calculated fatigue damage has exceeded the acceptance criterion specified in the design code. However, during the last decade significant effort has been directed towards reducing the external loads on subsea wells. This has made it possible to document sufficient fatigue strength for continued operation by assuming the presence of relatively large cracks. This has in turn reduced the need for using inspection methods that can detect small crack and allow the use of less efficient, but practicable methods of estimating the size of potential cracks, such as pressure testing. This article presents an approach where probabilistic fracture mechanics analysis is used to estimate the size of a potential fatigue crack based on a successful pressure test and document the time required for continued operation or plug and abandonment within the required safety level.
Response Analysis of Composite Blades of Offshore VAWT Using CFD and FSI for the Indian Ocean
Authors: Arora Prince , Parmeshwar Atkale Prashant , Prasad Patel Badri , Ahmad Suhail 
Published: September 2023

Abstract
Conventional HAWTs dominate the wind industry commercially, whereas VAWTs are receiving researchers’ interest now across the globe due to their inherent advantages over HAWTs. VAWTs are more suitable for the offshore environment due to their omnidirectionality and lower center of gravity. The centrifugal forces play a dominant role in the bending of the vertical axis wind turbine blades in addition to aerodynamic forces. Thus, there is a scope for the optimization of VAWT blades’ wall thickness and material such that the contributions of aerodynamic and centrifugal forces in the bending of blades are equalized. Further, the probabilistic nature of the wind causes more complexities in the system. So far, many studies have been performed employing computational fluid dynamics and FSI approaches to analyze VAWTs. However, only a few publications give insight into its structural behaviour as a result of interaction with the random nature of the wind velocity.
The present study is carried out in two steps. The first step involves the probabilistic analysis of the actual wind speed of 13 months (1 November 2017 to 30 November 2018) recorded using LIDAR in the Gulf of Khambhat, in the Indian Ocean. The probabilistic wind data is then used to estimate the wind-induced pressure on blades using the standard commercial CFD tool, ANSYS Fluent considering a three-bladed vertical axis wind turbine with a symmetrical NACA airfoil. The aerodynamic pressure is estimated based on the Reynolds-Averaged Navier Stokes (RANS) equations.
The latter part of the study involves structural analysis of the hollow composite blades of VAWT due to the aerodynamic pressure estimated from the first part and centrifugal forces due to rotation. The risk of failure arises due to the exceedance of stresses/strains beyond a threshold. Each hollow blade is modeled with different layers of material and thickness to minimize the blade mass such that the stresses/deflections are within the allowable limits and blades do not exhibit dynamic instabilities such as flutter. The study will be useful for an improved and efficient design of the VAWT in an Indian offshore environment.