bluuebunny/crossref_metadata_2025_split huggingface dataset:
Machine Learning Models for Predicting Cuttings Concentration in Annulus Based on Flowloop Experimental Data
Authors: Purwandari Sartika Dwi , Lund Bjørnar , Hovda Sigve 
Published: September 2023

Abstract
Improper drilling parameter values selection can result in a series of operational problems, such as stuck pipe, wellbore pack-off, reduced ROP, and increased equivalent circulation density. A large fraction of these problems occurs because the well is not sufficiently clean due to cuttings accumulation. Cuttings transport is a complex process that is influenced by drilling parameters such as flow rate, pipe rotation speed, fluid rheology, cuttings properties, and wellbore and drillpipe geometry. Numerous research projects have been conducted to study cuttings transport both using laboratory experiments and numerical approaches to build physics-based cuttings transport models. Yet, a model which can account for all relevant combinations of drilling parameter values with high predictive capability is still out of reach.
In this study, we investigated the use of various machine learning models on this very complex topic. In particular, we focused on the prediction of cuttings concentration based on flowloop experiments from three different research facilities. The data that were collected from the different research facilities have a total of 332 data points. Each data point consisted of these nine input variables: annular wellbore area, eccentricity, rate of penetration, pipe rotation, apparent viscosity, average flow rate, fluid density, cutting size and wellbore inclination. 61 data points were found as outliers from one input variable, namely ROP. Those outliers were decided to be kept due to those outliers were not occurred by error measurement. Therefore, a robust regression technique (Huber Regression) and two types of ensemble learning (Random Forest and Gradient Boosting) were chosen because those machine learning algorithms were not sensitive to the presence of outliers. The data were divided into two groups for training and testing, respectively with proportions 80% and 20%. Those models were trained using a training data group and evaluated using cross-validation to avoid over-fitting. Mean absolute error (MAE) and coefficient determination (R-squared) were used to analyze model performances when models were applied to data testing. The results showed that the two ensemble learning models both had lower mean absolute error and higher R-squared compared to the robust regression technique. Next, Larsen’s empirical approach which is based on the critical velocity concept was compared to the machine learning techniques. According to the performance evaluation results, machine learning models showed better predictions compared to an empirical approach and they had lower MAE and a higher value of R2. GB has the best performance by giving an error of the model prediction about 2.150 % and R2 0.920.
Modelling Hydrate Plug Capacity of Flexible Pipes
Authors: Schmidt Henrik Blicher , Solfeldt Thomas Iversen , Pedersen Tommy 
Published: September 2023

Abstract
Hydrate plug detection and removal in flexible pipe has gained increasing attention from operators and at the same time not much has been published on the subject. When operating flexible pipe for hydrocarbon applications there is a risk of hydrate formation. Hydrates can block the bore of the flexible pipe and differential pressure can form across the hydrate plug. This differential pressure can damage the inner layers of the flexible pipe.
The objective of the present study is to estimate the differential pressure capacity of the flexible pipe.
Hydrates most often form during production stop periods. When the well is started up the lack of flow can be used to detect a hydrate plug. Either during this detection or during the removal of a hydrate plug, the pipe can be subject to a differential pressure across the plug domain. The differential pressure can lead to excessive loading of the pipe layers, especially the carcass and pressure sheath layers.
A numerical model has been developed that can be performed with reasonable computational effort using an in-house pre/post-processor and FE solver. The model adopts the axisymmetrical framework, and the enmeshed domain is limited to the innermost layers, i.e. carcass, pressure sheath, and pressure armour.
The model simulates the hydrate plug by applying Boundary Conditions corresponding to the rigid body motion of the surrounding carcass windings and converting the reaction forces monitored in the model into a differential pressure.
The pressure sheath principal strain and carcass plastic strain are chosen as limiting criteria. The driving factor is the load transfer across each layer while the carcass windings are displaced axially (together with the plug) caused by the load from the differential pressure.
For a given plug length, the differential pressure capacity is evaluated at the “time-step” where the governing strain criteria is exceeded — the reaction forces acting on each carcass winding are integrated into a total reaction force. Finally, the total force is converted into a differential pressure, which is denoted the hydrate plug capacity of the pipe.
An important finding is that the differential pressure capacity increases for longer plug length in a non-linear manner. The non-linear plug length dependence is in competition with the hydrate plug shear capacity assumed to scale linearly with the plug length. The applied differential pressure can then be compared to the hydrate shear capacity thereby establishing if the plug is removed by shearing. The applied differential pressure is subsequently compared to the pipe’s hydrate capacity, showing that the differential pressure is below the pipe capacity for the possible range of plug lengths.
Optimal Energy Management for Zero-Emission High-Speed Passenger Vessels
Authors: Najjaran Samieh , Skjetne Roger , Godø John Martin Kleven 
Published: September 2023

Abstract
To comply with IMO’s regulations on reduced emissions, the maritime industry is investigating various alternatives to achieve zero-emission high-speed passenger vessels (HSPVs). In this work, optimal loadsharing is studied for a given vessel with a zero-emission hybrid driveline with a fuel cell (FC) and a battery. The further aim is to include this as part of a computation model to assess feasibility of zero-emission solutions for passenger transport connections under study along the coast of Norway. A dynamic programming (DP) algorithm is derived to provide the global optimal solution of the loadsharing problem. This will serve as a benchmark for other and more computationally efficient optimization algorithms to be feasible for runtime applications. Here we formulate an alternative optimal loadsharing model based on a linear program (LP) and compare that to the DP. The proposed LP and DP are applied to a numerical model for an existing HSPV operating along a given route. AIS data is used to extract the route information and power load profile of the vessel. The results demonstrate a step towards an overall methodology for assessing the feasibility of a vessel and an onboard propulsion and power system to allow for zero-emission passenger transport.
Multiphase Seepage Flow Characteristics of Micro-Fractures in Subsurface Reservoirs Using the Lattice Boltzmann Method
Authors: Pu Dan , Shen Linfang , Wang Zhiliang , Li Miao , Li Zhenquan , Wang Pengyu 
Published: September 2023

Abstract
The traditional Shan-Chen pseudo-potential model has limitations, such as pseudo-velocity, density ratio limitation, and thermodynamic consistency defect. A method based on the improved Shan-Chen pseudo-potential model to study fluid flow in rock microfractures using the multiple-relaxation-time lattice Boltzmann method is proposed and validated using three arithmetic cases. The geometric characteristics (height and spacing) of the rough elements are varied to analyze the joint effects of rough elements and infiltration conditions on the multiphase seepage in microfractures. Rough microfractures are simulated using regular rough elements of different shapes, including rectangular, trapezoidal, and triangular rough elements. With the increase in the rough elements height, for the microfractures at the wall contact angle θ = 145.5°, 117.2°, and 67.0°, the flow velocity decreases and then increases; for the θ = 93.0° micro fissure, the fluid flow velocity decreases to stationary. With the increase in the rough element spacing, for the θ = 145.5° micro fissure, the liquid flow rate continuously increases; for the θ = 117.2°, 93.0°, and 67.0° micro fissures, the liquid flow rate continuously decreases. This study is expected to guide future researchers and engineering applications in terms of subsurface reservoirs.
As-Built Carcass Fatigue Modelling
Authors: Bonanni Michele , Nott Phil , McCormick Andrew , Bailey Trevor , Roberts Andrew 
Published: September 2023

Abstract
In rough bore flexibles, the carcass sustains external pressure loads. The design of the carcass section is such that displacements due to pipe bending do not significantly load the carcass. Cyclic loading is therefore typically avoided by design. Several decades of operational and dynamic testing experience indicate that these designs are indeed effective.
Nevertheless, an analytical methodology for the carcass is advisable in order to clear concerns regarding pipes with stiffer carcass layers or with tolerances close to the manufacturing limits. This work assesses the service life of as-built carcass and investigates sensitivities to carcass pitch and barrier intrusion.
For this purpose, a novel approach to carcass SN curves is presented. The use of these SN curves in the finite element simulations for the service life estimation improves the fatigue life prediction capability and allows the exploration of sensitivities in manufacturing tolerances — potentially leading to the relaxation of carcass tolerance limits, reducing the onus on the manufacturing of adjacent layers and thus improving the performance of the pipe overall.
Coupled Numerical Model for Residual Liquefaction With Partial Dynamic Approach
Authors: Cui Lin , Wan Zhipeng , Jeng Dong-Sheng 
Published: September 2023

Abstract
The evaluation of the seabed liquefaction is one of the key factors for the design of foundation of marine infrastructures. In this paper, a new numerical model developed within the framework of OpenFOAM® is proposed by two new features: (1) coupling oscillatory and residual mechanisms; and (2) adopting partially dynamic soil behavior in the existing models. The proposed numerical model predicts reasonable results comparing with the existing experimental data from wave flume tests. With the coupling model, a new liquefaction criterion is proposed to cover both oscillatory and residual liquefaction. Both wave and current loading are considered in the numerical example. Numerical examples conclude that the forward current can increase the maximum liquefaction depth by 23% after 35 wave cycles comparing to the wave only case.
Probable Ice Impact Locations and Magnitudes on a Naval Hull Form in Forward Transit Through Marginal Ice Zones
Authors: Bryson Edward , Quinton Bruce W. T. , Daley Claude 
Published: September 2023

Abstract
Operational capability assessment of ships in the Arctic have traditionally focused on icebreaking hull forms. The classification of these capabilities resulted in the development of the International Association of Classification Societies (IACS) Unified Requirements for Polar Ships, which requires the hull structure to withstand a predetermined glancing bow impact. The assumptions made when developing the Polar Class Rules, such as the collision with a thick and semi-infinite multiyear ice floe, slow speeds, and a glancing bow impact on an icebreaking bow shape, are not always valid when assessing the operational capabilities of non-icebreaking hull forms.
The ex-HMCS IROQUOIS was simulated in forward transit through marginal ice zones using the computer program “GEM” to study the location and magnitude of probable ice loads. The collision model was validated using the DDePS case 2a collision scenario (glancing collision on the bow). The model was simulated transiting forward at different speeds through ice regimes with varying identified parameters of interest, namely concentration, ice floe size distribution, and ice floe thickness.
The observed results show most of the high magnitude ice impacts for this naval hull form occurred at or near the stem, and only a few high magnitude impacts on the bow shoulder. This contrasts to an earlier study using GEM where an icebreaking hull form in forward transit through a marginal ice zone experienced a plurality of high magnitude impacts along the bow shoulder. The main reason for the difference is the shape of the bow, with the naval hull form being markedly slender with much lower normal frame angles. These results suggest that both stem and bow shoulder impacts are of importance when assessing the operational capability of naval hull forms in marginal ice zones.
Analytical and Finite Element Assessment of Thermoplastic Composite Pipes Subjected to Axisymmetric, Bending and Thermal Loading
Authors: Caire Marcelo , Luna Araújo Oliveira Pedro , He Yangye , Vinicius Da Cruz Marcus , Augusto Vaz Murilo 
Published: September 2023

Abstract
Thermoplastic Composite Pipes (TCPs) may be employed as an alternative to traditional unbonded flexible pipes for deep water developments. They are usually manufactured with PEEK or PVDF polymeric layers in the inner and outer layers and an intermediate carbon fiber composite laminate. The TCP composition leads to a lightweight pipe with high corrosion and fatigue resistance, but due to high bending stiffness, large drum diameters may be required for installation with the reel method. This paper presents an analytical formulation considering a carbon fiber/PEEK TCP subjected to pure bending. A previously presented analytical formulation for tension, internal and external pressures and thermal loading is employed to separately obtain the axisymmetric and thermal stresses. The temperature dependency of stiffness and strength material properties are considered for both models. The case study combines the axisymmetric and bending model results and compares the results against three-dimensional finite element models. The through thickness temperature profile for the TCP under different internal prescribed constant temperatures (60, 80 and 120°C) and subjected to outer pipe convection to the seawater at 4°C are presented followed by analytical formulation correlation with FEM stress distribution results. The temperature influence on the pipe bending stiffness is also shown. The Maximum Stress and von Mises failure criteria are respectively employed for the laminate and homogeneous layers and failure envelopes are presented for tension and bending loads for each prescribed internal temperature and fixed internal and external pressures.
Verification of Inverse Propeller Moment Estimation Using a Scale Laboratory Rig: Further Results and Discussion
Authors: Nickerson Brendon M. , Laas Jaco , Bekker Anriëtte 
Published: September 2023

Abstract
There has been increasing interest in the loads caused during interaction between ship propellers and ice. Recent research into propeller ice interaction has produced inverse models that can be used to estimate the propeller moment induced by ice impacts. These models rely on the measurement of the output response of the propulsion shaft, which is inverted to obtain the input propeller load. The particular model considered here makes use of modal superposition to invert the measured shaft response. Though the model has been validated numerically and used with full-scale response data, it has not been validated using simultaneous input and output measurements. Reliable full-scale simultaneous measurements can be difficult to obtain due to the harsh conditions experienced during propeller-ice interactions, and the cost involved with direct measurement of propeller loads. Thus, the use of a laboratory rig to verify the inverse method is investigated. An inverse model based on the use of modal superposition to represent the propulsion shaft as a continuous system has been implemented alongside a laboratory scale rig. The input loads and output responses are measured simultaneously during experiments with the scale model. These output responses are provided to the inverse model, and its estimation of the input load are compared to the measured loads. The comparison provides information about the accuracy of the estimations provided by the inverse model. A limitation in the inverse model, that spurious transients at the shaft natural frquency appear in the estimations, has been found and discussed.
Computational Fluid Dynamics Study of a Cross-Flow Marine Hydrokinetic Turbine and the Combined Influence of Struts and Helical Blades
Authors: Wiley Will , Tran Thanh Toan , Lawson Michael , Barrington Matthew 
Published: September 2023

Abstract
A computational fluid dynamics study was performed for a cross-flow marine hydrokinetic turbine. The analysis was done in three dimensions and used the unsteady Reynolds-averaged Navier-Stokes solver in the commercial code STAR-CCM+. The base turbine configuration is the RivGen® Turbine, designed by the Ocean Renewable Power Company. A convergence and uncertainty analysis was performed for both the spatial and temporal discretization; this was done using the base configuration, which features support struts and helical foils. Both struts and helical blades introduce three-dimensional flow effects, influencing the complex flow phenomenon of dynamic stall. The study compares the relative impact of struts on power performance and blade loading for both helical and straight blades, and found that for this turbine the relative loss in power from struts was lower with helical blades.
Time Domain Structural Analysis and Digital Twin Application for Floating Offshore Wind Turbine
Authors: Lim Ho-Joon , Samaria Sagar , Choi Sukjoo , Sablok Anil , Jang Hakun , Koo Bonjun 
Published: September 2023

Abstract
A response-based time domain structural analysis method for offshore floating platforms has been studied and validated. Compared to the conventional load-based and simplified method, the response base method can evaluate structural strength and fatigue damage with higher accuracy, taking into account irregular waves, non-linear environmental loadings, phasing between different loads, non-linear motion responses, and non-linear mooring and riser loadings.
The present study examines the structural assessment of the entire substructure and the turbine tower to substructure connection of a Floating Offshore Wind Turbine (FOWT) platform using a response-based time domain structural analysis. Finite Element (FE) models are constructed for the entire FOWT, and corresponding load components are mapped to the FE model. A fully coupled aero-hydro-servo-elastic analysis software, MLTSIM-OpenFAST, is used to calculate dynamic responses of a FOWT in the time domain. and used for the life cycle response analysis of a FOWT with 25 years of weather data.
All load components are synthesized at every instantaneous time step and converted to response-based stresses. This methodology efficiently and more accurately determines the stress distribution for different load cases which is useful for both new design and digital twin for integrity management to provide quick structural strength and fatigue damage assessment.
A Physical Model Approach to Mooring Forces and Motion Responses of a Closed Fish Tank Including Internal Free Water
Authors: Zhao Huaizhi , Dong Shuchuang , Zhou Jinxin , Li Qiao , Kitazawa Daisuke 
Published: September 2023

Abstract
In marine aquaculture farming, currently used flexible open-net cage systems face many problems and challenges, such as sea lice and other parasites, fish escape, and water pollution. The development of closed fish cage systems for fish farming has been driven by such problems. Closed fish cage systems interact with sea forces when subjected to waves and currents. The wave-induced motions of the closed fish cage would result in sloshing problems, i.e., internal fluid oscillations. Knowledge and experience on the internal sloshing issue are very limited, as closed fish cages are still a novel concept. In the present study, a series of physical model tests were performed to investigate the mooring forces and motion response characteristics of a circular closed fish cage. A decay test in calm water and regular wave experiments were performed for the closed fish cage in a wave basin. In addition, we set three different netting panels with different mesh sizes in the closed fish cage and investigated their inhibitory effects on internal sloshing flow under different configuration conditions. The results indicated that the general trend of maximum mooring forces was the same in both upstream and downstream mooring lines: first increased, then decreased, and finally increased again as the wave period continues to increase. The global motion responses of the fish cage system in the surge (pitch) directions exhibited similar trends with mooring forces. When the incident wave periods closed to the first mode of the sloshing period, the surge (pitch) response was almost zero. For internal water sloshing, it clearly showed that the second or higher harmonic components cannot be negligible, but had little effect on the global motion of the cage. Furthermore, the inhibition effect of the netting panels on the free water surface oscillation was confirmed, especially when the netting panel was horizontally placed on the inner free water surface, the most obvious inhibitory effect could be observed. Overall, these findings are expected to provide references for the design and operation of the closed fish cage system.
Numerical Modelling in the Development of the M4 Prototype for Albany, Western Australia
Authors: Kurniawan Adi , Wolgamot Hugh , Gaudin Christophe , Shearer Chris , Stansby Peter , Saunders Brad 
Published: September 2023

Abstract
A key step on the pathway to demonstrating wave energy converter (WEC) technology is ocean trials at a reduced scale. The Blue Economy Cooperative Research Centre and the Government of Western Australia (through the Department of Primary Industries and Regional Development) are funding the deployment of an M4 wave energy converter in King George Sound, Albany, Western Australia. The M4 WEC is an articulated device developed by M4 Wave Power Limited, which works best in waves comparable to the device’s length. At this location, strong easterly winds in the summer produce wind seas with wavelengths close to the length of the WEC, which is approximately 21 m. In order to determine the performance of the device at this site, a linear model of the M4 WEC has been developed using a generalised modes approach (not previously applied to the M4 WEC). Combined with local measurements of the wave field, this allows estimates of the power, motions, relative freeboard, etc. to be computed. The variant of M4 being analysed in this case is a ‘1-2-1’ version with a front triangular frame of 3 rigidly connected floats and one rear float on an articulated arm. This paper describes the model development, discusses reasons for choosing the scale of the device, the particular configuration, and the ongoing plan for the deployment.