bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wave-Induced Loads Acting on Monopile Configurations Considering Wake Effects
Authors: Thome Michael , el Moctar Ould , Schellin Thomas 
Published: October 2022

Abstract
This comparative study investigated wave-induced impact loads acting on two aligned cylinders placed in a wave canal. Initially, loads acting on a single cylinder in a focused wave were experimentally measured to validate the associated numerical predictions. Subsequently, four scenarios were considered, of which the first scenario dealt with the direct calculation of loads on a single cylinder, albeit with cylinders of three different diameters. The second scenario considered two cylinders of the same diameter, which were implemented in tandem. The loads acting on the upstream and downstream cylinders were calculated directly considering the wake effects on the downstream cylinder. For the third scenario, both cylinders were removed, and the loads on the downstream cylinder were determined using the Morison equation. In the fourth scenario, only the downstream cylinder was removed to examine whether loads on the downstream cylinder can be approximated using the Morison equation. Employing an unsteady Reynolds-averaged Navier-Stokes (URANS) equations solver coupled with the volume of fluid (VoF) method, flow velocities were computed at different height positions corresponding to the location of the missing downstream cylinder in scenarios three and four, and these velocities were used in the Morison equation. Flow accelerations were derived from flow velocities using the central difference scheme. These load predictions enabled finding out how well the Morison equation is able to provide useful load predictions even in the presence of wake effects. Wake effects of the front cylinder on the loads acting on the rear cylinder were computed and analyzed. It turned out that maximum impact loads were favorably predicted using the Morison equation, even for the scenario that considered wake effects. However, the timely evolution of these loads after impact differed from comparable measurements.
Hydrodynamic and Mechanic Response of a Floating Flexible Ice Floe in Regular Waves With the ICFD Method
Authors: Behnen Jonas , von Bock und Polach Rüdiger u. Franz , Klein Marco , Ehlers Sören 
Published: October 2022

Abstract
Climate change provides for a stronger wave climate and the open water area in this region will increase. The increase in open water area allows for an increase in higher energy surface waves than previously. In addition, human activities are much more complex in this zone, called Marginal Ice Zone, compared to the open ocean, so that there is an increased research interest in the physical processes of wave-ice interaction and the resulting statements on the influence on maritime technology. This work deals with the development of an efficient simulation environment for the 2D wave-ice interaction on the finite platform LS-DYNA. The numerical model based on the coupled ICFD and implicit structural solvers of LS-DYNA. The motion behavior and the mechanical behavior of the ice floe due to the interaction with different waves are investigated. The stronger wave climate in the Marginal Ice Zone intensifies, making the waves more energetic and increasing the wave steepness. The results of the simulation clearly show that larger wave steepnesses have a large influence on the mechanical stress in the ice floe and the deflection increases. These mechanical stresses lead in the critical cases to a fracture of the ice floe into several smaller ice floes. Consideration of the ratio of ice floe length to wave length showed that the smaller the ratio, the larger the heave and surge movements of the ice floe induced by the waves.
Off-Bottom Plug Placement: On the Effects of Pulling Out of the Hole
Authors: Ghazal Abdallah , Karimfazli Ida 
Published: October 2022

Abstract
Several cement plugs are often placed along cased oil and gas wells, commonly using the balanced-plug technique, to ensure proper abandonment. The placement process starts with the injection of cement slurry into wells that are otherwise filled with lighter wellbore fluids. The injector is pulled out of the hole when the cement slurry is levelled in the injection tube and the annular space between the injector and casing walls (from hereon referred to as POOH). Successful placement is achieved if the plug remains in place after the POOH. In our previous works, we investigated the hydrodynamics of the early stages of the balanced-plug method and provided a mechanistic description of the events that would lead to the accumulation of the injected fluid. In this work, we focus on the hydrodynamics of the final stage of the balanced-plug method. We study the impact of POOH on the lower interface of the injected cement layer. We develop a two-dimensional (2D) model that is representative of the process and conduct numerical simulations, using OpenFOAM, to explore the deformation of the lower interface of the cement plug at different POOH velocities and for different distances between the injector tip and the lower interface of the cement plug.
We show that the injector pullout creates vortices at the injector tip, leaving a trail of vortices within the viscoplastic layer as the injector is pulled away from the interface. Our preliminary results suggest that the interface evolves approximately independently of the injector pullout when the initial distance between the injector and the bottom interface of the cement plug is sufficiently large. Here, the development of instabilities at the interface is reminiscent of the Rayleigh-Taylor instability (RTI) irrespective of the pullout velocity. We show, however, that the injector pullout promotes the mixing of fluids when the interface is close to the injector initially. Reduced POOH velocity appears to enhance the mixing close to the interface.
A Fast and Transparent Method for Setting Powering Margins in Ship Design
Authors: Liu Shukui , Shang Baoguo , Chen Haoliang , Papanikolaou Apostolos 
Published: October 2022

Abstract
The selection of powering margins is a paramount subject in ship design to assure the satisfactory speed performance in ship operation. In this work, the influence of wind and wave on ship resistance is calculated using the methods recommended by ITTC [16]. The influence of fouling on resistance is predicted by the method of Granville [18,19], while the influence of fouling on propeller performance is predicted by the method discussed at ITTC [20]. The seaway conditions are derived by onboard monitored data while the hull and propeller are assumed to be in line with practical observations. All the implemented methods have strong background in theoretical and experimental studies, and are easy-to-use and fast in execution. A case study is presented to demonstrate the methodology. This work is expected to support ship owners, operators, and designers in determining the powering margins in the frame of preliminary ship design.
Numerical Modelling of Wave-Induced Liquefaction Around Pipelines and Offshore Cables
Authors: Kirca V. S. Ozgur , Yilmaz S. Utku , Sumer B. Mutlu , Shanmugasundaram Ranjith Khumar , Rusche Henrik , Windt Christian , Goseberg Nils 
Published: October 2022

Abstract
Submarine pipelines and offshore cables are critical infrastructures for the offshore energy industry. Marine structures like pipelines and offshore cables buried in loose finegrained seabed soil, such as silt or fine sand, maybe under the threat of wave-induced liquefaction. Such failures (flotation or sinking of structures due to liquefaction) have been reported widely in the literature. Observations show that the presence of pipelines/cables can enhance the wave-induced liquefaction susceptibility. This paper presents early results of a numerical modeling study in which the liquefaction potential around a pipeline/cable buried in seabed soil is investigated. A numerical model being developed in the OpenFOAM CFD toolbox under the NuLIMAS (Numerical Modelling of Liquefaction Around Marine Structures) Project is utilized. The results show that the model is capable of simulating the pore pressure buildup around pipelines (or cables), both in near or far field. Additionally, it is shown that different wall boundary conditions of pipelines/cables (i.e. smooth or rough) can be modeled in the numerical model, which is a convenient feature of the model for utilization in practical applications.
Evaluation and Understanding the Potential of Enhanced Oil Recovery for a Candidate Offshore Sandstone Field
Authors: Qi Chuangchuang , Rabbani Aneesa Ijaz , Suboyin Abhijith , Ponnambathayil Jassim Abubacker , Rahman Md Motiur , Haroun Mohamed , Ma Qisheng , Gibrata Muhammad A. , Rouis Lamia , Djanuar Yanfidra 
Published: October 2022

Abstract
The aim of this investigation is to develop a comprehensive understanding of an enhanced oil recovery (EOR) candidate reservoir based in an unconventional sandstone dominated environment. The unique geology, owing to its proximity to an inland, endorheic basin, alongside its complex stratigraphic geometry incorporating extensive folding and faulting as well as a laterally extensive unconformity. The study leans heavily on the forefront of reservoir characterizations.
Reservoir characterization is crucial in providing an outline of the sub-surface and helps visualize the hydrocarbon system in-place. Our study area is the deeper consolidated units. This section was analyzed in detail to understand the petrophysical and fluid properties. The properties of the rock formation(s) of interest were identified from mineralogical content based on XRD analysis and SEM analysis to develop an interlink between the results. A compilation of the results plays a key role in determining reservoir quality and fluid properties which heavily influences important variables such as porosity, permeability, capillary pressure, relative permeability, wettability, interfacial tension, and fluid compositions. The clay mineralogy affects the penetration rate and the diagenetic overprint either enhances or deliberates fluid flow.
The novelty of this integrated study lays the foundation for a thorough and bespoke screening EOR study, which is currently under development for an offshore candidate field. Preliminary screenings were also conducted through core flooding with representative outcrops. An understanding of the integration of the various reservoirs and fluid properties is essential in determining the characteristics of the entirety of the candidate reservoir. Incorporating these complex zones in an integrated reservoir characterization study is fundamental in achieving successful EOR deployment and optimizes oil production.
A Joint-Industry Effort to Develop and Verify CFD Modeling Practice for Predicting Hydrodynamic Coefficients of Risers: Part II – Staggered Buoyancy Module and Straked Riser
Authors: Jang Hyunchul , Agrawal Madhusuden , Huang Zhenjia (Jerry) , Jiang Fengjian , Wu Jie , Lie Halvor , Croonenborghs Eloïse 
Published: October 2022

Abstract
Hydrodynamic force coefficients are important parameters in the design and assessment of marine risers. The hydrodynamic coefficients are widely used for assessing marine riser responses due to floater motion excitation and vortex-induced vibrations (VIV). Traditionally, the hydrodynamic coefficients have been obtained from physical model tests on short rigid riser sections. Recently, the offshore industry has started to use Computational Fluid Dynamics (CFD) analysis for predicting the hydrodynamic coefficients, due to the recent advancement of CFD software and high-performance computing capabilities. However, a reliable CFD modeling practice is required for CFD analysis to be a more widely accepted prediction tool in the industry. A joint industry effort has been initiated for developing and verifying a reliable CFD modeling practice through a working group of the Reproducible Offshore CFD JIP. Within the working group, a CFD modeling practice document was written based on existing practices already validated with model test data and verified by blind validations with three CFD practitioners. The first year work focused on a bare riser with circular cross-section and has been published in OMAE 2021.
This paper presents the working group’s second-year verification activities for a staggered buoyancy module and a straked riser. The verification work covers three numerical test problems: 1) stationary riser in steady current, 2) riser under forced-oscillation in calm water, 3) riser under forced-oscillation in steady current. In the stationary riser simulation, drag coefficient and lift coefficient from verifiers are compared. In the forced-oscillation simulation in calm water, the fully-submerged riser section oscillates with a sinusoidal motion, and damping and added-mass coefficients are compared. In the forced-oscillation simulation in steady current, where the riser oscillates in either inline or perpendicular direction to the steady current, lift coefficient and added mass coefficient are compared. By following the modeling practice, the CFD predictions are consistent with each other and close to the model test data for the majority of the test cases.
Data Assimilation-Based Real-Time Estimation of Downhole Gas Influx Rate and Void Fraction Distribution in a Drilling Riser
Authors: Wei Chen , Chen Yuanhang 
Published: October 2022

Abstract
The ability to perform an accurate estimation of the downhole influx rate and the distribution of the invaded formation gas is of great importance for the modeling of a riser gas event, particularly when the gas kick is to be circulated out through the riser using Managed Pressure Drilling (MPD) systems. Due to the lack of knowledge of the formation pore pressure and the great complexity of wellbore two-phase flow, the influx rate of gas entering the riser is difficult to estimate or direct measure, bringing great uncertainties in the current methods of riser gas modeling. An Extended Kalman Filter (EKF) is used as a Data Assimilation (DA) method for real-time estimation of riser gas influx rate and the enhanced accuracy of the existing physics-based flow models.
Data from a set of full-scale experiments is introduced in this study. A riser gas event in a Water-Based Mud (WBM) system is replicated in the experiments by injecting gas from the bottom of an experimental wellbore. The real-time measurement data, including the surface backpressure, the pressure at the subsea blowout preventer (SSBOP) level, and the liquid outflow rate, are used to estimate the rate of gas entering the riser using the EKF. An online calibrated Drift Flux Model (DFM) implemented with DA is used to estimate the distributed flow parameters, including the profiles of gas void fractions. The gas injection rate measured by a Daniel flowmeter and the downhole Distributed Acoustic Sensing (DAS) data from the full-scale experiments were used to validate the estimation results of the proposed method. Results show satisfying agreement between the estimation and the measurement data.
The benefits of this work are seen in the estimation of the parameters that are difficult to directly measure or control and in the maximized usage of measurement data of different types, realizing the more accurate prediction of gas influx behaviors in the riser. The inclusions of the model online calibration with coefficients adaptively tuned help to further improve the performance of the existing two-phase flow models and help the design of riser gas management strategies.
Influence of Pigging Velocity on the Wax Removal Process in Subsea Pipelines
Authors: Zhang Xun , Huang Qiyu , Chen Wei 
Published: October 2022

Abstract
Wax deposition has been a significant concern in flow assurance. Mechanical pigging is the most common technique used to remediate wax deposition in subsea pipelines. Although researchers have revealed the wax removal process of pipe pigs, it is still unclear whether the pipe pig speed affects the pigging process. Due to a lack of understanding of the wax removal process, the field pigging operation is mainly reliant on empirical rules, resulting in frequent blockage accidents. In this work, the effect of pipe pig speed on the pigging process of cup and disk pigs was investigated using the in-house pigging facility. The experimental results show that the pigging process of both pipe pigs at high and low speeds can be divided into four parts. However, the wax breaking force (WBF) is approximately 2–3 times greater at high speed than at low speed. Also, the WBF of the disk pig is higher compared to the cup pig under the same pigging conditions. The mechanism behind this phenomenon is because of the rheological features of wax deposits. Since the wax deposit exhibits rheomalaxis elasto-viscoplasticity, it is exposed to a larger shear rate at high pipe pig speed, which leads to increased dynamic yield stress of the wax deposit. Furthermore, the difference in WBF between cup pigs and disk pigs results from the geometric characteristics of the pipe pigs. This work can serve as a qualitative guide for on-site pigging operations of subsea pipelines.
The Role of Particle Size Distribution for Fluid Loss Materials on Formation of Filter-Cakes and Avoiding Formation Damage
Authors: Klungtvedt Karl Ronny , Saasen Arild 
Published: October 2022

Abstract
Numerous studies have shown that careful particle size selection is the main parameter for reducing fluid loss when drilling permeable or fractured formations. The methods are generally built around either the D50 or D90 values of the particles in the fluid as a relative size to the pore openings of the formation, to minimise fluid loss.
A series of studies were conducted to measure fluid loss, solids invasion and formation damage. Further, numerical models were developed to describe fluid loss and the build-up of internal- and external filter-cakes with corresponding permeabilities.
It was discovered that different particle size methods should be used for optimising a fluid with regards to reducing fluid loss during the drilling of upper sections of a well than when a drilling fluid is optimized for reservoir drilling and preventing formation damage.
It was concluded that conventional particle size methods were found to be adequate for designing a fluid for wellbore stabilisation purposes. This led to higher solids invasion and a more impermeable internal filter-cake. However, for optimisation of reservoir drilling fluids, a different particle size selection method was found to be more useful to prevent reservoir formation damage. This method involves selecting particles that are resistant towards shear-degradation and with a D90 particle size ⪞ 3/2 the pore size of the formation.
On the Erasing of the Cyclic Preloading by Monotonic Deformations in Granular Soils
Authors: Wappler Andreas , Knittel Lukas , Niemunis Andrzej , Stutz Hans Henning 
Published: October 2022

Abstract
For the design and construction of Offshore Wind Energy Turbines (OWT), it is essential to predict deformations in the subsoil. Wind and waves cause a high-cycle loading on these structures. To ensure their servicability, reliable soil models for predicitions of cumulative displacement over the expected OWT lifetime are needed. In this work, the explicit constitutive High-Cycle Accumulation Model (HCA-Model) by Niemunis et al. [1] has been modified to account for the influence of large monotonic strains on the rate of subsequent cyclic accumulation. In this research project, 21 drained cyclic triaxial tests on saturated, cylindrical Karlsruhe fine sand samples were performed. The packages of cycles were applied on the specimens one after another. Between the packages, the average stress state was monotonically changed. To examine the reduction of the so called cyclic preloading, the tests were analysed regarding the accumulated strain throughout the packages of cycles in each test and the monotonic strain resulting from the change of the average stress state between the packages. In addition, finite-element calculations on an exemplary shallow foundation of an OWT were performed. Two packages of cycles with modification of the cyclic preloading were studied. The reduction of the cyclic preloading was evident.
Global Optimization Workflow for Offshore Drilling Rate of Penetration With Dynamic Drilling Log Data
Authors: Cao Jie , Ren Hui , Sui Dan 
Published: October 2022

Abstract
The prediction and optimization of drilling rate of penetration (ROP) are among the most effective approaches in improving drilling efficiency. To achieve that, it calls for a well-established prediction model and a well-defined optimization methodology. With the advancement in large dataset acquisition and computational efficient machine learning methods, data-driven ROP prediction has superiority over classical physical models. Furthermore, when the ROP prediction model is trained and validated, it can be used to optimize the controllable parameters, preferably globally, given objective functions and proper constraints. The global optimization of drilling ROP is desirable in the design phase, such that the controllable parameters can be optimized for the whole planned well depth. This provides an optimum plan pushing the limit of drilling efficiency and provides valuable controlling strategies that guide the drilling operations.
The main object of this research is to investigate the global optimization workflow for ROP using prediction models based on machine learning methods. We first present an automated data processing method, dealing with and taking advantage of the variety and a vast amount of the drilling dataset. Then, the deep neural network (DNN) model for ROP predictions is validated and tested. In the trained predictive model, there are three controllable parameters, weight on bit (WOB), drilling string revolution speed (RPM), and drilling fluid flow rates (Q). Next, we choose the genetic algorithm (GA) to search the global optimal parameter combination in the control parameters space. The optimization workflow can be applied for the whole well depth, various segments of depth intervals, and different formation layers, resulting in a combination of controllable parameters for the entire well, for every section of given depth intervals, and for each formation layer, respectively. In summary, the global optimization workflow incorporates end-to-end data processing and promotes improved drilling efficiency. The global optimized results push the limit of drilling efficiency and provide valuable post-drilling analysis and offset drilling design recommendations. However, the extreme optimum results may not be reached in field practice, as more constraints such as formation information need to be applied to make the operation realistic.
A Journey From Daily Engineering to Machine Learning, Application to Rigid Pipeline Reel-Laying
Authors: Capelle François-Guillaume , Durand-Gasselin Jonas , Giry Eric , Laye Amandine 
Published: October 2022

Abstract
Digitalisation of engineering analyses has seen a change from limited and time-consuming individual tasks into an organised exercise of automated calculations, sensitivity studies and standardised reporting of results. However, the digitalisation process is not a mere automatisation of the computational activities reducing Engineers to simple “button pushers” but it enables an innovative approach of the design activities that contributes to rise their level of expertise.
An example of implementation of the digitalisation process for the design of subsea pipelines is presented here. The objective is to reduce time spent by Engineers on low value activities and to support comparison, interpolation and presentation of the results to get optimised solutions more efficiently.