bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the Coupled Dynamics of an Offshore Floating Multi-Purpose Platform: Part A — Rigid Body Analysis
Authors: Li L. , Collu M. , Ruzzo C. , Failla G. , Abhinav K. A. , Arena F. 
Published: November 2019

Abstract
A multi-purpose platform (MPP) is an offshore system designed to serve the purposes of more than one offshore industry. Indeed, over the past decades, a number of industries have expanded, or are expanding, from onshore to offshore locations (renewables, aquaculture, tourism, mineral extractions, etc.), and the research on these type of platform is increasing. In the present work, a MPP able to accommodate wind turbines, wave energy converters, and aquaculture systems are considered. This work presents the first part (Part A) of the analyses of the dynamics of the floating support structure for this MPP, focusing on the rigid body dynamic response, while its complementary hydroelastic analysis is presented in Part B (OMAE2019-96282).
The aim here is to assess the dynamic response of the platform with respect to the preliminary requirements imposed by the wind turbine, the aquaculture system, and the other ancillary systems. After describing the platform analyzed, and explaining the aero-hydro coupled model of dynamics approach adopted, two independent analyses are conducted, one using the SESAM package by DNV-GL, and another using ANSYS AQWA, in order to verify the results, in absence of experimental data. Considering a severe, but still operational, load case, the preliminary results seem to demonstrate that the chosen platform can satisfy the dynamics constraints imposed by the payload systems.
First in Place Replacement of a TLP Top Tendon Connector Flex Bearing
Authors: Otten Jeffrey D. , Kuriakose Vinu , Amini Shakib 
Published: November 2019

Abstract
Tension Leg Platform (TLP) tendons typically are installed for the life of the platform and incorporate elastomeric flex bearings. The Allegheny TLP, owned and operated by ENI Petroleum, was installed in Gulf of Mexico Green Canyon Block 254A, in 1999. It was designed for a service life of 20 years and currently ENI wants to extend the operating life of the platform. A baseline inspection showed significant degradation of the top tendon connector (TTC) flex bearing and it was concluded that the flex bearings needed to be replaced if the platform was to continue to operate safely.
SBM and BHGE came up with a solution for replacing the TTC including the flex bearing, which was accepted by ENI. This involved ballasting the TLP to reduce the tendon pretensions, installing a temporary buoyancy module, and using a hydraulic tool, first of its kind in the world, to take the load off of the old TTC and gradually release the tendon to free stand. The tool was then retrieved with the old TTC, onboard the installation vessel. A second identical tool with the new TTC was then lowered on to the porch and the tendon stretched to the lock-off position by the tool and locked in position with the new TTC. This was done on all six (6) tendons and the platform was de-ballasted to the original tendon pre-tensions. Development of the tendon de-tensioning tool required new designs, extensive shop testing, and planning.
The final offshore campaign took place during July 2018 and was completed in three (3) weeks. This represented a successful conclusion to a three (3) year effort. This paper highlights lessons learned in completing a complex first time ever project and makes recommendations for the design of future TLP’s.
Aeromechanical Analysis of Wind Turbines Using Non-Linear Harmonic Method
Authors: Win Naung Shine , Rahmati Mohammad , Farokhi Hamed 
Published: November 2019

Abstract
In this paper, aeromechanical analysis of wind turbines is presented. The distinctive feature of this paper is the use of frequency based non-linear harmonic method which is an efficient computational method to study unsteady periodic flow and aeroleasticity of turbomachinery applications, and extensive validation of the non-linear harmonic method against conventional time domain solution methods. This paper is an extension of the authors’ previous work which analysed the aerodynamics of the MEXICO (Model Rotor Experiments In Controlled Conditions) Experiment wind turbine. Aeromechanical analysis of the MEXICO-Experiment wind turbine as well as 1.5 MW wind turbine are conducted in this study. Both conventional time domain solution method and non-linear harmonic method are used, and compared to each other for validation and verification of the non-liner harmonic method. Using the same numerical set-up for each method demonstrates the differences and capabilities of each solution method, and their computational expenses. Finally, this paper concludes with how the aeromechanical analysis of large wind turbines can be performed effectively and efficiently using the non-linear harmonic method.
Advances in Riser Management Technology Enabling Improved Efficiency for Deepwater and Harsh Environment Drilling
Authors: Lang Donogh W. , Bohan Paul , Gomes Victor , Venero Germain , Corrignan Hugues 
Published: November 2019

Abstract
Despite the abrupt fall in crude oil prices since 2014, operators continue to explore for, and develop, oil and gas resources in some of the most challenging offshore environments. Exploration and development drilling is currently ongoing or planned in locations such as West of Shetland, offshore Eastern Canada, along Ireland’s Atlantic margin, in the South Atlantic Ocean and offshore South Africa. All these locations are characterized by the challenges of deepwater, powerful ocean currents and high seas.
With the lower oil price environment, carrying out drilling operations at these locations both safely and economically requires the adoption of new digital technologies and associated processes that maximize efficiency and reduce the cost of well programs. A significant aspect of this relates to planning and execution of operations involving the marine drilling riser, which can be a major contributor to non-productive time in deepwater and harsh environment locations. This paper describes a holistic approach to addressing this challenge, which covers every phase of riser operations for the drilling program, from pre-operations global riser analysis through to post-operations assessment.
The paper focuses on the technology that enables this holistic solution, with emphasis on the state-of-the-art riser management technology that is deployed on the drilling vessel. This uses an advanced finite element model of the riser, BOP stack, wellhead, conductor, casing and soil interaction as well as a detailed model of the riser tensioning system. The same model is used in both the pre-operations global drilling riser analysis phase and the operational drilling phase to ensure consistency.
Incorporation of the model provides the capability to perform forecast analysis on-board the rig, allowing offshore personnel to simulate a range of operations hours and days in advance using forecast metocean conditions, thereby assessing the feasibility of critical well construction operations before they commence. Capabilities for real-time monitoring of ongoing operations, fusing sensor data with the riser model, are also described. These provide calculation of live watch circles and operating envelopes for connected-mode operations, in addition to tracking of riser joint, wellhead, conductor and casing fatigue from both wave and VIV excitation. Additionally, calibration of soil models — often a critical input to wellhead fatigue analyses — can be performed.
Application of the technology is illustrated by means of a case study describing deployment on a record-breaking well in a harsh environment location. This demonstrated significant cost savings while simultaneously increasing safety and improving integrity assurance.
A Method to Calculate the Multi-Axial Fatigue of Subsea Rigid Jumper due to VIV
Authors: Kapoor Kunal , Liu Zhenhui , Ong Muk Chen 
Published: November 2019

Abstract
Prediction of vortex induced vibration (VIV) and estimation of fatigue damage for subsea multi planar structures exposed to significant current condition is an important topic for subsea engineering. Due to the multi-planar characteristics of structure, the VIV induced stress states of subsea jumper are normally with the combination of flexural and bending stresses. Consequently, the associated fatigue is a multi-axial fatigue problem. In this study a novel energy-critical plane method by Farahani [1][2] has been used for fatigue assessment instead of the traditional method with utilizing the stress range and SN curve, for example the 1st principle stress method as recommended by DNVGL-RP-F105 (2017) [3]. By using this method, the phase change of the stress from different modes is considered. A case study based on previous jumper experiments by ExxonMobil is included. Fatigue results have been compared with DNVGL-RP-F105 (2017) [3] approach. Advantages of energy-critical plane approach have been discussed. Phase change between flexural and torsional stresses has been successfully captured and its effect on fatigue damage has been presented. Additionally, some discussions have been performed with respect to the application of DNVGL-RP-F105 (2017) [3] to calculate the VIV fatigue to subsea rigid jumpers.
Analytical Methodology to Evaluate Flexible Risers Fatigue Lives at the Top Region
Authors: de Sousa Fernando Jorge Mendes , Queija de Siqueira Marcos , de Sousa José Renato Mendes , Campello George Carneiro 
Published: November 2019

Abstract
Traditionally, fatigue life calculations are very expensive in terms of time and computer resources. They are usually performed during riser design phases, when several lines with similar characteristics need to be analyzed. While operating, when problems are detected, fatigue analyses are also necessary to help to decide if any action is needed. In both situations, end fittings and bendstiffeners are usually the critical regions. Considering the high number of flexible risers installed in Brazil and the structural complexity of this kind of structure, a robust and fast methodology to evaluate the fatigue life of flexible risers becomes attractive. In this way, this paper proposes a analytical/numerical methodology to evaluate the fatigue life at the top region of flexible pipes. Using the top imposed motions and taking into account the properties of all structures in the riser, it is possible to evaluate tension analytically. Combining tension and the rotations imposed at the top of the riser, curvatures are determined, and stresses can be calculated. Finally, SN curves and the Miner’s rule for damage accumulation allow the estimation of fatigue life. The obtained results indicate that the proposed methodology is conservative when compared to traditional ones. Also, it is very fast, allowing the fatigue life estimation in minutes.
Current Induced Drag Forces on Cultivated Sugar Kelp
Authors: Endresen Per Christian , Norvik Carina , Kristiansen David , Birkevold Jens , Volent Zsolt 
Published: November 2019

Abstract
To obtain more knowledge of current induced drag forces on sugar kelp, towing tests with ropes containing cultivated sugar kelp was conducted. As freshwater may damage the kelp and cause changes in its mechanical response, tests were performed in a test facility containing seawater. A special purpose test rig was constructed for towing of ropes at different constant velocities through the water, thus simulating water current. The ropes were mounted horizontally and perpendicular to the towing direction. Several ropes, all 3 meters long, with either a medium level or high level of growth, were tested individually. The ropes with sugar kelp were collected from a seaweed farm prior to the experiments and tested with the kelp still attached to the ropes on which they were grown. The total drag forces on the ropes were measured along with the towing velocity. Based on the results from the experiments relations between drag forces, measured size, weight of the kelp and current velocity were found. The results also show signs of reconfiguration of the plants, i.e. adaption to the current flow to reduce the experienced loads. As a result, a power function with an exponent smaller than 2 can be used for modelling of the drag forces. The drag force seems to go towards a value proportional to the velocity squared for higher velocities, indicating that the plants might no longer be able to reduce the forces through reconfiguration. Results from this study expand the knowledge of drag forces on ropes with cultivated sugar kelp and may be implemented into a suitable numerical code for estimation of hydrodynamic loads on seaweed farms.
Emerging Technology in Fitness-for-Service Assessment of Crack-Like Flaws
Authors: Anderson Ted L. 
Published: November 2019

Abstract
This paper describes several recent advances in crack assessment technology that have been or will be incorporated into the API 579 fitness-for-service standard. Four technology areas are addressed herein:
• Stress intensity factor solutions. The 2016 edition of API 579 contains an extensive library of stress intensity solutions inferred from 3D finite element analysis.
• A new equation for fitting elastic-plastic J solutions. A parametric equation that captures the elastic, fully-plastic and contained-yielding regimes of deformation provides an alternative definition of reference stress in the failure assessment diagram (FAD) method.
• An enhanced constraint adjustment. A future edition of API 579 will include an improved version of the Wallin methodology for shifting the Master Curve reference temperature to account for constraint effects.
• A procedure to account for non-ideal crack profiles. Most crack assessment methods assume an idealized flaw shape such as semi-elliptical, but many real-world flaws have complex shapes.
Flow Past a Forced Oscillating Cylinder: A Three-Dimensional Numerical Study
Authors: Ping Huan , Bao Yan , Zhou Dai , Han Zhaolong 
Published: November 2019

Abstract
In this paper, we conducted a three-dimensional investigation of flow past a cylinder undergoing forced oscillation. The flow configuration is similar to the work of Blackburn & Henderson (1999) [1], in which Reynolds number equals to 500 and a fixed motion amplitude of A/D = 0.25. The oscillation frequencies are varied in the range near to the natural shedding frequency of a stationary cylinder. The flow dynamics are governed by Navier-Stokes equations and the solutions are obtained by employing high-order spectral/hp element method. It is found that the flow dynamics are significantly distinguished from the study of two-dimensional flow by Blackburn & Henderson (1999) [1]. The values of hydrodynamic forces are smaller compared to that in the two-dimensional study. However, lock-in boundary we identified is broader. In addition, a different type of hysteresis loop of energy transfer coefficient is obtained.
On GIS Based Facility Scale and Selection of Suitable Site of Floating Medical Support System on Big Disaster
Authors: Eto Hiroaki , Togawa Sachio , Yamamoto Morikazu , Miyasawa Shintaro , Yamaguchi Junko , Ikoma Tomoki , Aida Yasuhiro , Masuda Koichi , Shimomoto Sena , Kitabatake Yuichi 
Published: November 2019

Abstract
In 2011, Japan experienced a major catastrophe: The Great East Japan Earthquake and subsequent tsunami. After the tsunami struck, overland transport routes were cut off, and consequently, emergency supplies and people requiring medical attention could not be transported very efficiently. Many hospitals and other emergency facilities were destroyed or were operating with reduced capabilities during this period, meaning victims could not receive treatment within a reasonable timeframe. Therefore, we need to consider emergency facilities, particularly for medical support, which are resilient and versatile for use in such situations. Floating bases for disaster relief and support ships are already available for deployment along coastal regions or on rivers near affected areas. A medical support floating base has also been proposed, which is called the Medi-float hereafter, in preparation for the anticipated Tokyo Inland Earthquake. And it is determined that the primary function of this Medi-float should be as a dialysis treatment center during normal operation and primarily for the treatment of crush syndrome patients during a disaster. But the original proposal was deemed inadequate in terms of facility scale and selection of the suitable site of Medi-float. Therefore, in this research aiming at realization of Medi-float, firstly the number of people who develop crush syndrome in the target area is estimated by GIS based on the damage prediction of the huge earthquake striking Tokyo and the risk of building collapse. Based on the distribution of dialysis treatment facilities and data such as road network data in Tokyo, Voronoi diagrams were created using GIS. And facility scale required for Medi-float and suitable installed site were examined by the distribution of crushed syndrome patients obtained by analysis and Voronoi diagram.
Numerical Simulations of Riser Gas Behavior in Non-Aqueous Muds Using a Modified Drift Flux Model
Authors: Nwaka Nnamdi , Chen Yuanhang 
Published: November 2019

Abstract
Real-time prediction of riser gas behavior is of great importance in well control. Single bubble models have, thus far, been used to describe gas-in-riser events and define riser equilibrium. These models have however not considered the transient nature of desorption of gas influx from non-aqueous fluids (NAFs) during migration or circulation in a riser. This paper uses a modified drift-flux model (DFM) to more properly describe gas-in-riser events by incorporating time-dependent mass transfer processes in NAFs.
In this paper, we modified the DFM to account for the gas-liquid mass transfer due to the time dependent desorption of the gas phase. The advection upstream splitting model (AUSMV) hybrid scheme was used to solve the model. The time dependent mass transfer is calculated using a kinetic model developed based on recent experimental data.
The capability of this model to improve riser gas management is demonstrated using a case study and the simulations are compared to when mass transfer between gas influx and NAF is not considered. Results also show that the severity of unloading and depth of the riser equilibrium can be underestimated if a time dependent desorption is not considered.
The concept of riser equilibrium has been, thus far, developed without due consideration of mass transport of gas phase in the mud. This paper factors in the time-dependent desorption of the gas phase in the mud for a more realistic prediction of riser gas unloading events.
Characteristics of Transforming Waves Breaking Over a Fringing Reef
Authors: Gong Fuxian , Dhanak Manhar R. 
Published: November 2019

Abstract
Direct numerical simulation (DNS), based on solution of the Navier Stokes equations, is used to study the characteristics of the transformation of monochromatic waves over a simplified fringing reef, including wave shoaling, and wave breaking that occurs under certain circumstances. The reef geometry involves a sloped plane beach extended with a simple submerged horizontal reef flat. The characteristics are studied for several case studies involving a selection of submergence depths on the reef flat and for a range of incident wave conditions, corresponding to nonbreaking, a spilling breaker and a plunging breaker, are considered. The results are compared with those of laboratory experiments (Kouvaras and Dhanak, 2018). Consistent with other studies, generation of harmonics of the fundamental wave frequency is found to accompany the wave transformation over the reef and the process of transfer of energy through wave breaking. The energy flux decreases dramatically in the onshore direction when the waves break. The more severe the wave breaking process, the greater the decrease in energy flux, particularly in the wave shoaling process. Most of the wave energy is carried by the first harmonic throughout its passage over the fringing reef. In nonbreaking waves, the energy gradually transfers from the first harmonic to the second harmonic due to bottom effects in terms of flat wave troughs and secondary waves. The further the distance away from the fore edge of the reef, the larger the percentage of the transmission, resulting in a single dominant harmonic frequency at the end of the wave surfing zone. For breaking waves, the energy carried by the first harmonic gradually decreases in the onshore direction. Energy transmission between harmonics is not as efficient as nonbreaking waves, while wave dissipation is significant in the wave breaking process.
Learning From Dynamic Positioning Events
Authors: Kvitrud Arne 
Published: November 2019

Abstract
Sixteen loss of position incidents on fourteen units are reported to us from the petroleum activity on the Norwegian continental shelf, from 2014 to 2018. The incidents had a mixture of severity, with pollution of 360m3 mud, damage to drilling and production equipment, falling objects and three autolifts of bridges as the most severe consequences. The incidents are described briefly and the most common causes of the events are found. The cases are discussed in view of several approaches. The barrier concept, and modifications of previous established barrier functions and barrier elements are discussed. I discuss the man-technology-organisation examinations in the investigations. Further the application of the single failure analysis philosophy is reviewed, and I discuss limitations to the method based on our cases. Our cases are compared with previous learning from incidents on shuttle tankers. A discussion is done on the slow reactions to changes in the weather conditions. In the last section I discuss needs for improvement.
Improvement of the Method for Calculating Downhole Weight on Bit and its Application in Autodriller Systems
Authors: Wu Zebing , Guo Longlong , Zhang Shuai , Wu Yuanping , Lv Lantao , Wang Wenjuan , Pan Yujie , Wang Yongyong , Mokhtari Adnane El 
Published: November 2019

Abstract
The accuracy of downhole weight on bit (DWOB) is one of the most important factors in the improvement of drilling efficiency, especially in horizontal well drilling. This paper introduced an analytical model and developed a corresponding program to calculate DWOB using drilling data on the surface. A well with field data measured was utilized to verify the model. The results indicate that the calculated friction factors are reasonable, and the DWOB calculated using the analytical model is consistent with those measured by the measurement tool. To satisfy the requirement of real-time drilling monitoring, a least square fitting (LSF) model for the relationship between the DWOB and surface weight on bit (SWOB) measured by deadline sensor on the surface was established to improve the calculation speed. Compared to the analytical method, the LSF model features much faster calculation speed, and the DWOB predicted by LSF model shows much better agreement with the measured DWOB. In addition, the influence of friction factors and standpipe pressure on the coefficients of LSF model was analyzed. The method and calculation technique proposed have applications potential, such as integration with present autodriller systems, post-drilling analysis, drilling operation monitoring, drilling optimization and automation.