bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Fuzzy Logic and Expert Elicitation for Quantitative Offshore Well Integrity Data Collection
Authors: Abreu Danilo Taverna Martins Pereira de , Rocha dos Santos Joaquim , Morais Carlos Henrique Bittencourt , Martins Marcelo Ramos , Colombo Danilo 
Published: December 2020

Abstract
The risk of uncontrolled hydrocarbon releases in oil & gas wells is mitigated through well barrier elements (such as casings, Xmas trees and packers), which are physical components capable of holding the undesired flow of reservoir fluids. Along with operational and management measures, the well barrier elements ensure the well integrity. Typically, these elements compose well barrier sets and, at least, two tested well barrier sets should be in place during the entire life cycle. Currently, limited quantitative failure data regarding well barrier elements exists, and this fact limits a migration from the qualitative approach currently in place to a quantitative one.
There are several possible sources of quantitative failure data, such as analysis of historical data, manufacturer’s data, use of commercial databases, and expert elicitation. This latter approach is based on the operational experience of experts and is adequate when there are few existing data from the other sources and limited resources (including time) to collect the data empirically.
This paper presents the application of an expert elicitation methodology for collection of well integrity failure data. This methodology is based on the application of fuzzy set theory and allows aggregating the opinions of different experts within a group in an attempt to reach consensus.
The results include a sample of the obtained data and comparison with the results from commercial databases. The collected data serves as input for reliability analysis models, which allow predicting the probability of failure/availability of well barriers along the life cycle.
A Study on the Difference in Wave Statistics Based on Storm Model for the Ship Structural Assessment
Authors: De Gracia Luis , Wang Helong , Mao Wengang , Osawa Naoki 
Published: December 2020

Abstract
Ocean-going vessels are under the continuous influence on the effect of the weather, e.g. wind, waves, ocean currents. Since the weather conditions are random in nature, there are situations where the shipmaster changes the ship speed or/and heading of the original sailing path to avoid harsh weather conditions according to his judgment, experience and/or using voyage optimization systems (e.g. weather routing systems). However, ship operators hardly prioritize the ship fatigue routing in their operations. It is preferable to consider the effect of different wave environment due to ship operation in the design process to make a more rational ship design of the structural members.
In this study, sailing paths are planned, adopting voyage optimization in order to reduce the probability of encountering severe sea conditions and the minimization of the fatigue accumulation in ship structures. Short-sea sequences are generated by a statistical wave storm model. The storm profiles are determined by using the cumulative frequency of short-seas which are experienced in the different voyages optimized by the algorithm. The influence of the difference in short-seas encountered by the target ship following the optimized voyages on the cumulative damage is demonstrated by a container vessel, which also considers a weather routing system in her operations. Full-scale measurement data for two years’ voyages are considered for the verification. The benefits of using voyages optimization systems focus on reducing fatigue damage to mitigate the risk of structural failure is discussed.
Numerical Model Development of a Variable-Geometry Attenuator Wave Energy Converter
Authors: Pardonner Davy , Tom Nathan , Guo Yi 
Published: December 2020

Abstract
Because the wave energy industry is still in its infancy, an optimal design for wave energy converters (WECs) has yet to be established; more work is needed to explore various cost-reduction pathways. The primary cost-reduction pathway considered for this work is the optimization of the geometric profile on an attenuator WEC to maximize power production while, at the same time, minimizing capital expenditures through the use of variable-geometry modules. In this investigation, the variable-geometry modules consist of inflatable bags placed on either side of a base central steel cylinder that would be inflated in low-moderate sea states to maximize power capture and then deflated in moderate-extreme sea states to minimize wave loading. The numerical model and simulation of the attenuator WEC were developed and completed using WEC-Sim, which is an open-source code that is appropriate for use in evaluating the dynamic response of the different WEC models in operational seas. The power production estimates were obtained from the Wave Energy Prize (WEP) sea states, which are representative of U. S. deployment sites, to calculate the average climate capture width that is used in the WEP ACE calculation. Preliminary capital expenditure costs were obtained assuming the base central steel cylinder mass was equal to the fluid displaced mass, minus the mass of the variable-geometry bags. The additional weight required to offset the additional buoyancy from the variable-geometry bags was assumed to come from the addition of seawater ballast. The variable-geometry attenuator model was found to have a similar power capture efficiency as a fixed-body model, but is expected to have a lower characteristic capital expenditure given its more streamlined profile, which demonstrates that variable-geometry modules may provide a realistic cost-reduction pathway to help design a more cost-competitive WEC.
Field Trials of Suction-Assisted Installation of Circular Steel Pipe Cofferdam in Silty Sand
Authors: Kim Jae-Hyun , Xin Zhenhua , Lee Ju-Hyung 
Published: December 2020

Abstract
The cofferdam is the temporary barrier to stop the flow of water from a construction site work such as a support column foundation at a river or offshore. It allows for working in the dry condition when the construction is done adjacent or within the waters. However, it is a major cause of delays and increased construction costs because additional works are required to stop the water flow. Recently, in order to overcome the limitations of the conventional cofferdam methods such as sheet pile or caisson tube cofferdams, a large-diameter steel pipe cofferdam method has been proposed which can be installed quickly using suction installation method. The steel pipe cofferdam method is characterized in that the top-lid of the steel pipe is located above the sea level in order to use it as a water barrier, unlike conventional suction buckets where the whole structures are submerged. In this study, the circular steel pipe cofferdam with a 5 m inner diameter was fabricated and the installation tests were conducted on silty sand at the Saemaguem test site. During the experiment, variations of suction pressure and inclination of the steel pipe cofferdam were measured and post-analyzed. This study verified the new steel pipe cofferdam method and confirmed that the suction installation method can be successfully used for various purposes on the offshore structures.
Research on the Static and Dynamics Characteristics of Soft Yoke Mooring System Based on Multi-Rigid Body Interaction
Authors: Wang Hongwei , Zhang Zizhao , Ma Gang , Ma Rongtai , Yang Jie 
Published: December 2020

Abstract
Select the common mooring system-soft yoke mooring system as the research object. The soft yoke mooring system is regarded as a structure composed of multiple rigid bodies, and the theoretical analysis of multi-body dynamics is used to discuss the interaction of multi-rigid bodies.
The classical HYSY113 FPSO is selected as an example, for the soft yoke mooring system, the stiffness characteristics and static restoring force curved compared with those of software OrcaFlex, and they are in good agreement, which verify the reliability of the formula derived, and it is a prerequisite for the accurate simulations in further steps. Coupled analysis to the whole system in time domain is also carried out both in OrcaFlex and AQWA, and the representative response of the FPSO under different environmental conditions is compared, the results are consistent well with each other. It is a good reference for the future study in this field. Good static characteristics are a prerequisite for accurate analysis of time-domain motion. By comparing the results in the time domain, it is found that under the same working conditions, the analysis results calculated by different commercial software (AQWA and OrcaFlex) may be different. We need to perform design analysis based on the characteristics of the software.
The Role of Engineering Critical Assessment in the Life Extension of Risers Connected to Floating Systems
Authors: Mekha Basim , Gordon Robin 
Published: December 2020

Abstract
As many offshore production systems approach the end of their original Design Life, Operators are faced with the choice of either decommissioning or demonstrating that the original Design Life can be extended (Life Extension). Life extension requires the Operator to perform detailed engineering analyses to verify that the system can be operated safely over the period of Life Extension. In many cases this requires detailed fatigue analysis and inspection programs to demonstrate that original fabrication flaws or fatigue cracks that may have existed during the welding of the riser joints or initiated over the original Design Life will not grow to a critical size resulting in failure.
Engineering Critical Assessment (ECA) is now routinely applied in the design and fabrication of new offshore riser systems to develop girth weld flaw acceptance criteria. The resulting flaw acceptance criteria ensure that fabrication flaws will not extend to a critical size over the Design Life and thus the riser still meet its calculated fatigue life. Although ECA procedures for new construction are well established and standard practices have been adopted throughout the industry, ECA procedures for Life Extension have not yet evolved to the same level of acceptance.
This paper will review specific issues associated with applying ECA to support Life Extension of offshore Riser Systems. The paper will provide the overall ECA philosophy and methodology for life extension to be adopted for the historical (hindcast or Phase 1) and future (forecast or Phase 2) analysis of the risers. Some thoughts will also be given to the approach implemented to take advantage of the actual weld fabrication data with the focus on the fatigue critical sections of the risers. Finally, the paper will address the requirements for riser in-situ inspection and how the results could be analyzed and applied to the life extension analysis in conjunction with the ECA analysis.
Experimental Study on the Flow Around a Rotating Cylinder
Authors: Rheem Chang-Kyu 
Published: December 2020

Abstract
The flow around a rotating cylinder has been investigated at the experimental water basins. The tangential velocity generated by the rotation of the cylinder decreases linearly with the logarithmic value of the distance from the cylinder surface, and has a constant distribution in the radial direction regardless of the rotation speed. The distance at which the tangential velocity becomes zero is about 4.35 times of the cylinder radius from the cylinder center. The energy transfer is greater near the cylinder than far from the cylinder and proportional to the proportionality coefficient A of the linear equation of velocity distribution. In a narrow water basin, the influence of the rotation is not absorbed completely to the water and a flow was formed in the water basin.
Hydrokinetic Energy Conversion by Flow-Induced Oscillation of Two Tandem-Cylinders of Different Stiffness
Authors: Yuan Wenyong , Sun Hai , Beltsos Nicholas , Bernitsas Michael M. 
Published: December 2020

Abstract
The VIVACE (Vortex-Induced Vibration for Aquatic Clean Energy) Converter harnesses hydrokinetic energy by enhancing flow-induced oscillations (FIOs) of elastically supported rigid cylinders in a river, tide, or ocean current. The harnessing power depends on the intensity of the oscillation, which is a consequence of the flow-structure interaction. The inflow condition for the downstream (2nd) cylinder is slowed down and perturbed by the upstream (1st) cylinder, due to the shielding effect. Therefore, the optimal structural parameters, i.e., stiffness and damping ratio, for the 2nd cylinder may be different from the 1st cylinder, in terms of energy harnessing.
To improve the performance of the VIVACE Converter, a series of experiments are conducted in a recirculating water channel, with various stiffness combinations of two cylinders in tandem. Three center-to-center spacings, six damping ratios, and seven combinations of spring stiffness are tested. The stiffness of the 1st cylinder, K1, is 600 N/m or 1,000 N/m, while the stiffness of the 2nd cylinder, K2, varies from 400 N/m to 1,200 N/m in increments of 200N/m. Results show that K2 does not affect the energy harnessing power in vortex-induced vibration (VIV) occurring at low speeds, but has great influence on the harnessing power at higher velocities in the transition region from VIV to galloping and in galloping. Decreasing K2 onsets and enhances galloping at lower flow velocity and harnesses up to 110% more energy than the case of K1 = K2. For K1 = 1,000 N/m, the harnessed power is the same for all the combinations of K1 and K2. The overall performance is best when K1 = K2. As spacing increases, the impact of K2 is diminished as explain by the dependence of power on the amplitude and frequency of cylinder oscillations.
Retracted: “Numerical Simulation and Experimental Research of Hydrophone Flow Noise” [ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering, Volume 6B: Ocean Engineering, Virtual, Online, August 3–7, 2020, Conference Sponsors: Ocean, Offshore and Arctic Engineering Division, ISBN: 978-0-7918-8438-6, Copyright © 2020 by ASME. Paper No. OMAE2020-19121, V06BT06A057; 7 pages; doi: 10.1115/OMAE2020-19121]
Authors: ASME  
Published: December 2020

Abstract
This paper was removed from publication at the author’s request. January 15, 2021.
Copyright © 2021 by ASME
World’s First Carbon Sequestration Project in Salt Caverns Built Offshore in Ultra Deep Water in Brazil
Authors: da Costa Pedro Vassalo Maia , da Costa Alvaro Maia , Meneghini Julio Romano , Nishimoto Kazuo , Assi Gustavo , Ebecken Nelson Francisco Favilla , Pinguelli Rosa Luiz , Miranda Antonio Carlos de Oliveira , Goulart Mariana Barbero Ribeiro , Bergsten Andre , Brandão Camila 
Published: December 2020

Abstract
In 2006, giant oilfields were discovered in Brazil in a water depth of ∼ 2200 m and under a caprock of 2000 m of continues salt rock overlaying the reservoirs, called pre-salt. Currently more than a half of the Brazilian oil and gas production comes from these reservoirs. However, some of these assets have big Oil & Gas ratio with a high level of CO2 contamination, which are currently being reinjected in the reservoirs. This procedure gradually increases the CO2 content associated with the oil extracted, reducing well productivity and leading to high costs of CO2 and CH4 separation by the membrane technology. The Research Center for Gas Innovation (RCGI) located at the State University of São Paulo in Brasil, sponsored by Shell Brazil, is developing a technology that uses the thick layer of salt rock overlying the pre-salt reservoirs to build caverns where the contaminated gas will be injected and decontaminated. After 2 years of extensive research, several studies have been carried out to analyze the main critical aspects of the technology in order to evaluate its feasibility, and now it has been decided to advance to the field proof stage. The salt dome studied can accommodate the construction of 15 caverns, thus providing the confinement of approximately 108 million tons of CO2. Before the system be construct in full scale, it was decided to initially build an experimental cavern with smaller size to obtain field parameters of the final design of the caverns. This paper describes this development denominated Offshore Salt Cavern Ultra-deep Water CCS System, that aims to perform the natural gas storage, a natural gravitational separation between CO2 / CH4 inside the caverns, and the confinement of CO2 (CCS). It presents important results related to structural integrity analysis of the giant and experimental caverns, well design using the same methodology applied in more than 200 projects of the pre-salt oil wells, instrumentation plan of the experimental cavern, storage capacities and other relevant data. If the economics proves feasible, this offshore gas storage station will be the first of its kind and possibly the biggest CCS Project in the world.
A Random Method for Calculation of Hoisting Drag
Authors: Qiu Hongyuan , Yang Jianming , Rideout Geoff , Butt Stephen 
Published: December 2020

Abstract
In reality, downhole conditions are highly unpredictable due to many uncertain and inconsistent factors, such as the uncertainty of the friction and contact between drillstring and bore-hole. As friction and contact are crucial components in torque and drag calculation, it is meaningful and practical to consider their uncertainty. This paper presents a random method for calculation of hoisting drag. Firstly, the finite element method (FEM) is used for hoisting drag calculation of a directional drilling well using Adanoy’s method in the deterministic case. Then two strategies are taken to model the random component in the downhole. The first strategy considers the randomness of the downhole friction. Instead of being a deterministic value, the friction coefficient is considered as Gaussian. The second strategy considers the randomness of contact between drillstring and wellbore. As a result, the drillstring is no longer continuously contacting with the wellbore in the curved section of well profile, which can help avoid overestimating torque and drag. Parametric studies on both strategies are conducted. Monte Carlo (MC) simulation is employed for statistical analysis. The probability density distributions and mean values of drag will be studied. The methodology can be extended into torque or drag calculation in lowering, ream in and ream out drilling conditions. Results from this paper indicate that surface hoisting drag is nearly Gaussian when the friction coefficient is Gaussian. The contact loss leads to considerable reduction in the surface hoisting drag when contact uncertainty is considered. The work of this paper will help estimate the range of surface drag and torque, which allows the well planner to develop a risk assessment for a challenging well trajectory.
Optimization of Both the Layout of an Array and the Buoy Dimension for Two Types of Arrays
Authors: Lyu Jianyang , Abdelkhalik Ossama , Zou Shangyan 
Published: December 2020

Abstract
This paper explores optimal configuration of both dimension and layout of Wave Energy Converter (WEC) arrays with full interaction and exact hydrodynamics. Arrays in this research contain devices that operate in heave mode and also devices that operate in pitch mode. The hydrodynamic interaction between buoys in the array is studied and higher q-factors is achieved using optimization. This study includes optimization results for arrays of only heave-mode buoys and hybrid arrays of 2 types of devices that has been mentioned above. Each of the heave-mode arrays contain 3, 5, and 7 buoys respectively while the hybrid arrays have arbitrarily selected configurations of the type of devices for comparison. This simulation uses impedance matching control which provides theoretical maximum level of power. The results indicates it is essential to optimize array layout simultaneously with the dimension of each buoy. Meanwhile, the mode of motion of the devices in an array is a significant factor in designing the array under complex ocean environment, and better performance of the array is achieved when the configuration is selected properly.
Numerical Investigation on Behaviors of Stiffened Large Suction Cap for Offshore Suction Cofferdam
Authors: Kim Jeongsoo , Jeong Yeon-Ju , Park Min-Su , Song Sunghoon 
Published: December 2020

Abstract
This study introduces a large offshore cofferdam installed by suction, unlike conventional ones such as a sheet-pile type, and proposes an effective suction cap for the cofferdam. In structural design view of the cofferdam, there are several critical issues due to its large size. This study conducted structural analyses of stiffened caps for large offshore suction cofferdam using fully nonlinear finite element models, and analyzed changes in behaviors of the cap due to stiffener arrangements to provide design insights. For finite element models, the diameter and the thickness of the suction cap (circular plate only) are 20m and 0.07m, respectively. Suction pressure on the cap was assumed to be 100kPa, all parts of the cofferdam except the cap are considered as boundary conditions. By investigating conventional suction anchors, several stiffener arrangement patterns on the cap of suction cofferdam were derived, and each arrangement was estimated by comparing stress and deformation of the cap. Also, reaction distributions on the edge of the cap were investigated to analyze effects of the stiffener arrangement on the interface behaviors between cap and cofferdam.
Development and Verification of Modeling Practice for CFD Calculations to Obtain Current Loads on FPSO
Authors: Koop Arjen , Yeon SeongMo , Yu Kai , Loubeyre Sebastien , Xu Wei , Huang Jerry , Vinayan Vimal , Agrawal Madhusuden , Kim Jang 
Published: December 2020

Abstract
Current loads are important input parameters for mooring studies. To accurately predict the motions of moored vessels these quantities should be determined with confidence in the values. Traditionally, these quantities have been determined using model tests in water basins or in wind tunnels. With recent advancements in CFD modeling, the offshore industry has started using CFD as an alternative tool to compute current loads on FPSO’s. In order to help adopt CFD as a widely accepted tool, there is a need to develop confidence in CFD predictions. Therefore, a practical CFD Modeling Practice is developed within the Reproducible Offshore CFD JIP. The Modeling Practice describes the geometry modeling, computational mesh, model set-up and post-processing for these types of CFD calculations. This Modeling Practice is verified and validated by five independent verifiers against model test data, such that reproducible and accurate results can be obtained by following the Modeling Practice.
This paper provides an overview of the developed Modeling Practice and the calculated CFD results from the verifiers. The CFD Modeling Practice is benchmarked against available model test results for a barge-type and a tanker-shaped FPSO. By following this Modeling Practice, the CFD predictions for CY and CMZ are within 10% from all verifiers and within 10% from the model test results. Larger differences may be obtained for CX, depending on local grid resolution and turbulence model used, but also due to larger experimental uncertainty for this quantity.