bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Novel Power Series Method for the Analysis of an Offshore Mooring Line
Authors: Kakanda Kabutakapua , Han Zhaolong , Yan Bao , Srinil Narakorn , Zhou Dai 
Published: October 2021

Abstract
The mechanics of offshore mooring lines are described by a set of nonlinear equations of motion which have typically been solved through a numerical finite element or finite difference method (FEM or FDM), and through the lumped mass method (LMM). The mooring line nonlinearities are associated with the distributed drag forces depending on the relative velocities of the environmental flow and the structure, as well as the axial dynamic strain-displacement relationship given by the geometric compatibility condition of the flexible mooring line. In this study, a semi analytical-numerical novel approach based on the power series method (PSM) is presented and applied to the analysis of offshore mooring lines for renewable energy and oil and gas applications. This PSM enables the construction of analytical solutions for ordinary and partial differential equations (ODEs and PDEs) by using series of polynomials whose coefficients are determined, depending on initial and boundary conditions. We introduce the mooring spatial response as a vector in the Lagrangian coordinate, whose components are infinite bivariate polynomials. For case studies, a two-dimensional mooring line with fixed-fixed ends and subject to nonlinear drag, buoyancy and gravity forces is considered. The introduced boundary and initial conditions enable the analysis of an equilibrium or steady-state of a catenary-like mooring line configuration with variable slenderness and flexibility. Polynomials’ coefficients computation is performed with the aid of a MATLAB package. Numerical results of mooring line configurations and resultant tensions are presented for deep-water applications, and compared with those obtained from a semi-analytical and finite element model. The PSM applied to the mooring line in the present study is efficient and more computationally robust than traditional numerical methods. The PSM can be directly applied to the dynamic analysis of mooring lines.
The Optimization Design of the Cross-Sectional Layout of an Umbilical Based on the Hybrid Genetic Algorithm
Authors: Yin Xu , Yang Zhixun , Shi Dongyan , Yan Jun , Wang Lifu , Lu Qingzhen , Tian Geng 
Published: October 2021

Abstract
The umbilical which consists of hydraulic tubes, electrical cables and optical cables is a key equipment in the subsea production system. Each components perform different physical properties, so different cross-sections will present different geometrical characteristic, carrying capacities, the cost and the ease of manufacture. Therefore, the cross-sectional layout design of the umbilical is a typical multi-objective optimization problem. A mathematical model of the cross-sectional layout considering geometric and mechanical properties is proposed, and the genetic algorithm is introduced to copy with the optimization model in this paper. A steepest descent operator is embedded into the basic genetic algorithm, while the appropriate fitness function and the selection operator are advanced. The optimization strategy of the cross-sectional layout based on the hybrid genetic algorithm is proposed with the fast convergence and the great probability for global optimization. Finally, the cross-section of an umbilical case is performed to obtain the optimal the cross-sectional layout. The geometric and mechanical performance of results are compared with the initial design, which verify the feasibility of the proposed algorithm.
Deepwater Span Management on a Mobile Seabed
Authors: Ang Sze Yu , Bernardo Arriane Chiara , Peek Ralf , Vedeld Knut , Caruso Mário , Wu Jie 
Published: October 2021

Abstract
This paper describes a multi-pronged continuous improvement effort to manage the spans of a deep-water pipeline, where even without wave action, the currents are strong enough to move sediments, leading to constantly changing spans. The effort includes: (1) using strakes rather than intermediate supports to suppress VIV, since the latter proved not to be a long-term solution, (2) using partial rather than full strake coverage of spans and developing tools to quantify the level of strake coverage that is required, (3) improving estimates of soil stiffness and damping, and tools to handle amplitude-dependent soil stiffness and damping, (4) performing pluck tests of the operating pipeline by pulling it laterally at midspan with the ROV until a weak link connecting the ROV to the pipe breaks, whereupon the resulting motion of the pipe is recorded with accelerometers, (5) developing tools that allow fatigue damage to be estimated and accumulated for every location along the pipeline (6) sponsoring a joint industry program by DNVGL to quantify the effect of seabed proximity and trench effects on VIV. This paper provides an overview of these activities, with emphasis on recent results and new assessment tools and methods developed and their validation covering items (2–4) above.
Integrated Optimization of Principal Dimensions Based on EEDI and Minimum Propulsion Power
Authors: Wang Yanxia , Sun Wenyu , Zhao Qiang 
Published: October 2021

Abstract
An integrated optimization model of EEDI and minimum propulsion power has been established in this paper. EEDI optimization needs to meet IMO requirements for minimum propulsion power. Installed power reduction is one of the most effective way to optimize EEDI, but it will make the installed power lower than IMO requirements. From the view of security, it is not allowed. In order to coordinate the contradiction between the reduction of EEDI and the minimum propulsion power of the ship, this paper is devoted to the development of an effective and efficient EEDI optimization method under the minimum propulsion power constraints of the ship. The evaluation method of the objective function EEDI is a digital pattern of hydrodynamics performance for tanker series developed by the China Ship Science Research Center. In order to illustrate the method, the VLCC is selected as the research object, and Non-dominated Sorting Genetic Algorithms II is selected to optimize the EEDI. The calculation results show that energy efficiency has been optimized about 4%, so the EEDI and minimum propulsion power integrated optimization model are reasonable and effective.
Review of Chemical EOR Projects in Venezuela: From Light to Extra-Heavy Oil Reservoirs
Authors: Rodriguez M. Fernancelys 
Published: October 2021

Abstract
Venezuela is widely recognized as an oil producer country of great potential thanks to its huge hydrocarbon resources located in Eastern Venezuela and Maracaibo basins, comprising the largest oil reserves in the world, with around 302 billion barrels according to recent OPEC and EIA estimates [1].
Despite those immense hydrocarbon resources, oil production in Venezuela is a challenge in mature and waterflooded reservoirs, as well as in thin highly viscous oil reservoirs where thermal IOR/EOR methods are not technically and/or economically feasible. This is the case of many oil fields in Lake Maracaibo and in La Faja Petrolifera Del Orinoco (La FPO), where the application of Chemical Enhanced Oil Recovery (CEOR) methods is being envisaged with a view to increasing oil recovery factors.
The objective of this article is to review most of the Venezuelan CEOR projects reported in the literature to identify the main insights/status of each reported project and its potentiality of application to increase oil recovery. A detailed description of each project and its main conclusions is given.
According to this literature review, CEOR project evaluations for Venezuelan reservoirs have been performed mostly at laboratory and numerical simulation scales, including several pilot test designs. Only 2 executed pilot tests have been reported (ASP flooding at VLA-6/9/21 Field in Lake Maracaibo and polymer flooding at Petrocedeño Field in La FPO). Despite the encouraging results in terms of oil recovery at laboratory scale, the greatest challenges related to the application of CEOR methods in Venezuelan reservoirs are linked to technical and economic aspects (e.g. high adsorption/retention of chemicals, mobility control, complex emulsions, separation of phases, water treatments, costs of investment, oil prices, etc.).
Nonlinear Roll Damping With Coupling Effect in Regular Beam-Wave
Authors: Asgari Peyman , Fernandes Antonio Carlos 
Published: October 2021

Abstract
Despite of numbers of method to estimate and predict the nonlinear roll damping, it is the mode least understood and the most difficult to determine so far. Reviewing the existing methods reveals that the coupling effects of other modes on roll motion are ignored by assuming just one degree of freedom (1DOF) roll in experiments. The new concept of Most Often Instantaneous Rotation Center - MOIRC proposed by Fernandes and Asgari has brough other parameters, which can help us to improve the roll damping analysis by including the coupling (roll-sway) that results in asymmetric roll responses. This paper, by describing experiments, aims to confirm this roll-sway effect on roll damping coefficient by taking a well posed 3DOF, which allows to follow the instantaneous rotation centers - IRCs. The regular beam-waves experiments were conducted for different frequencies and wave amplitudes. A 3DOF (sway, heave and roll) system identification is used to extract roll damping from the model test. It is shown that the locus of the IRCs follows a straight line and it has a statistical behavior whose probability density function of IRCs with a Cauchy probability density function. For the first time this characteristic is provided experimentally, well matching with the analytical Cauchy distribution.
Wettability Alteration During Low-Salinity Waterflooding in a Deep Tight Carbonate Reservoirs: A Quantitative and Visual Investigation Through Spontaneous Imbibition and Zeta Potentiometric Studies
Authors: Singh N. , Gopani P. H. , Sarma H. K. , Wu F. , Mattey P. S. , Negi D. S. , Srivastava V. 
Published: October 2021

Abstract
This study focusses on the investigation of wettability alteration behavior during low salinity waterflood (LSWF) process in a tight carbonate reservoir through Zeta potential studies in conjunction with spontaneous imbibition tests and estimation of the contact angle between the wetting fluid and the rock surface. This will help in understanding the role rock-oil-brine interactions play during an LSWF process. The classical streaming potential technique were used to determine Zeta potential. Measurements were carried out with diluted brines using different rock samples of in two states: oil-saturated and brine-saturated. The experimental results imply that the value of zeta potential becomes more negative with increasing percentage of dilution (25%, 10%, and 1%). This is attributed to electrical double-layer expansion which is caused, primarily, by the reduced ionic strength. We concluded that rock saturated with oil may give an insight on oil rock interactions while the rock saturated with brine may give insight on rock-brine interactions. The dilution of water helps increase the electrostatic repulsive forces between the two interfaces, which in turns, leads to the incremental recovery during LSWF process. This observation was also confirmed by coreflooding and wettability experiments through spontaneous imbibition tests and contact angle measurements conducted using the same oil-brine-rock systems. This is an investigative study of oil-brine-rock interaction behavior during a LSWF process that is difficult to accomplish through and during a conventional coreflooding displacement test. In addition, this study also couples the relationship between the wettability alteration and oil-brine-rock interactions during an LSWF process.
Research on Calculation Method of Density and Rheology of High-Temperature High-Pressure Drilling Fluid
Authors: Wang Lei , Yang Jin , Li Zhengkang , He Xinyue , Li Lei , Zhou Xu 
Published: October 2021

Abstract
With the strengthening of exploration and development of deep strata and offshore oil and gas resources, more and more deep wells and deep-water wells have put forward higher requirements for drilling fluid performance. The high-temperature high-pressure of deep well and the low temperature environment of deep well have important influence on the rheology and density of drilling fluid. A new method for calculating the rheology and density of high -temperature high-pressure (HTHP) drilling fluid is proposed and studied in this paper. In this paper, the HTHP rheological data are used to predict the shear stress under different shear rates, and then the wellbore rheological parameters are predicted and analyzed. For the calculation of drilling fluid density, the classical component method static density calculation model established by Hoberock model based on drilling fluid components is analyzed and improved in this paper. The obtained model predicts that the maximum absolute error of drilling fluid density under different temperature and pressure is 0.02 g/cm3, and the absolute error is controlled within 2 %.
Numerical Assessment of Turbulence Effects on Water Entry of a Hemisphere
Authors: Wang Shan , Guedes Soares C. 
Published: October 2021

Abstract
Water entry of a rigid hemisphere is simulated using the unsteady incompressible Reynolds-Average Navier-Stokes (RANS) equations and volume of fluid (VOF) method, which are implemented in the open-source library OpenFoam. The solver InterDyMFoam is applied and the algorithm PIMPLE which is a combination of PISO (Pressure Implicit with Splitting of Operators) and SIMPLE (Semi-Implicit Method for pressure-Linked Equations) algorithms are used in the simulations. A second-order backward difference scheme is applied for the temporal discretization. A convergence and uncertainty study is performed considering different resolutions and constant Courant number (CFL) using the procedures recommended by ITTC. The comparisons of slamming loads and motions between the CFD simulations are presented using both laminar and turbulence fluid models for the hemisphere entering the water at various speeds. Turbulence is modelled with a Reynolds averaged stress (RAS) k-ω two-equation model. The turbulence effects on the slamming loads will be assessed for the case with different entry velocities.
Evaluation of the Negative Stiffness Mechanism on the Performance of a Hinged Wave Energy Converter
Authors: Kamarlouei Mojtaba , Hallak Thiago S. , Gaspar Jose F. , Guedes Soares C. 
Published: October 2021

Abstract
This paper presents the numerical and experimental study of a new spring mechanism adapted to a cone-shaped point absorber wave energy converter (WEC). The WEC is intended to be hinged to a floating wind platform with a long arm to create a combined wind and wave harvesting concept. The main objective of the spring mechanism is to improve the platform restoring moments against the wind thrust forces, generated by the wind turbine while contributing to wave energy harvesting. However, the study is presented for the case where the WEC dynamics is investigated outside the platform and attached to a fixed frame, to validate the mathematical model of the WEC concept. Moreover, the impact on the power harvesting performance is investigated with and without negative springs in this scenario.
Micro-Siting of Floating Turbines Through Multiple-Criteria Decision-Making
Authors: Diaz Hugo , Guedes Soares C. 
Published: October 2021

Abstract
Multi-Criteria Decision Methods (MCDM) as a complement to current practices for identifying an initial compromise solution to the problem of wind turbine micro-siting are proposed. MCDM deals with multiple objectives in decision-making. The main goal of these methods is to choose among several alternatives using decision criteria previously defined. The use of MCDM guarantees the identification of the alternative that better performs than all the others according to the selected criteria. After a literature review on available methods for micro-siting of offshore wind turbines in a specific location, and an introduction to the MCDM, the usefulness and potential of MCDM in siting floating wind turbines is highlighted. The MCDM methods can add new parameters to the floating wind farms’ layout process. The results of this study support the potential role of these methods as crucial tools to technology developers and decision-makers.
Ultimate Strength Behavior of Cracked Ship Panels: a Review
Authors: Attia Ashraf , El-Kilani Heba S. , Saad-Eldeen S. 
Published: October 2021

Abstract
Cracks of various sizes and orientations may arise at many locations under conditions of pitting corrosion, local stress concentration, fatigue and impact loads. It is essential to evaluate the effect of cracks on the ultimate strength and collapse behaviors of various ship structural members, so as to avoid complete structural failure. The assessment of this effect would serve the life-cycle management, maintenance and repair strategies aiming to ensure structural longevity of ships and offshore steel structures. A review of the advances carried out during the last few years, shows that the effect of locked and propagated cracks on the ultimate strength behavior is complex since it cannot be isolated from the effect of initial imperfections and corrosion. Published experimental attempts were a good base, but most literature is based on finite element modeling that proved to be a useful tool to generate different possible damage scenarios. Recent empirical formulae had been proposed to estimate the reduction in ultimate strength due to cracks and other factors; some of these formulae may prove to have a practical use to attain a consequence based crack assessment criteria.
Direct CFD Simulation and Experimental Study on Coupled Motion Characteristics of Ship and Tank Sloshing in Waves
Authors: Huang Weigang , He Tao , Yu Jiawei , Wang Qing , Wang Xianzhou 
Published: October 2021

Abstract
It is of great significance to study the tank sloshing, especially the coupling motion between tank sloshing and ship in waves with strong non-linearity and randomness. In this study, the response of the ship with/without tank in regular wave is studied by EFD method and CFD method. All the simulations are carried out by in-house CFD code HUST-Ship (hydrodynamic unsteady simulation technology of ship) to solve RANS equations coupled with six degrees of freedom solid body motion equations. RANS equations are solved by finite difference method and PISO algorithm. A two-equation Shear Stress Transport (SST) k-w turbulence model is used. The simulation results are in good agreement with the experimental results, which also indicates that the result of the tank sloshing simulated by in-house CFD code is reliable. The influence of sloshing on ship motions is estimated by comparing the experimental results between the ship with/without tank in different wave conditions. The coupling motion characteristics between the liquid in the tank and the ship is further studied by the CFD method. The study shows that the influence of tank sloshing on ship motion is different under the action of different regular waves.
Probabilistic Models for Kick Tolerance
Authors: Kristoffersen Martine , Gomes Dalila , Fjelde Kjell Kåre 
Published: October 2021

Abstract
Kick tolerance is an evaluation of how large kick sizes i.e. kick volumes an open hole section can withstand without threatening the formation integrity at the shoe. If a certain kick size cannot be handled safely, the planned open hole section must be shortened, and the casing design must be altered.
Three models for calculating the kick tolerances in a well will be compared for a long and short open hole section for various lengths of bottom hole assembly (BHA). The kick tolerance will be performed probabilistically by use of Monte Carlo simulations where important input parameters are considered as distributions. The paper will focus on where the models differ in their results and discuss various opportunities and challenges with using a probabilistic approach.
The models will be integrated in a Monte Carlo simulation framework where the major input uncertainties will be pore pressure, fracture pressure and initial gas distribution in the well. The output will be a distribution of the casing pressure load that has to be compared to the fracture pressure distribution which results in a certain probability for fracturing for a given kick size. Only gas kick in water-based mud will be considered.
First a transient model based on the single bubble concept was considered and integrated in the Monte Carlo simulation framework. This was first compared against an analytical model which calculates the maximum casing shoe pressure at static shut in conditions. The analytical model considers uncertainty in the initial gas distribution. A transient flow model based on the drift flux model was also considered. Both short and long open hole length were considered. BHA length and kick size were varied.
The results show that the transient flow model provides the least conservative results but also the analytical model reduces the probability for fracturing compared to the single bubble model. In most cases, the maximum casing shoe pressure is achieved when kick is located at the BHA.
This paper extends the application of methods for reliability-based casing design to also include probabilistic kick tolerances. This is a contribution related to how the well design process can become more risk based. Some challenges related to specification of tolerance requirements, required number of Monte Carlo simulations and computing time will be discussed. It also provides an overview of the differences between the models and which parameters that are most important for the results.
Deepwater Steel Catenary Riser System Design for Lingshui 17-2 Project
Authors: He Ning , Yang Hu , Xu Fanli , Cheng Yongming 
Published: October 2021

Abstract
A riser is a key component for transporting produced oil and gas from the subsea wells to the surface production vessel. Through nearly 30 years of design and implementation, Steel Catenary Risers (SCRs) have been found to have the advantages of relatively low cost and good adaptability to floating platform’s motion. This paper investigates deepwater SCR system design for the Lingshui 17-2 (termed LS17-2) project.
This paper first introduces a SCR system for the LS17-2 project. The field for this project is located in the northern South China Sea, with water depth of 1220m to 1560m. LS17-2 consists of a subsea production system, a deep-draft semi-submersible (SEMI), and an export riser/pipeline. The platform was designed to have a large storage capacity with a variable draft during its operation.
Based on deepwater SCR engineering experience, the key SCR design challenges are summarized from the engineering executive perspective. The challenges to the SCR system design for the LS17-2 project include harsh environment condition in South China Sea and the impact on fatigue design for the requirement of 30-years’ service life. They call for design optimization and innovative ideas. The engineering design and analysis are discussed together solutions.
To demonstrate the deepwater SCR system design for LS17-2 project, examples are provided to illustrate the challenges and solutions. The experience learned from this paper should have significant relevance to future SCR design.