Segen Farid Estefen

Segen Farid Estefen
Federal University of Rio de Janeiro | UFRJ · Department of Ocean Engineering

PhD

About

217
Publications
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2,385
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Publications

Publications (217)
Article
Hull girder ultimate strength is an essential parameter for the ship's structural design. Numerous research studies have been done about hull girder bending. However, few experimental tests have been carried out due to the fabrication cost, the difficulty of monitoring loads, and mapping surfaces of models on large-and medium-scale. This paper cond...
Article
Sandwich pipes (SPs) with adequate strength performance and thermal insulation capacity have become an attractive choice for oil and gas transportation in deep water. The SP has a more complex structural configuration than the traditional single wall pipe. The fabrication process can induce eccentric behaviours of the pipe layers, influencing the e...
Article
Sandwich pipe with high-pressure resistance and the adequate insulation performance is a potential deepwater offshore oil and gas development solution. This paper establishes a two-dimensional finite element numerical model for sandwich pipe collapse prediction under external pressure using the finite element software ABAQUS. The developed numerica...
Article
Flexible pipes have been used for decades for conveying produced fluids from oil wells to floating production, for storing and offloading units, and for flowing injection fluids inside wells under the seabed. Over the years, with an increase in oil demand globally, the exploration of new and deeper oil reservoirs has become a reality. With greater...
Article
Full-text available
The latching control represents an attractive alternative to increase the power absorption of wave energy converters (WECs) by tuning the phase of oscillator velocity to the wave excitation phase. However, increasing the amplitude of motion of the floating body is not the only challenge to obtain a good performance of the WEC. It also depends on th...
Article
Full-text available
The paper presents the development of a downscaled hardware-in-the-loop (HiL) setup for a wave energy converter heaving point absorber. HiL simulation involves the buoy motion coupled to a gearbox system that converts the buoy’s vertical movement into rotational. The dynamic movement of the heaving buoy is simulated and converted into rotation. A p...
Article
Full-text available
A study of the migration of the grain boundary misorientation and its relationship with the residual stresses through time immediately after the completion of a thermomechanical simulation has been carried out. After physically simulating an intercritically overheated welding heat affected zone, the variation of the misorientation of grain contours...
Article
Full-text available
The modelling of nonlinear viscous effects for a wave energy converter (WEC) under control systems represents a difficult task. The control system aims to maximize the power capture of WECs. Consequently, large velocities of these devices observe. In addition, the linear potential theory is unable to show a realistic prediction of power production...
Article
The growing increase of offshore wind implementations has been made this modality subject to many resource assessment works. However, the variety of available wind datasets and the difficulty of the validation process over the ocean still leave uncertainty about the most relevant data for offshore wind resource assessment and how much they affect t...
Article
Full-text available
Coastal ocean observing and modeling systems (coastal observatories), connected with regional and global ocean systems, improve the quality of information and forecasts for effective management of safe and sustainable maritime activities. The public availability of systematic and long-term information of the ocean is an engine for the Blue Economy,...
Article
As one of the renewable and clean energy sources, wave energy has high density and all-day availability characteristics. However, the development of wave energy converters has been hampered, mainly because of the low efficiency induced high levelized energy costs. The present study introduces an improved bistable mechanism composed of three linear...
Article
Full-text available
In recent years, the wind turbine market has gained relevance due to technological advances that make this renewable energy type increasingly efficient and economically competitive. Numerous studies have focused on the rotor blades due to their design process and constant increase in dimensions. During their useful life, the blades are exposed to c...
Article
Full-text available
Lower efficiencies induce higher energy costs and pose a barrier to wave energy devices’ commercial applications. Therefore, the efficiency enhancement of wave energy converters has received much attention in recent decades. The reported research presents the double snap-through mechanism applied to a hemispheric point absorber type wave energy con...
Article
Sandwich pipe (SP) combining high-strength performance and thermal insulation has been considered an effective solution for oil and gas transportation in ultra-deepwater. Strain hardening cementitious composite (SHCC) is well known for its capacity to withstand both tensile load and external hydrostatic pressure. The sandwich pipe considered in the...
Article
Sandwich pipe (SP), composed of two concentrically steel tubes with a strain-hardening cementitious composite (SHCC) filling core, is a new concept designed for oil and gas transportation in deep waters. Bending is a primary loading condition for the SP during the installation process. There is currently a lack of research on SPs' bending capacity,...
Article
The objective of the paper is to perform a review of the environmental impacts of the installation, operation and maintenance (O&M), and decommissioning of offshore wind technologies. At first, a comprehensive review is presented on offshore wind technologies and techniques related to the installation, O&M, and decommissioning stages. Then a thorou...
Article
This paper focuses on the concept of a subsea satellite well system in deep water oil field, and a mixed-integer nonlinear programming model (MINLP) is proposed to help design the layout to minimize the payback period. The proposed model has two key aspects. First, the objective function, payback period, reflects the link between the total cost and...
Article
The subsea manifold as the hub oil and gas transportation equipment is a critical part for the layout optimization of subsea production system and reducing the number of pipelines. The traditional subsea manifold is fixed on seabed by its foundation, so traditional manifold system is hard to be discarded and recovered although it has many advantage...
Article
Due to the complexity of installations and connections of subsea production equipment and the massive structures involved in a challenging environment, the failure of subsea production equipment could induce enormous loss to the safety and reliability of structures in addition to the cost of the oilfield development. One of the challenges that the...
Article
Several latching control strategies have been proposed to improve the power performance of wave energy converters (WECs). However, the benefits and challenges vary for different WECs and PTO systems. This paper addresses the power performance of a specific direct mechanical-drive power take-off (DMDPTO) system considering the application of a non-p...
Chapter
Heavy oil production in deepwater is a major challenge to pipeline technology due to high viscosity and associated high pressure drop. In this chapter, we propose to apply active electrical heating in multilayered composite pipelines for heavy oil production in deepwater. A thermal-hydraulic analysis is carried out to evaluate the pressure drop red...
Chapter
In this chapter, a fluid-structural model for analyzing the dynamic behavior of riser vibration subjected to simultaneous internal gas–liquid two-phase flow and external marine current is proposed. Slug flow regime is considered as it causes most violent vibrations. An analytical model is adopted for the prediction of important flow characteristics...
Chapter
In this chapter, we first present a global heat balance analysis of typical pipelines for deepwater oil and gas production and show that active heating is necessary for long pipelines due to technical limitations of passive thermal insulation systems. Two methods of combined active heating and passive insulation are then considered. By the first me...
Chapter
In this chapter, a numerical and experimental study is performed to investigate the collapse behavior of sandwich pipes considering the reel-lay installation method. Experimental models are manufactured using two different geometries of stainless steel pipes and strain hardening cementitious composites (SHCC) with PVA fiber in annular layer. One se...
Chapter
Sandwich pipes (SP) with steel tubes and a lightweight flexible core are under consideration as a potential solution for ultra-deepwater submarine pipelines, combining high structural resistance with thermal insulation. Besides polymeric materials, strain hardening cementitious composites (SHCC) reinforced with polyvinyl alcohol (PVA) fibers, a mic...
Chapter
Dynamic behavior of axially functionally graded (FG) pipes conveying fluid is investigated numerically by using the generalized integral transform technique (GITT). The transverse vibration equation is integral transformed into a coupled system of second-order differential equations in the temporal variable. The Mathematica’s built-in function, NDS...
Chapter
Buckle propagation of local collapse appearing in the damaged pipes is one of the failure modes that are of particular interest for deepwater application. The local collapse can propagate along the pipeline for long distances in both directions when the external pressure magnitude is up to the propagation pressure. In this chapter, the buckle propa...
Chapter
Fundamentals of thermal analysis of pipelines are presented in this chapter. Formulations for heat conduction in single-layer and multilayer pipelines are presented. The steady-state distribution of the temperature of produced fluid along the pipeline is determined analytically.
Chapter
Sandwich pipes consisting of two concentric metal pipes with insulation material in annulus have been developed to meet challenging mechanical and thermal requirements of deep and ultra-deepwater oil and gas production. Passive thermal insulation is designed to meet flow assurance requirements under steady-state production conditions, but is unlike...
Chapter
Sandwich pipes (SP) can be an effective solution for the ultra-deepwater submarine pipeline, combining high structural resistance with thermal insulation capability. Besides polymer, steel fiber reinforced concrete (SFRC) can be another choice for the annular material, based on the characteristics of high fracture toughness and good adhesion with m...
Chapter
In this chapter, we review the generalized integral transform technique (GITT) approach adopted to analyze some typical structural dynamic problems. The Sect. 7.2 general solution methodology to solve the vibration problems is presented. Special topics and applications including the vibration of axially moving Euler beams, axially moving Timoshenko...
Article
This book focuses on advanced methods for the structural and thermal analysis of deepwater pipelines and risers. It discusses the limit strength of sandwich pipes, including finite-element analysis using Python scripts, collapse of sandwich pipes with cementitious/polymer composites, buckle propagation of sandwich pipes, dynamic behavior of subsea...
Article
Repair by welding is widely used in the shipbuilding industry during ship construction. The effect of the residual stress distribution induced by the welding process on the ship structure is important for the repair effectiveness. This article presents an experimental study of the residual stress distribution induced by repair welding in the plates...
Conference Paper
Recentemente em nossos trabalhos foram apresentados resultados experimentais sobre o efeito de redistribuição, em curto intervalo de tempo, das tensões residuais de soldagem no caso da solda de topo para chapas e tubos, bem como solda de reparo para chapas navais. Neste trabalho serão apresentados resultados sobre o comportamento das tensões residu...
Conference Paper
Full-text available
In recent years, the wind turbine market has gained relevance, due to technological advances that make this type of renewable energy increasingly efficient and economically competitive. Numerous studies have focused on the rotor blades, due to their design process and constant increase in dimensions. During their useful life, the blades are exposed...
Conference Paper
Full-text available
Offshore wind energy has shown a wide potential for sustainable electricity generation. High-resolution wind data, although scarce over the ocean, are necessary to carefully analyzes the available resources. The atmospheric modeling has become a key tool to overcome the data limitation. The paper aims to assess the resource potential and cost estim...
Conference Paper
Full-text available
Several offshore wind turbine manufacturers are designing wind turbines with rotor diameters larger than 200 m. An accurate prediction of the aerodynamic loads acting on these large-scale wind turbines is crucial for the reliable prediction of the fatigue life of these massive machines. These loads depend primarily on the atmospheric boundary layer...
Chapter
In this chapter, improved lumped parameter models are applied for transient thermal analysis of multilayered composite pipeline with active heating, which is essential for flow assurance design and operating strategies of deepwater subsea pipelines. Improved lumped models for transient heat conduction in multilayered composite pipelines are based o...
Chapter
Pipe–soil interaction has been intensively investigated both theoretically and experimentally due to its importance in the design of seabed pipelines. In recent years, the effects of single phase, steady internal flow on the dynamic response of seabed pipelines have received increasing attention. However, the effects of transient two-phase flow on...
Chapter
In this chapter, the dynamic behavior of pipes conveying gas–liquid two-phase flow is analytically and numerically investigated on the basis of the generalized integral transform technique (GITT). The use of the GITT approach in the analysis of the transverse vibration equation leads to a coupled system of second-order differential equations in dim...
Chapter
Sandwich pipes can overcome the shortcomings of the single-walled steel pipe and achieve the flow assurance in deepwater environments. This chapter reviews most of the research done in recent years on the buckling, collapse, and buckle propagation of SP, which emphasized on the development of theoretical, experimental, and numerical methods adopted...
Article
Over the last decade, a dramatic increase in the size of commercial wind turbines is noticeable. The optimal structural design and reliable fatigue-life prediction of these large-scale structures depend on the accurate modeling of the turbulent flow around the rotors. The present paper aims at extending the knowledge of the turbulent flow character...
Conference Paper
The electricity demand of offshore oil and gas platforms are traditionally supplied by gas turbines operating with natural gas extracted from the field or fossil fuels emitting CO2 and NOx. Offshore wind power is an interesting alternative to supply such a demand as it can be produced close to the oil and gas field and providing clean and renewable...
Article
Sandwich pipes (SPs) composed of two concentrically steel tubes with a strain hardening cementitious composite (SHCC) filling core is a new concept designed for oil and gas transportation in deep waters. In this concept, the SHCC core is the most critical component that should withstand the combined loading of high hydrostatic pressure and bending...
Article
The concept of sandwich pipes for subsea applications has been studied independently of an available connection to joint the pipe segments. Therefore, it is necessary to propose and study the design of a pipe segment connection to build a continuous sandwich pipeline. The reported research work suggests using threaded connections of integral type w...
Article
The interest in predicting the force required for a subsea blowout preventer (BOP) to cut and isolate the drilling pipe has been growing since the Macondo accident. In previous research, numerical simulation using the nonlinear finite element method combined with the blowout preventer (BOP) shear test has been a common approach. As various fracture...
Article
This paper focuses on the study of the influence of indentation parameters on the ultimate strength and behavior of the damaged panels for two types of stiffeners, through an experimental-numerical correlation and a paramet-ric study. Experiments were performed using stiffened panels in small-scale models, with stiffener type T and flat-bar, repres...
Book
Full-text available
This is a reprint of articles from the Special Issue published online in the open access journal Energies (ISSN 1996-1073) from 2018 to 2019 (available at: https://www.mdpi.com/journal/energies/special issues/marine).
Article
Full-text available
The welding numerical simulation involves thermal and mechanical analyses and metallurgical consideration. The thermal analysis determines the transient temperature distribution on the welded part, and its accuracy is relevant for the following analyses on structural integrity, in particular buckling and fatigue failure modes of steel-plated struct...
Article
The paper presents an assessment of the technical potential of the offshore wind resources of the Southeast and South regions along the Brazilian coastline using atmospheric reanalysis databases. At first, three atmospheric reanalysis databases, CFSv2, ERA5 and MERRA2, are validated using measured data provided by the PNBOIA program. Afterwards, to...
Article
A comprehensive study on the collapse pressure and post-buckling behaviour of a sandwich pipe (SP) with a core of strain-hardening cementitious composite (SHCC) was carried out in Part 1 of two companion papers. The results in the Part 1 paper show that an SP with an SHCC core has a different collapse mechanism from an SP with a polypropylene core....
Article
Combining both thermal insulation and structural strength in the core, sandwich pipes (SP) are a promising alternative for conventional single wall pipes in deep-water applications. The ultimate strength of SPs under external pressure has always been a major concern in the design process. An insightful understanding of the collapse pressure and pos...
Article
The increasing of deepwater oil field developments brings a growing need for thermal management to prevent hydrate and wax formations in the subsea production system, due to the low environment temperature and long-distance transportation. Pipeline insulation coating is a typical strategy for thermal management. In a subsea production system, press...
Article
Full-text available
Welding is widely used in the manufacture of steel products. Metallurgical processes during welding produce residual stresses in different zones of the welded parts. Welding residual stresses, particularly tensile stresses, can significantly impact the reliability and the integrity of the welded components. Our recent works report the effect of res...
Article
Full-text available
This study, firstly, provides an up-to-date global review of the potential, technologies, prototypes, installed capacities, and projects related to ocean renewable energy including wave, tidal, and thermal, and salinity gradient sources. Secondly, as a case study, we present a preliminary assessment of the wave, ocean current, and thermal gradient...
Article
Mechanical restoration of a point absorber (PA) wave energy converter (WEC) featured a nonlinear stiffness system built by conventional mechanical compression springs (NSMech). Numerical simulations conducted here considered irregular waves in a specific sea site. Results showed considerable improvement for a given suitable spring configuration (le...
Article
Subsea pipe route selection is very complex which involves several issues due to the complicated sea environment. A properly selected subsea pipe route could help reduce costs and meet engineering requirements. While simultaneously considering the related requirements, this task becomes a complicated optimization problem. This paper proposes a nonl...
Conference Paper
During subsea offshore drilling operations, the floating vessel is connected to the wellhead through a series of equipment assemblies. The riser is exposed to dynamic loads from currents, waves, and drilling platform motions. Therefore, a dynamic analysis of the riser system is required to obtain forces and moments in the wellhead. It is even more...
Conference Paper
Full-text available
Com o aumento da produção de petróleo em alto mar, o uso de risers flexíveis tem se elevado. Formando a conexão entre o poço e a plataforma, estes dutos estão sujeitos aos carregamentos causados pela união dos esforços mecânicos e ao ambiente corrosivo. Com diversos possíveis modos de falha, torna-se de grande importância o monitoramento da sua int...
Article
Oil-and-gas field development projects are capital-intensive, and optimizing profitability has always been a critical subject for the industry. This paper presents a mixed-integer linear programming (MILP) model to facilitate scenario comparison and selection at the design stage for green offshore oil-field development. The model solves an allocati...
Article
Thermal insulation is widely used in offshore oil production for flow assurance design. Research efforts have concentrated on the thermal and mechanical properties of the insulation material, but few publications have focused on the optimization of the insulation. For certain subsea production systems, several optional insulation materials are avai...
Conference Paper
As the tendency of the offshore oil industry is going deeper and further, the subsea pipeline is exposed under tougher condition combining lower temperature with higher hydrostatic pressure. The severe condition creates a challenge towards flow assurance, which often results in a high cost solution. Reducing the cost while providing a qualified ins...
Conference Paper
The increasing of deepwater oil field developments brings a growing need for thermal management to prevent hydrate and wax formations in the subsea production system, due to the low environment temperature and long distance transportation. Pipeline insulation coating is a typical strategy for thermal management. In a subsea production system, press...
Conference Paper
A subsea Blowout Preventer system plays an extremely important role in providing safe working conditions for drilling activities in deepwater oil exploration. However, estimating the performance of Shear Ram Blowout Preventeris still a challenge for the industry. This paper considers different scenarios that may influence the shear capability of a...
Conference Paper
A review of accidents involving collisions between ships and offshore platforms was carried out. There are reports and publications that present numbers, statistics and even details of the most important collisions between ships and offshore platforms, especially considering the North Sea region, but publications about accidents in Brazilian waters...
Conference Paper
During activities of ultra-deepwater exploration using drilling vessels an emergency disconnection between Lower Marine Riser Package (LMRP) and Blowout Preventer (BOP) stack could occur due to extreme environmental conditions. The disconnection is not instantaneous; it takes time due to the discharge of pressurized liquid from the system of hydrau...
Article
A properly arranged subsea production system reduces costs and contributes to production performance due to favorable hydraulic characteristics and flow assurance. Therefore, the layout design of subsea production systems is very important in offshore field development. The design of these systems mainly includes locating the subsea facilities, det...
Article
Apart from being induced by internal and external flow, vibration of free-spanning pipelines is also constrained by the soil that supports the span on both ends. A wake oscillator model is chosen to describe the vortex shedding acting on the pipeline, and the soil spring is adopted to describe the pipe–soil interaction at the span shoulders. A semi...