bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Lost Circulation Material Sealing Effectiveness in Water-Based and Oil-Based Drilling Fluids and Under Conditions of Mechanical Shear and High Differential Pressures
Authors: Klungtvedt Karl Ronny , Saasen Arild
Published: October 2022

A study was conducted to assess the performance of granular and fibrous lost circulation materials as preventative treatments and in remedial treatment of lost circulation in water-based and oil-based drilling fluids. For the preventative treatments, a factor which introduced increased mechanical wear on the particles were added to the hot-rolling process, to identify signs of deterioration of performance of certain materials.

The study of remedial treatments of lost circulation were conducted on slotted discs with apertures of 750 μm and up to 5 mm, and with differential pressured of up to 34.5 MPa (5000psi).

To compare the sealing pressures of the different tests, a simple statistical analysis was introduced to differentiate between the peak holding pressures and the sustainable holding pressures of the various material and fluids combinations.

The material degradation studies showed that CaCO3 based lost circulation materials rapidly experienced significant particle degradation after exposure to fluid shear and mechanical degradation and that this considerably reduced the sealing performance of the materials. Also, synthetic graphite-based products showed clear signs in particle size degradation and significant reduction in sealing performance. Cellulose-based products showed superior resistance towards mechanical wear and only small changes in sealing performance.

When comparing water-based and oil-based fluids, it was clear that granular lost circulation materials showed considerably lower sealing efficiency in oil-based drilling fluid compared to water-based drilling fluids. In contrast, cellulose-based materials showed similar sealing performance in oil-based fluids and water-based fluids.
Technical and Environmental Evaluation of a Hydrate Cold Flow Technique to Produce an Oil Reservoir Using a Long Tie-Back and Comparison Against Traditional Development Concepts
Authors: Eyni Leila , Fattahi Mostafa , Schümann Heiner , Lund Fredrik , Stanko Milan , Strømmegjerde Lars
Published: October 2022

In Norway, the majority of offshore oil and gas fields will be developed through tie-back solutions. Here, the produced reservoir streams are transported over long distances on irregular terrain and cold ambient temperatures to processing facilities. This might result in the formation of hydrate particles that can lead to increased pressure drop and gradual or sudden plugging of the pipe. Measures to address them tend to be expensive or have a high environmental footprint. An alternative measure less costly and more environmentally friendly is the cold flow technology. Here, hydrates are formed under controlled conditions, resulting in a stable particle slurry that does not agglomerate and plugs the pipeline downstream.

This study presents a technical and environmental evaluation of cold flow as a flow assurance technique to produce an oil reservoir using a long tie-back. The case study is a synthetic field located on the Norwegian Continental Shelf. Results show that cold flow can successfully be used to produce the reservoir with lower emissions. The advantages and limitations of the concept were identified and discussed, and a comparison is made against alternatives, considering energy consumption, emissions during operation, and carbon footprint.
Study on Large Particle Slurry Transport in Jumper for Subsea Mining
Authors: Masanobu Sotaro , Yamamoto Marcio , Takano Satoru , Murai Yuichi
Published: October 2022

For design and operation of subsea mining system, it is important to predict pressure loss due to the hydraulic transport of solid particles in the flexible jumper which connects the mining tool to the vertical lifting pipe via subsea slurry pump. The configurations of jumper would change according to the motions of the mining tool and the slurry pump, which may be easier to cause the pipe blockage than the vertical pipe.

In the present paper, we investigated the effects of jumper configuration on the pressure loss. We assumed the 100 m long flexible jumper of which outer and inner diameters are 0.254 m and 0.200 m, respectively. PMS ore, of which density and diameter are 3,440 kg/m3 and 0.03 m respectively, were assumed as the solid particles. We varied the slurry transport conditions such as slurry concentration and slurry velocity under the condition of a constant production rate of 5,000 t/day.

The effects of jumper configuration on internal slurry flow were studied from the viewpoint of pressure loss and specific energy consumption. The allowable slurry velocity in jumper system was also investigated considering pipe inclination by referring to the past literature. Finally, the most desirable operational slurry flow condition was discussed for the jumper system studied.
Improved Climate Change Adaptation in Port of Brisbane Using a Digital Twin Cloud-Based Modelling Approach
Authors: Karatvuo Helena , Linde Michael , Dolatshah Azam , Mortensen Simon
Published: October 2022

Due to their low-lying coastal location, ports are vulnerable to climate change induced increases to flooding, waves, extreme winds, and the associated costly damages to port infrastructure and operational disruptions. For these reasons, there is an increasing need for ports to undertake regular risk assessments of the vulnerability of their infrastructure and operations due to the impacts of climate change.

A digital twin, cloud-based climate change modelling solution has been developed to enable in-house risk assessments of climate change vulnerability to be undertaken for any port. Once set-up, the system supports the continued sustainable operation of ports and enhancing stakeholder confidence in corporate sustainability strategies by allowing in-house re-evaluation of the ports climate risk as new predictions are released.

The basis of the digital twin model of the port are numerical wave and hydrodynamic models, configured with the actual port geography and bathymetry enabling highly detailed simulations of the ports physical environment. The numerical model simulations are supplemented with observations of wind, rainfall, and sea level to identify trends and extreme event probabilities under the historic climate conditions. Scenarios describing the predicted impacts of climate change can be superimposed on the historical climate via a web-based interface where the user (port) selects a planning horizon (e.g., 2050), storm event frequency (e.g., 100-year storm), and climate change predictions (e.g. RCP8.5). The resulting climate change simulations shows great potential to enable port-specific predictions of future impacts of extreme occurrences of wind, waves, water levels, and currents. The ports asset portfolio is incorporated in the risk assessment through dynamic GIS layouts and damage curves identifying the damage cause and cost for each vulnerable port asset.

As new climate science becomes available, this cloud-based digital twin model enables ports to rapidly complete updated risk assessments and respond to stakeholder queries and concerns.

The capability of the tool was validated by comparing the model results against a large conventional study of the region, and a historical flood event of 2011. Both validation exercises displayed a reasonable agreement increasing confidence in the model’s capacity as a predictive tool. Additionally, six climate change scenarios were modelled for one of Australia’s fastest growing container ports, Port of Brisbane and the results were successfully incorporated in the ports overall sustainability strategy.
Fatigue Capacity of Used Mooring Chain - Results From Full Scale Fatigue Testing at Different Mean Loads
Authors: Gabrielsen Øystein , Reinholdtsen Svein-Arne , Skallerud Bjørn , Haagensen Per J. , Andersen Marius , Kane Pascal-Alexandre
Published: October 2022

Fatigue capacity of mooring chains is one of the important parameters in design of mooring systems for floating offshore structures. Fatigue life is often a limiting factor. With life extension of existing offshore installations, the fatigue capacity and effects of corrosion become even more important, as there will be large costs for mooring line replacements if safe life extension can not be granted, and the effect of fatigue failure can be fatal. Estimation of the fatigue capacity of mooring chains is thus of high importance both for safe and cost-effective design of new mooring systems, and for the safe life extension of older mooring systems.

The standards used for design of mooring systems outline a somewhat simplified approach for fatigue analysis, where load cycle range is the only parameter included in the analysis. The fatigue capacity curves used are based on full scale fatigue tests of new chains, where effects of heavily corroded surfaces are not considered. Further it is indirectly assumed that mean load does not have any effect on fatigue capacity. Work presented the last years has indicated a strong effect of both mean load and surface condition, where also formulas for fatigue capacity including these parameters have been developed and presented. The conclusions are based on a large set of full-scale fatigue tests of both new chains and used chains, where the used chains are tested at different mean loads and different levels of corrosion.

Equinor has run a large number of used chain fatigue tests. For these tests, each set of tests is typically made from one chain length, with similar condition on all links, and usually run at one mean load only. There are test sets with some variation in either mean load or surface condition, which have added valuable data for the understanding and verification of the effect of these parameters. The effects are well documented, but due to small variation within each set there are uncertainties regarding the quantification of the effects. The latest full-scale fatigue test results, from a chain with significant corrosion pits, include a systematic approach to quantify the effect of mean load. For the chain tested, five tests have been run at low mean load, and five tests at high mean load. This paper presents the results from these fatigue tests. The results are discussed and compared with other fatigue test results on both new and used chain, and with the formulas for fatigue capacity accounting for mean load and surface corrosion.
IMO Level 3: Parametric Roll Stability Failure Simulation Using 3D Numerical Wave Tank
Authors: Ganesan T. Shivaji , Negi Amresh , Sen Debabrata
Published: October 2022

In late 2020, International Maritime Organization (IMO) released interim guidelines on the second generation intact stability criteria. In this paper direct stability assessment in design situations using deterministic approach for parametric rolling failure mode is presented. A 3D nonlinear direct time domain method based on mixed-Eulerian-Lagrangian (MEL) scheme as opposed to impulse response function (IRF) method is used to simulate parametric rolling in both regular and irregular waves. Computed numerical results of roll amplitude in regular head waves is validated with other available literature results. This study further examines the influence of incident wave height and roll damping coefficient on computed heave, roll, and pitch motions in regular head wave conditions. Mean 3-hour maximum roll amplitude is obtained for design situations as recommended by the IMO guidelines.
Environmental Extreme Conditions for a Wave Energy Converter: An Integrated Wave-Structure Approach
Authors: Saeidtehrani Saghy , Lavidas George , Metrikine Andrei
Published: October 2022

The process of finding values of extreme waves and their impacts on wave energy converter (WEC) responses, depends on both wave resources and WEC dynamic characteristics. A wide range of waves can influence the reliability of operation and survivability of a WEC. In this paper, a methodology is described to find specific values of wave heights and periods that can be critical for a flap-type WEC, through the use of an integrated wave-structure approach.

The goodness of the fit is studied and the corresponding return periods for ranges that a selected WEC is mostly operating are evaluated. Further discussions for engineering applications and making a clear understanding of the extreme and operational conditions of the WEC are also provided. The critical wave characteristics are defined based on power production and the significant change in the nonlinear dynamic behavior of the device in various ranges.

The WEC behavior is represented by an experimentally validated numerical tool considering the nonlinear behaviour of a flap as single and in an array. The study aims to provide insights in the expected behavior and loading on the WEC, affecting its reliability, considering potential catastrophic wave return values that correspond to their power production phase. The finding can be used for determining both efficient operations and limiting environmental conditions or weather windows.
Pressure Build-Up in Closed Wells During Kick Migration and Fluid Compressibility Effects
Authors: Agonafir Mesfin Belayneh , Petersen Johnny , Fjelde Kjell Kåre
Published: October 2022

If a kick is migrating in a closed well, this will lead to pressures building up in the well. It has earlier been shown that for Non-Newtonian fluids, suspension effects will make it impossible to deduce a unique gas velocity from the pressure build-up behavior.

In this work, it will be shown that also for Newtonian fluids, the pressure build-up will depend on both kick size and well volumes. Both very small kicks sizes typically seen in MPD operations and larger kick sizes handled in conventional well control operations will be considered. It will be demonstrated that both the shape of the pressure build-up and the final pressure levels achieved will vary significantly. It is especially when considering very small kick sizes that one starts to see large changes in the profile of the pressure build-up. The main reason for the differences is related to the fact that the liquid phase is compressible and this will again have consequences for how much a gas kick can expand and what pressures it can bring to surface.

An analytical model will be developed that shows directly which parameters have impact on the pressure build-up behavior. Simple closure laws for gas density, fluid density and gas slip will be chosen. The model will be verified against two transient models which are based on the Drift-Flux formulation. It is demonstrated that the pressure build-up and final pressure level will depend on initial kick volume, initial fluid volume, liquid compressibility and fluid density. The effect of numerical diffusion when comparing the two transient models will also briefly be discussed.

The purpose of the paper is to increase fundamental knowledge about two phase flow dynamics and show that an analytical model for the situation considered here can give results that are comparable with the results achieved with more complex transient flow models.
An Alternative Measurement Method to Identify the Minimum Bending Radius of Locked Deformed Bend Restrictor Elements Under Load
Authors: Jordal Lars , Vermeer Erwin , Limi Morten , Karlsen Kjetil André
Published: October 2022

Bend restrictors (BR) are used during installation and operation of subsea power cables’ and umbilicals’ to limit the bending radius. This publication presents an alternative measurement method to qualify bend restrictors. One key parameter to qualify bend restrictors is the minimum bending radius (MBR). It is required to measure the MBR of the bend restrictor elements in lock-up position and deformed locked position under load. Existing guidelines, standards and test methods do not describe exactly how and by which means the MBR should be measured. As a result different measurement methods, models and assumptions are used in the industry. To the authors knowledge, existing measurement methods have a variety of limitations, for instance complex time consuming measurement set-up, limited accuracy and sensitive to errors. The alternative measurement method to identify the MBR, described in this publication, is based on a total station measurement technique. The total station consists of an electronic theodolite integrated with an electronic distance measurement unit, which measures the position of specified points in a 3d coordinate system. The alternative measurement method is easy to apply, less time consuming, more robust and can measure the MBR for all positions along the BR elements wirelessly.
Numerical Analysis on Model- and Full-Scale Unsteady Propeller Force for Underwater Vehicle
Authors: Takahashi Kenshiro , Arai Jun , Mori Takayuki
Published: October 2022

Submarines and other underwater vehicles must meet extensive specifications regarding their acoustic signatures to perform covert missions. However, marine propellers produce unsteady forces, resulting in undesirable noise. In this context, the unsteady propeller force of an underwater vehicle was analyzed at the model scale and full scale, based on computational fluid dynamics. The DARPA SUBOFF submarine and INSEAN E1619 propeller were adopted as benchmark models. The propeller rotational speeds under self-propelled conditions were determined using the body-force propeller method. The dominant harmonics of the unsteady propeller forces were analyzed using the Fourier series. The effects of pre-swirl flow generated by the helmed stern planes were investigated. Reynolds scaling was examined to predict the amplitudes of the propeller forces at full scale, based on the model-scale values.
American and European Hydrostatic Tubular Beam-Column Equation Comparisons
Authors: Ku Albert , Richmond Mark
Published: October 2022

For structural design engineers, there is an apparent gap on how the hydrostatic pressure is treated between the American and European systems. In API RP-2A, the beam-column equations treat the axial and bending capacities the same as there is no hydrostatic pressure. This is physically not correct, as member utilization is a combination among hydrostatic, axial, and bending actions. In contrast, the ISO and NORSOK beam-column equations include reductions of axial and moment capacities due to hydrostatic effect. In this paper, actual test data are compared with the API and ISO capacity equations. A third set of capacity equations provided by Chen et al. is also considered. Unity check (UC) results show that, although API equations lack the proper hydrostatic reduction in axial/bending capacities, it is compensated by the separate checks of hoop buckling and ultimate strength. For engineering applications similar member designs will be obtained by either the European or the American systems.
Research on the Influence of Waterjet Propulsion on the Attitude of Planing Ship
Authors: Yang Jun , Liu Liwei , Feng Dakui , He Tao , Yao Chaobang
Published: October 2022

Waterjet propulsion system is widely used in high-speed ships. It has the characteristics of low noise and high propulsion efficiency. In this study, the influence of waterjet propulsion system on the attitude of a planing ship is investigated by an inhouse CFD code. A series of numerical simulations are carried out for a waterjet-propelled ship which is composed of a waterjet propulsion system and a planing ship (DTMB 62 series model 4667-1). The bare hull in towing condition, waterjet hull in towing condition and waterjet hull in self-propelled condition are simulated at different volume Froude number. The ship attitude as well as the ship resistance is obtained. The numerical results of resistance, trim and sinkage of the bare hull agree with the experimental data. Furthermore, the impact of the waterjet system on the attitude of the ship is analyzed. The impact is divided into two parts: the impact of the shape changes on the hull and the impact of waterjet system operation. The impact of the shape changes on the hull makes the trim and sinkage increase under lower speed, while it makes them decrease under higher speed. The impact of waterjet propulsion operation makes the trim and sinkage tend to increase within the scope of the study.
Large-Eddy Simulation of Vortex Flow Field of the Cylinder With Variable Cross Section
Authors: He Tao , Liu Liwei , Yao Chaobang , Feng Dakui , Wang Xianzhou
Published: October 2022

In recent years, some scholars have proposed a pontoon tension leg platform, whose tension leg is in the form of variable cross section, but there is little research on vortex flow field of variable cross-section structure at high Reynolds number. Therefore, it is of great significance to study the vortex flow field of structures with variable cross section. In this study, the vortex flow field of the cylinder with variable cross section are studied in detail by large-eddy simulations. Structured grid is used for computation, and SIMPLEC algorithm is used to solve the pressure and velocity. Large-eddy simulation of flow past circular cylinder is carried out, and the simulation results accord well with the published experimental results, which shows that the numerical method is accurate enough. Large-eddy simulations are performed for flow past the wavy cylinders at Reynolds number of 61000. The lift and drag characteristics, pressure field structure and vortex field of the cylinder with variable cross section are analyzed. The results show that the mean drag coefficients and r.m.s (root-mean-square) of the lift coefficients of the wavy cylinders are less than those of a corresponding circular cylinder. The wavy cylinder changes the pressure field and vortex field relative to the circular cylinder.
A Computational Framework for Integrated Analysis and Hybrid Testing of Mooring Line Foundations
Authors: Abbiati Giuseppe , Zhang Zili , Franza Andrea , Andersen Lars Vabbersgaard , Stutz Hans Henning
Published: October 2022

Positional restraint of floating structures is achieved using mooring systems anchored to the seafloor. Design and risk assessment of these systems is challenging due to variability in wave, wind loading, ground conditions leading to uncertainty in the load-displacement behaviour of mooring line foundations for design. Accordingly, new simulation tools shall be able to support risk-informed integrated analysis of the floating structure as a system of interacting components subjected to realistic dynamic excitation. Also, all components of the floating structure simulation model shall be supported by experimental validation. In response to this need, this paper presents a computational framework for simulating the dynamic response of floating structures up to two second-order hydrodynamic loading. The framework utilizes the finite-element method and supports both integrated analysis and hybrid testing with focus on mooring line foundations. Computational efficiency is the driving criterion for tailoring the fidelity of the element library. Results of an ideal case study are used to test computational efficiency.
Analysis of Fluid Induced Transverse Forces on Multi-Strand Twisted Ropes
Authors: Schacht Stephan , Kosleck Sascha
Published: October 2022

Twisted multi-strand steel cables and ropes made of natural or synthetic fibres are the technical base for the manufacture of extended mechanically flexible structures. Examples can be found in a wide range of applications and subsystems throughout the maritime sector, e.g. experimental marine research, aquaculture, fishery and more. Here, one of the main concerns is the generated drag, a considerable quantity for flown through flexible structures. Furthermore, cables and ropes experience significant lift acting in the plain spanned by the cord vector, perpendicular to flow. In addition to that a transverse force occurs acting perpendicular to the plain spanned by the cord and inflow vector. This transversal force can generate significant deflections causing problems for example during towing processes. However, although of considerable impact this effect is often neglected with the underlying mechanisms not well understood.

This work presents an approach to derive these transverse forces examining the pressure distribution as well as the three-dimensional circulation around a multi-stranded rope. Following from that, two working theses are formulated:

1. The transverse force acting on multi-stranded ropes is a result of the circulation induced on the fluid by the geometry and its orientation to the incident flow.

2. The transverse force acting on multi-stranded ropes is comparable to the flow-induced hydrodynamic lift acting on an aerofoil.

With the use of experimentally determined pressure distributions across the surface of three-strand twisted rope segments at different angles of attack, cross-section-dependent circulation is demonstrated. The experimental data is compared with numerical calculations showing the limitations of a Reynolds-based approaches.
Study on Protective Structure Penetrated by the Shaped-Charge Jet for Ship Hull
Authors: Song Jingjing , Yue Jingxia , Li Xiaobin , Tan Runze
Published: October 2022

Based on the algorithm of Coupled Eulerian Lagrangian (CEL), the processes of the generation of shaped charge jet (SCJ) and the penetration to the inner and outer ship side plates were simulated by the finite element analysis (FEA). Meanwhile, the residual velocity of SCJ after penetrating the side plate could be obtained. In order to compare with the FEA results, the damage caused by the SCJ to the inner and outer plates of the ship side was experimentally studied, and the residual velocity was measured successfully. The comparison demonstrated that the values of the residual velocity obtained by simulation well agreed with the experimental results. The simulation indicated that the velocity of the SCJ decreased after penetrating the inner plate. Moreover, the influences of the ship side structural details, including the inner plate thickness, the distance between the inner and outer plates and the layout of the inner plate, on its protective ability against SCJ were investigated. The research indicated that increasing the thickness of inner plate and the spacing between inner and outer plates can effectively reduce SCJ residual velocity. Replacement of the inner plate with a multilayer plate could obviously reduce the SCJ residual velocity. The simulation method could describe the process of SCJ generation and penetration accurately, and the research results could provide references for the protective structural design of the ship hull attacked by SCJ.
Experimental Study on Asphaltene Deposition Characteristics in Yudong Block of Yingmaili Oilfield
Authors: Xu Hang , Zhou Fujian , Li Yuan , Zhu Liyan , Bai Hao , Yao Erdong
Published: October 2022

The oil wells in the Yudong block of Yingmaili area have encountered serious asphaltene deposition problems during production, which adversely affected the productivity of oil wells. Hence, it is necessary to carry out experiments to study the phase behavior of the well fluid and the characteristics of asphaltene deposition. Experimental research began with the preparation of simulated gas-bearing crude oil and the conduct of PVT tests. Then, the laser solid deposition analyzer was employed to study the asphaltene deposition characteristics of gas-bearing crude oil under reservoir conditions. Finally, differential scanning calorimetry experiment was carried out to measure the initial asphaltene precipitation temperature and quantitative characterization the deposition amount of the ground degassed crude oil. Results show that there are four phases areas of “gas-liquid-solid”, “gas-liquid”, “liquid-solid” and “pure liquid” for gas-bearing crude oil at different temperatures and pressures, and temperature is an important factor affecting asphaltene precipitation in Yudong oil wells. The initial asphaltene precipitation temperature of the surface degassed crude is 23.05 °C, with instantaneous deposition reaching a maximum of 0.01178 % at 6.2 °C and cumulative deposition reaching 8.34 % at −30 °C. This research provides a strong support for effectively overcoming the asphaltene blockage challenge in Yudong block.
FPSO Second-Order Roll Motions and the Impacts on SLWR Riser Design
Authors: Prado Vinicius G. , Senra Stael F. , Ferreira Marcos Donato A. S. , Oliveira Allan C. , Sena Bernardo D.
Published: October 2022

The dynamic behavior of risers is highly influenced by the FPU motions, due to the effects of the environmental conditions (waves, wind and current) on the hull. Representing the wave numerically by a velocity potential, we will assume that it can be expanded as a power series with respect to a parameter ε. The first order effects generate motions with the same frequency of the incident waves and are directly proportional to their amplitude. Second order effects generate motions with frequency equal to the difference (low frequency) or sum (high frequency) of the frequencies of the incident waves, treated as bichromatic in the numerical model, and are proportional to the product of the amplitude of each incident wave in this pair.

Significant second order motions are commonly observed in the horizontal plane (surge, sway and yaw), due to the low mooring stiffness. Recently, however, this phenomenon was also observed for roll motions in several new FPSOs that will operate in the Pre-Salt of Santos Basin. The phenomenon had already been detected in a deep draft semi-submersible from Campos Basin, but only more recently in FPSOs.

The new units have high roll natural periods, above the typical wave period range on the pre-salt region, but the roll response occurs with periods close to the natural period of the system and can be significant. In this way, sea states with incident waves in the Santos Basin typical period range (4 to 20 s) generate additional roll excitations and motions on the floater outside the incident range (above 20 s). This phenomenon was detected in model tests and confirmed by numerical studies.

This new FPSO behavior requires some care with how the risers and their interfaces will be studied. While 2nd order motions of surge, sway and yaw can impose a slow motion on the riser system due to their periods being typically well above 150 s, 2nd order roll motions are only slightly above 20 s, imposing displacements and accelerations that can directly affect the behavior of the riser top region.

This paper aims to present the joint effort of Petrobras’ Naval Architecture and Subsea Risers teams to properly represent this phenomenon in FEM time-domain riser analyses, as well as the most important issues observed and incorporated into the risers’ projects in terms of extreme combined load effects and wave&motion fatigue.
Simulation of Trawl Board and Pipeline Pull-Over Interaction
Authors: Longva Vegard , Levold Erik , Ilstad Håvar , Sævik Svein , Klæbo Frank , Finstad Opgård Marie , Arenfeldt Vilsen Stefan
Published: October 2022

This paper presents a finite element (FE) model for simulation of trawl board and pipeline pullover interaction. The considered trawl gear system is referred to as a single otter trawl. This system consists of a single trawl net, two trawl boards and a fishing vessel which are connected by steel ropes. The trawl net was modelled by a new simplified trawl net model ensuring high computational efficiency. This trawl net model can simulate the correct tension level in the steel ropes connecting the trawl net and the trawl boards during the pipeline interaction phase, which is crucial to obtain a realistic trawl board interaction behaviour. The trawl boards were modelled as 6-DOF rigid bodies which were assigned a tailormade hydrodynamic load model based on a 3-parameter interpolation scheme both for the added mass and the forward-speed induced loads. Compared to previous work, the applied interpolation scheme was extended and improved in terms of parameter choice and number of parameters. The forward-speed induced loads consist of drag and lift loads. These loads were estimated by flume tank testing considering numerous trawl board configurations in terms of angle of attack, board-seabed inclination angle and gap between the trawl board and the seabed. Detailed measurements of the trawl board applied in the flume tank test were done to obtain an accurate description of the contact geometry, the centre of gravity and the rotational mass properties. The proposed FE model was validated against model test results of trawl board pull-over considering variation of pipeline height, pipeline diameter and trawling velocity. The FE model was found to give very good agreement with the model test in terms of build-up of pipeline interaction forces, peak force level and duration. The FE model is therefore regarded as applicable for use in design analysis of pipeline and trawl board pull-over interaction.
Oscillation of a Flexible Catenary Shaped Submersed Pipe Induced by Two-Phase Slug Flow of Liquid and Gas
Authors: Silva Jéssica P. , Morooka Celso K. , Bordalo Sergio N. , Trigo Caio C. O.
Published: October 2022

In this paper, an experimental study of the excitation of a submersed suspended flexible pipe induced by the internal two-phase slug flow of liquid and gas is presented. The experiment was conducted with the pipe set in catenary configuration inside a water tank with a depth of 2m. Water and air were injected into the pipe at various flow rates combinations, leading to the formation of horizontal slug flow patterns. The slug two-phase flow generated intermittent loads on the pipe causing its oscillation. The dynamic response of the pipe to the slug flow was monitored by cameras which registered the movement of target marks set up along the body of the pipe. Processing the video images, we obtained the time-history of the movement of the pipe, and from this, the frequencies and amplitudes of motion were determined. With the proper scaling up, and in conjunction with computer simulators of pipe dynamics running intermittent load models of slug flows, the present work may be helpful to improve the capability of engineers for the analysis of the behavior of suspended risers used in offshore petroleum production carrying up oil and gas from petroleum reservoir wells to floating production facilities.
Energy Efficiency and Mitigation of Greenhouse Gases in FPSOs Ships
Authors: Castro Gustavo , de Barros Gallo Alexandre , Fossa Alberto José , Moutinho dos Santos Edmilson
Published: October 2022

Among the main opportunities reviewed and highlighted within the industry’s value chain, the upstream sector stands out and includes exploration and production activities for oil and natural gas, subdividing into key areas that concentrate a high demand for energy and, consequently, a relevant portion of emissions. A review and discussion about the FPSOs ships can be justified by market factors since ships currently comprise the main global offshore oil production systems. Among the highlights in the scope of emissions, the activity indexes are mainly composed of carbon dioxide (CO2) and methane (CH4), in addition to containing minimum levels of nitrous oxide (N2O). Whereas for emissions — which can occur either by combustion or by leakage or treatment processes — are divided and presented into four groups: Power generation (68% CO2 and 7% CH4), flaring (26% CO2 and 18% CH4), unintentional fugitives sources (0.02% CO2 and 22% CH4) and chemical ventilation (6% CO2 and 53% CH4). Although it still presents difficulties in operational implementation, the promotion of research and policies on the emission of greenhouse gases in the oil industry can help and enable the construction of a more secure, sustainable, and integrated energy future.
Human-Machine Engineering Virtual Simulation for the Wheelhouse on Large Ships
Authors: Li Chuntong , Wei Naikun , Luo Xiaomeng , Lv Jianjun , Yang Xuelian , Wang Deyu
Published: October 2022

The research of the wheelhouse ergonomic design for large ships is of great significance to minimizing wheelhouse human errors and guaranteeing the safety of ship navigation. To obtain a better human-machine engineering implementation effect and a faster feedback during the wheelhouse designing, the paper proposed a virtual simulation and evaluation method. First, based on anthropometry and relevant theoretical knowledge of human dynamics, the virtual crew database was built via 3dsMax, and task actions such as crew walking, operating buttons, and observation were defined. Second, the design requirements of ship wheelhouse human-machine engineering were summarized from an overall perspective. Subsequently, a virtual simulation of the working environment was implemented, while the layout and design of the wheelhouse structure were analyzed. Besides, the evaluation index system was constructed in an analytic hierarchy process. Finally, a digital integrated evaluation system was established to evaluate the man-machine interface design for the wheelhouse, including three-dimensional digitalization model, real-time virtual simulation and human-computer interaction design, which verifies the effectiveness of the proposed evaluation method. According to the corresponding profound evaluation result analysis, the suggestions for improvement were put forward.
Spatial Distribution of Impact Pressure Impulse on a Semi-Submersible in Irregular Waves
Authors: Zhang Nianfan , Xiao Longfei , Wei Handi , Teng Xiaoqing , Guo Yinghao
Published: October 2022

Semi-submersible platforms have been widely used in offshore oil and gas exploitation due to their excellent performance, but wave impacts in extreme sea states remain a major concern. For the design of offshore structures with sufficient structural capacity, scholars have pointed out the wave pressure impulse obtained by time integration is more crucial compared with the peak impact pressure. In this study, wave basin experiments were carried out under a series of irregular waves to study the spatial variations of pressure impulse on a semi-submersible. To capture more wave impact events and get more accurate local impact pressures, a large number of impact load measurement units were compactly installed on two adjacent surfaces at the corner of test model. The probability statistical method is adopted to analyze the nonlinear features and spatial variations. The results show that the pressure impulse on a semi-submersible in irregular waves has strong variability and its spatial distribution presents local concentration features. It is found that wave impacts on the column are more serious and the variations of pressure impulse on the column are greater than that on the side of deck box under head sea state. Spatial variations of pressure impulse on a semi-submersible are severely affected by significant wave height Hs and spectral peak period Tp of irregular waves. Meanwhile, the number of wave seeds used in model tests have a decisive influence on the estimation and spatial variation of wave pressure impulses. The perspectives given in this study may provide references for the structure design of semi-submersible platforms and lay a foundation for improving the laboratory experiment of wave impacts.
Casing Collapse Resistance Under Long-Term, Non-Uniform Salt Loading
Authors: Batruny Peter , Campbell Scott , Rahim Azral , Yun Thiam Yap , Yunus Syed , Lumley Pete , Suryanarayana Poodipeddi V
Published: October 2022

Collapse loads from uneven salt loading have been and remain a topic of discussion in the oil and gas industry. Studying this phenomenon requires large amounts of resources and risk for operators and casing vendors alike. As Oil and Gas exploration and development moves into deeper waters and more challenging conditions, novel ways of design need to be adopted to keep costs low and maintain well integrity throughout the well life cycle. Different methods and concepts from vendors, operators, and engineering consultants in casing design for long term salt loading have been reviewed and analyzed. A common Casing design software was used to analyze the different methods through modelling and load analysis with the subsequent results compared. A reliability-based design approach incorporating deforming casing dimensions and failure probabilities is proposed. A decision-making flow chart is also developed to avoid over-designing and safely optimize casing design for an exploration keeper-well. Reducing uncertainty of uneven salt loading on production casing will pave the way for more fit-for-purpose well designs. By doing that, less material surplus is generated resulting in less waste and less emissions.
Short-Term Extreme Response Prediction for a Jacket Platform Subjected to Nonlinear Wave Loads
Authors: Chai Wei , Yu Xiangpeng , Leira Bernt J. , Gu Jian
Published: October 2022

For bottom supported jacket platforms, the wave loads are generally nonlinear due to the drag-term in the Morison equation. As a result, the associated dynamical response for the offshore platform, such as the overturning moment and the base shear force, exhibit pronounced nonlinear characteristics. In this work, the dynamic response of the jacket platform is described by a single-degree-of-freedom (SDOF) model. The nonlinear wave load in the SDOF model is modeled as a polynomial of a filtered white noise. Subsequently, by application of the linear filter technique, the SDOF model is extended into a four-dimensional (4D) Markov dynamical system, whose probabilistic properties are governed by the corresponding Fokker-Planck equation. The path integration (PI) method is applied in order to solve the Fokker-Planck equation by taking advantage of the Markov property of the dynamical system. The response statistics calculated by the PI method are validated by Monte Carlo simulation (MCS). The statistical characteristics of the response for the jacket platform subjected to nonlinear wave loads are determined by means of numerical simulations. For the selected sea state, the mean upcrossing rates of the dynamical responses, i.e. the overturning moment and the base shear force, are employed to obtain the extreme responses of the jacket platform.
The Dynamic-Static Coupled Full Field Optimization of ICD/AICD Completion for the Pilot Wells Selection and Design in N Oilfield Middle East
Authors: Wu Bohong , Shi Shuzhe , Liu Jing , Wei Chenji , Li Yong , Li Baozhu , Lou Yuankeli , Yu Tao
Published: October 2022

Horizontal wells with open-hole completions are very common in N field Middle East, over 80% of the well completions are open-hole completions. However, in recent years’ production, some of the open-hole wells face several challenges from the perspective of reservoir management, such as early-stage water/gas breakthrough and inefficient drainage around the wellbore. These challenges are caused by the existence of high permeability streaks and the heel-to-toe effect. Therefore, aiming at these challenges, the present work proposed the lower completion strategy and established the lower completion workflow to implement inflow control devices (ICD) or autonomous inflow control devices (AICD) with packers, and selected some representative wells in N oilfield to find out the lower completion optimization results of the whole well life.

The principles of screening and selecting the pilot candidate wells in the N field middle east are operable, duplicable, and valuable. The pilot wells need to be the representatives in both geology and engineering, scheduled to be drilled recently and able to be evaluated from numerical simulation. For the comprehensive production analysis, the static model was used for sensitivity study and optimization and the dynamic model was used for the full-field assessment. The sensitivity and uncertainty of design parameters include compartment length, nozzle size, cross-section area and flow coefficient. Then, the static model was coupled with the dynamic model to obtain the optimal lower completion settings of the whole well life. The dynamic sector model that included injection wells and production wells was derived from a full field model. By using the optimized ICD/AICD parameters and deploying the tools correctly based on reservoir heterogeneity, the reservoir performance such as water cut, gas-oil ratio and cumulative oil production can be obtained to validate the optimization results. Several cases were studied to demonstrate the production improvement and economic values with the optimized lower completion. It is shown that the cumulative oil production will increase, the production plateau will extend and the overall NPV will be higher.

This work can give guidance to the selection of the most fit-for-purpose lower completion technology for different well objectives when facing different kinds of challenges.
Computational Study on the Transmission of COVID-19 Virus Inside a Ship
Authors: Huang Luofeng , Riyadi Seogeng , Utama I Ketut Aria Pria , Thomas Giles
Published: October 2022

To investigate the operational improvements of vessels under the impact of COVID-19, this work has developed a Computational Fluid Dynamics model combined with Lagrangian particles to study the airborne transmission of COVID-19 viruses inside a ship. Initially a generic model was established to enable validation against experimental results for the diffusion of flu virus in an idealised room. Following this, the room geometry was replaced by the superstructure of a full-scale crew boat. Considering the boat advancing in open water, simulations were conducted to study the particulate flow due to a person coughing and speaking, with the boat’s forward door open and closed. The results have shown that, when the forward door is open, a significant airflow can carry the viruses to make extensive contacts with the passengers. This led to the suggestion of keeping the door closed. However, when the forward door is shut, face-to-face speaking can generate viruses that can float in the air for a long time, and it was found that the viruses mainly stay within a half-meter distance in front of the speaking person, before sinking to attach to the deck. Thus, a social-distancing suggestion on seat arrangement has been highlighted to minimise the risk of contagion. Overall, this work is expected to inform guidelines on hygienic and reconfiguring means for operators to counter COVID-19 and potentially the spread of similar viruses in the future.
Rapid Assessment of Ship Bottom Grounding Damage Considering Combined Surge and Heave Motion
Authors: Pineau Jean-Philippe , Le Sourne Hervé
Published: October 2022

In most of the available literature in grounding analysis, the ship is supposed to run aground over a rock following a prescribed horizontal trajectory. However, in situations where the vessel is navigating in presence of waves, its oscillating heave motion sometimes leads to multiple breaches in the bottom plating, as observed in some real grounding events [1]. Recent numerical studies [2] showed that resulting overall damage of the hull can extend up to 4 times the one obtained by assuming only a horizontal movement for the ship.

Despite the increase in computing capacity of computers, nonlinear finite element simulations are very time consuming, and consequently not well suited for probabilistic damage stability analyses that may involve hundreds or thousands of grounding scenarios. In the present paper, a simplified analytical model based on plastic analysis is developed for the response of an unstiffened bottom plating, with the aim to rapidly assess the damage of a ship grounding on a rock idealised as an elliptic paraboloid. At the moment of impact, the ship is supposed to have both heave and surge velocities. Sliding and raking situations are considered and the criterion used to switch from one mode to the other is discussed. The model is then confronted to finite element simulations for different rock shapes, velocities, and friction coefficients. Although the proposed approach is shown to give a good prediction of the dissipated energy in most cases, some limitations are also highlighted.