bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Fatigue Crack Growth Rates Between Different Specimen Geometries
Authors: Zhang Yan-Hui , Doré Matthew 
Published: October 2021

Abstract
Most engineering components are subjected to cyclic loading in service and design against fatigue failure is often a key consideration in design. For fracture mechanics fatigue analysis, fatigue crack growth (FCG) tests are often required to determine the relevant Paris power law parameters for the material under the environment concerned. Standards allow use of different specimen geometries for FCG tests such as compact tension (CT), centre crack tension (CCT), single edge notch bend (SENB) and single edge notch tension (SENT). However, when selecting specimen geometry for fatigue crack growth rate (FCGR) testing, there is often doubt about which specimen geometry is more appropriate and whether they give similar FCGR. There is limited work to compare the FCGR between different specimen geometries.
This paper first briefly introduces the guidance on FCG test specimen geometries in standards and compares the advantages and disadvantages of these specimen geometries. A comprehensive literature review is carried out to compare the FCGR data between different specimen geometries. FCGR tests are conducted on SENB, SENT and CCT specimens of C-Mn steel to investigate any effects of specimen symmetry/asymmetry and crack constraint on FCGR. Based on the literature review and test data, it is concluded that FCGR is independent of the specimen geometries examined.
Early-Phase Offshore Hydrocarbon Field Planning Considering Environmental Factors and Using Integrated Asset Modeling
Authors: Moon Seok Ki , Stanko Milan 
Published: October 2021

Abstract
This work discusses methods to quantify environmental indicators of development alternatives during the early design phase of offshore fields and how to include them in the selection process.
The goal is to develop a decision-support method to: 1) evaluate field development alternatives of reduced environmental impact and 2) dealing with conflicting indicators such as economic value and environmental performance. A value chain model of a synthetic field located in the Norwegian Continental Shelf (NCS) was created using an integrated asset modeling tool. The model computes the net present value (NPV) of the project and the amount of CO2 emissions based on the hydrocarbon production profile and the field energy consumption.
Several cases and field development power supply alternatives such as open-cycle gas turbine (OCGT), combined-cycle gas turbine (CCGT), power from shore and offshore wind farms are analyzed. It has been assumed that the gas turbine generates most of the CO2 and that the amounts of CO2 produced is a function of the field power consumption. The effect of the CO2 tax is included and studied.
Results show that there are development alternatives that provide fair economic value while having low CO2 emissions. For the cases studied, the solutions with gas turbines have higher economic value than the solutions with power from shore and offshore wind farms, but emit large amounts of CO2. For solutions using gas turbine, a combined-cycle has less CO2 emission intensity (kgCO2/boe) than open-cycle, however, the energy intensity (kWh/boe) depended mainly on the amount of gas recycled and is highest for 75%. These indicators could allow field planners to evaluate and compare different field development concepts. Breakeven values of CO2 tax were determined for which the economic value of development with the gas turbine is equal to that of development with power from shore or offshore wind farms.
Fatigue Reliability-Based Inspection Planning Methodology for Corroded Mooring Chain Links
Authors: Rezende Filipe A. , Simão Marina L. , Gomes Ricardo S. , Videiro Paulo M. , Sagrilo Luis V. S. 
Published: October 2021

Abstract
Mooring systems are responsible to limit the offsets of oil and gas floating production systems due to environmental actions. Therefore, they are extremely important for the overall safety of the floating unit and of the risers system connected to it. Mooring lines are subjected to pre-tension and environmental loads effects and must be designed to comply with the ultimate, accidental and fatigue limit state criteria. In general, floating units mooring lines are composed by a top chain segment, a rope segment, and a bottom chain segment. Most of the accounted failures in mooring lines are related to fatigue damage in the chain links of the top or bottom segments. Material degradation due to corrosion effects plays an important role in this failure mechanism.
Engineering practice usually recommends that a constant corrosion rate model is to be adopted in the design. Periodic inspections are to be carried out in the mooring lines in order to assess the corrosion effects and other issues during the operational life of the floating system. However, corrosion is a complex phenomenon, which behavior is difficult to predict. Adopting a deterministic corrosion rate can lead to non-realistic results, compromising the system safety and the inspection planning.
Therefore, to consider the problem uncertainties and comply with standards guidance, this work proposes a time-dependent fatigue reliability-based method to update the inspection planning using the results of previous inspections. The method is applied in a case study of a corroded chain segment of a mooring line, assuming a continuously-updated corrosion rate model and the S-N curve fatigue approach.
Results show that the proposed method, based on solid safety assumptions, is a feasible and more reasonable way to define inspection dates, avoiding the mooring system to operate in unacceptable levels of risk.
Finite Element Analysis of a Flexible Pipe Interlocked Carcass Under Tension Loads
Authors: Geremias Toni Fernando , Provasi Rodrigo , de Arruda Martins Clóvis 
Published: October 2021

Abstract
To correctly model the structural behavior of a flexible pipe, the contribution of all the layers must be completely understood, among them the interlocked carcass. That carcass is a metallic layer designed to provide radial stiffness to a flexible pipe, mainly supporting pressure differentials and thus preventing failure modes such as collapse and crushing, but its behavior under other loads is worth of investigation. This paper contributes to understanding the carcass behavior under tension. Given its complex helical and interlocked geometry, modelling the carcass through the Finite Element Method is a challenging task, not only due to the large size of the models, but also due to the nonlinearities and convergence difficulties that arise from the self-contacts at the interlocking. For these reasons, most works developed over the past decades have adopted an equivalent layer approach, in which the carcass is replaced by an orthotropic cylindrical layer with equivalent mechanical properties. Although practical, this approach disregards the effects from the interlocking, such as stiffness variations and stress concentrations. Therefore, aiming a more realistic representation and a better understanding of the mechanical behavior of the interlocked carcass, this work presents four different carcass finite element models to analyze this layer under tension loads. The first one is a complete three-dimensional finite element model of an interlocked carcass discretized with second order isoparametric solid elements and surface-to-surface contact elements. The second model consists of a version of the first one with the addition of an inner polymeric sheath. As for the third and fourth models, it was adopted the simplifying ring hypothesis, that is, a carcass with 90 degree lay angle, thus allowing the axisymmetric modelling of the two previous configurations, representing a substantial computational gain by using two-dimensional meshes. The results of those models are then presented and compared, and the validity of the adopted simplifying hypothesis is verified.
Pitting and Corrosion Rates of Coated, Uncoated, and Insulated A333 Steel Pipelines in Marine Harsh Environment
Authors: Hillier Alan , Khan Faisal , Caines Susan 
Published: October 2021

Abstract
Pipelines are one of the most economical and safe means of transporting useful materials, and their design life depends on protection mechanisms present. Marine environments increase corrosion rates due to moisture, and elements like chloride which increase localized pitting rates. Thirty-six A333 low temperature carbon steel pipelines were placed at Argentia, NL, an extremely corrosive environment (C5) near high tide mark. The experiment consisted of coated, uncoated, and insulated pipes. Exposed for a period of two years, corrosion rate, optical inspections, and pit depth were recorded at intervals. The highest average pit and maximum pit depth occurred in uncoated insulated pipes and coated uninsulated pipes. The highest average mass loss occurred in uncoated (insulated and uninsulated) pipes. The least mass loss and pit depths generally occurred in coated pipes (both insulated and uninsulated). Corrosion near the ends of the pipes were more significant than other locations. Final averaged corrosion rates for insulated coated and uncoated pipes, were 0.017 and 0.021mm/yr respectively. Corrosion rates for uninsulated coated and uncoated pipes, were 0.014mm/yr and 0.023mm/yr respectively. Maximum and mean pit depths for insulated coated and uncoated pipes were, 180/156 and 256/205 microns, respectively, while for uninsulated coated and uncoated were 210/177 and 182/148 microns, respectively. Some coated and uncoated insulated pipes had negligible pitting and corrosion. Results provide an increased understanding of corrosion rates, corrosion under insulation corrosion, and under coating, and pitting data for pipelines in service in marine harsh environments.
Plug and Abandonment Trends in Albertan Gas Wells
Authors: Trudel Elizabeth , Bizhani Majid , Frigaard Ian 
Published: October 2021

Abstract
Alberta is known to be a significant oil & gas producer with over 468,000 wells drilled in the province since the beginning of the twentieth century. While the majority of these wells were drilled to produce oil, approximately 165,000 gas wells can be found in Alberta and are studied here. This represents a more than six-fold increase over Alberta’s western neighbor, British Columbia, which is known to be a primarily gas producing province. Over 80% of the gas wells in Alberta have yet to enter the abandonment stage. A growing stock of suspended wells can be found in the province which comes with an increase in liability for all parties involved i.e., the operators, the provincial regulator and the Orphan Well Association (OWA). Here we analyze abandonment trends in Alberta, showing that combining the growing suspended well stock with the shorter lifetime associated with the horizontal gas wells currently being drilled in the province, we can expect a wave of well abandonments in the coming decades. We focus only on gas wells, where we can make a comparison with a similar study previously conducted for wells in British Columbia.
Effect of Marine Nuclear Reactor Environment to Ship’s Structural Responses
Authors: Jeong Han Koo , Kim Soo Hyoung 
Published: October 2021

Abstract
As the regulations on greenhouse gas emissions at sea become strict, technology development to minimize environmental pollutants emitted from the propulsion system of ships is actively underway. Research on the use of renewable energy as a power source of ships propulsion system pursuing eco-friendliness is continuously carried out. However, considering the recent development of ships’ large-scale, and at the same time minimizing greenhouse gas emissions at sea, the interest in nuclear energy as the means of a stable supply of environmentally friendly large-capacity energy has been increased. In this study, the effect of marine reactor operation on the material properties of a ship hull material is reviewed, and from this, hull structural behaviors are investigated. Attention is paid to the neutron irradiation on the material in the reactor operation environment, and then the strength assessment of a hull structural member assumed in the neutron irradiation situation is performed. Considering the neutron irradiation effects, the Young’s modulus, poisson’s ratio and allowable stress of DH36, typical high tensile strength steel used in ship hull, are varied based on the research findings related with the topic of neutron irradiated steels. Rectangular stiffened plated structures, basic common structural members for ship hull, are exemplified for the strength assessment to understand their structural behaviors such as strength and stiffness. Results from this study provide information on the effect of neutron irradiation on the hull structural behaviors of the ship using nuclear power and possibly can supplement the hull structure part from classification societies’ rules and regulations.
PyraWind™: An Innovative Floating Offshore Wind Turbine (FOWT) Global Performance Analysis
Authors: Yang Zhiyong , Bian Xiaoqiang , Shi Yu 
Published: October 2021

Abstract
In the near future, the offshore wind industry will experience a significant increase of turbine size and of floating wind development activities. A floating offshore wind turbine foundation offers many advantages, such as flexibility in site selection, access to better offshore wind resources, and quayside integration to avoid a costly heavy lift vessel offshore campaign. PyraWind™ is a patented three canted column semisubmersible floating foundation for ultra large offshore wind turbines. It is designed to accommodate a wind turbine, 14 MW or larger, in the center of the interconnected columns of the hull with minimal modifications to the tower, nacelle and turbine. The pyramid-shaped hull provides a stable, solid foundation for the large wind turbine under development. This paper summarizes the feasibility study conducted for the PyraWind™ concept. The design basis for wind turbine floating foundations is described and the regulatory requirements are discussed. Also included are the hydrodynamic analysis of the hull and ongoing work consisting of coupling hull hydrodynamics with wind-turbine aerodynamic loads. The fully coupled system was analyzed using OpenFAST, an aerodynamic software package for wind turbine analysis with the ability to be coupled with the hydrodynamic model. Due to the canted columns, a nonlinear analysis was performed using the coupled numerical hydrodynamic model of the platform with mooring system in extreme sea states.
Validation of a Simplified Transient Multiphase Flow Model for Any Pipe Inclination With Gulf of Mexico Field Data
Authors: Tornisiello Ligia , Xavier Teles Francisco Bruno , Waltrich Paulo J. 
Published: October 2021

Abstract
This paper presents a simplified model for transient two-phase flow in pipes of any inclinations, for slow transients. Such simplified model facilitates its use for real-time monitoring and machine leaning implementations.
An improved correlation for the drift flux parameters is adopted in the model, which enables the utilization of the model for simulating transient flow scenarios for any pipe inclination and extends its applicability to a wider range of conditions. From the formulation, an equation has also been proposed to quantitatively define the application of the concept of slow transient. This equation indicates if a case of interest can be classified as a slow transient, which consequently implies that the use of the proposed model would likely provide accurate results.
The model has been validated with experimental and field data, and also compared to the state-of-the-art commercial simulator for transient two-phase flow in pipes. The results showed an agreement within the range of ±30% for the holdup predictions for 65% of the scenarios, and an agreement within the range of ±30% for the pressure predictions for 82% of the scenarios considered in the validation data set. The model performance evaluation with data from a well in the GOM showed a maximum error of 30% in terms of predicted bottomhole pressure and an average error of 9% for the simulation of two years of transient flows.
A Prediction Model of Wellbore Temperature Based on Hydration Kinetics During Well Cementing in Nature Gas Hydrates
Authors: Xue Yucheng , Lu Haoxin , Wang Chengwen 
Published: October 2021

Abstract
Stability of nature gas hydrates (NGH) is greatly impacted by temperature. Because intense heat is released from cement hydration during well cementing, limiting the temperature rise of cement is critical for safe cementing of NGH well. The total heat release by cement slurry has a strong correlation with the mechanical properties of cement slurry. Consequently, reducing the heat of hydration of cement means typically results in lower strength of the cement stone. Traditional evaluation methods do not fully consider the complex interaction between cement hydration reaction and heat transfer in the wellbore, therefore, it is difficult to determine whether the cement slurry formula selected is suitable for well cementing in nature gas hydrates. In this paper, a model to predict cement wellbore temperature was developed by incorporating the complicated interactions between temperature and cement hydration reaction. The model established the relationship between degree of cement hydration and wellbore temperature based on the cement hydration reaction kinetics. Coupled with differential method and numerical calculation, the influence of wellbore temperature on NGH was analyzed during the cementing process. The newly developed model was used to predict the field performance. Model predicted data and field data are within 10.0%. By accurately predicting the change of NGH with wellbore temperature during the cementing process, the model in this paper can not only effectively guide the research and development of low hydration heat cement slurry for NGH well but also find and avoid safety hazards in time during the design process of NGH cementing slurry.
Strength Prediction of Connector Structure of the Double-Module Semi-Submersible Platform
Authors: Minggang Tang , Ziyuan Wang , Chun Xu , Shengpeng Li , Yuchao Chen , Xinyun Ni 
Published: October 2021

Abstract
A double-module semi-submersible platform for scientific experiment has been applied firstly in practical engineering. Hinge-type connectors are used to link the two modules reliably and release the relative pitch freedom, and the strength of connector structures determines directly the integrity and safety of the platform. In this paper, the three-dimensional finite element model of the platform structure is developed including the local features of connectors, and main elastic modes are obtained. By using the Potential flow theory and the Green Function method, the hydrodynamic coefficients of the model are determined. Based on the three-dimensional hydroelastic theory, the response amplitude operators (RAOs) of generalized coordinates associated with different order modes are investigated. That indicates the structural deformation of connectors is excited mainly by modes of horizontal bending moment and torsion, and the stress responses in the longitudinal bulkheads close to bearings are generally marked. Using the modal superposition method, the RAOs of stress in the typical joints of connector structures are calculated under the given wave directions. Considering the JONSWAP spectrum and the amplitudes of stress responses of connector structures following Rayleigh distribution in short term, the strength of the connector structure is predicted in short term. In order to verify the correctness of the strength prediction method presented in this paper, more than thirty stress sensors are installed on the typical joints of connector structures of the double-module semi-submersible platform located in the real sea. Those stress responses are monitored during the typical typhoon activity, and the statistical data is compared with the predicted results from the theoretical model. Both the distribution trend and magnitudes of the results from the two methods are principally consistent that validates the given model. This theoretical method may provide an effective tool to analyze the strength of connector structures of multiple-module offshore platform.
Optimization and Evaluation of Chemical Shrinking Agent for Deposits in Salt Cavern Gas Storage
Authors: Ran Lina , Liu Shuang , Wanyan Qiqi , Yao Erdong , Bai Song 
Published: October 2021

Abstract
Salt cavern gas storage is an important strategic method to shave the fluctuation of supply-demand of natural gas in China. However, due to low grades of salt beds, there remains lots of insoluble sediments accounting for 1/3 up to 2/3 of the storage capacity at the bottom of cavity. The use of chemical agent with the function of swelled-clay-shrinking is an effective method for enlarging actual cavity volume. Clay swelling and physical deposits experiments were conducted to select the suitable chemical shrinking agent and study the relation between salt rock and agent. A device simulating the leaching process of insoluble sediments was developed to evaluate different factors on residue deposits and XRD (X-Ray Diffraction) was used to analyze mineral compositions of various salt caverns. The results showed that the main controlling factor for the volume swelling of the bottom insoluble sediments in the salt cavity is the electrostatic repulsion. These hydrated cuttings carry a negative charge leading to the electrostatic repulsion between each other, which promotes the loose accumulations of these physical deposits. The relation between rock and shrinking agent is clarified and the selected chemical agent has an excellent adaptation in salt cavern gas storages through the tests above. In addition, the result provides an experimental basis for minimizing the volume of the salt carven sediments to store more natural gas.
A Comparison of Inverse Models for the Estimation of Ice-Induced Propeller Moments on a Polar Vessel
Authors: Nickerson Brendon M. , Bekker Anriëtte 
Published: October 2021

Abstract
Full-scale measurements were conducted on the port side propulsion shaft the S.A. Agulhas II during the 2019 SCALE Spring Cruise. The measurements included the shaft torque captured at two separate measurement locations, and the shaft rotational speed at one measurement location. The ice-induced propeller moments are estimated from the full-scale shaft responses using two inverse models. The first is a published discrete lumped mass model that relies on regularization due to the inverse problem being ill-posed. This model is only able to make use of the propulsion shaft torque as inputs. The second model is new and employs modal superposition to represent the propulsion shaft as a combination of continuous modes, resulting in a well-posed problem. This new model requires the additional measurement of the shaft rotational speed for the inverse solution. The continuous model is shown to be more consistent and efficient, which allows its use in real-time monitoring of propeller moments.