bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation of Well Cement Integrity in Abandoned Oil and Gas Wells
Authors: Thaika Muhammad A. , Hu Ke , Kuru Ergun , Li Huazhou , Iremonger Simon , Lin Zichao , DeBruijn Gunnar 
Published: August 2024

Abstract
This research is focused on testing the limits of cement abandonment plugs, evaluating their isolating capabilities under severe conditions. The results will be used to understand possible failure modes and ensure long term effectiveness of wellbore abandonment operations of different cement systems.
In this study, small-scale bulk cement and abandonment plug (i.e. cement in casing) samples were optimally cured under 50°C and 1000 psi for a period of 7 days and tested for their permeability to understand the basic behavior of the cement. Water and Nitrogen permeability tests for all small-scale samples were conducted using a typical core flow setup.
A set of permeability experiments were also carried out using a physical wellbore simulator, which allowed cement curing and subsequent permeability testing under elevated pressure and temperature. The setup is designed to simulate abandoned wellbore section with variable fluid injection pressure, confining pressure and temperature conditions. Cement shear bonding strength was also determined after each experiment.
From the small-scale experiments, it was observed that bulk cement on its own had exceptionally low permeability. The small-scale abandonment plug exhibited relatively higher permeability than the bulk cement. Nitrogen flow was observed in the small-scale abandonment plug experiments, possibly through the cement-casing interface.
Two different cement blends were tested using the wellbore simulator; Neat G cement without any additives and a Class G cement with additives that has been engineered to enhance its sealing performance.
The wellbore simulator experiments had shown that the Class G plus additives cement plug outperformed Neat G cement blend in every testing scenario. Although both cement systems were tested in severe conditions, both performed adequately.
The class G plus additives cement blend also resisted the formation of a micro annulus better than the Neat G cement. Results also indicate an inverse relationship between the shear bond strength of the cement plug and the permeability of the cement system, indicating that stronger mechanical bonding also delivered improved resistance to gas flow.
Data measured from these experiments will form the baseline for future experiments where other crucial parameters are to be investigated.
A Monte Carlo Based Model for Estimating the Reliability of Offshore Structures Exposed to Environmental Loading
Authors: Zeeberg Allan Rod , Tychsen Jesper , Nielsen Jørgen Svejgaard , Cholley Jean-Marc 
Published: August 2024

Abstract
In Denmark, as in many other countries, there is a legal requirement to ensure that risks related to health and safety and major environmental incidents in connection with offshore oil and gas operations have been identified, assessed, and reduced to a level as low as reasonably practicable (ALARP). One aspect of this involves determining the annual structural probability of failure for safety and environmental critical elements (SECEs) on offshore installations exposed to environmental loading. This is achieved by employing Structural Reliability Analysis (SRA). New knowledge about breaking waves has surfaced during the last decade which adds complexity to the SRA procedure. An SRA using crude Monte Carlo simulation considering breaking waves is described in this paper. The developed models are validated against physical model tests and other simulation methods. The process is complicated as numerous sources of uncertainty (both aleatoric and epistemic) are included. The aim has been to determine failure rates reflecting, as close as possible, the actual probability of failure (also denoted “actuarial”) by minimizing the epistemic uncertainties, as opposed to previous work, where, due to inadequacies in the various models, the failure rates were “notional”. The reader is provided a general overview only without going into details on the individual models due to the extent and complexity of the models.
Static and Fatigue Analysis of Wind Turbine Towers Made in Composite Materials
Authors: Petiteau Jean-Christophe , Paboeuf Stéphane , Al-Ghuwaidi Abdulelah 
Published: August 2024

Abstract
In the context of the increase of the energy demand, the offshore wind industry is developing larger floating platform to produce more electricity and to minimize the levelized cost of energy (LCOE). The target is to install 20MW power turbine and more at sea, but the size of the platform, of the tower and of the turbine will significantly increase. The change of scale will lead to huge dimensions and heavy weight that will contribute to an increase of the cost for the installation and for the mooring. A solution to reduce the weight of the structure of Floating Offshore Wind Turbine (FOWT) has been investigated within the European Research project FIBREGY and consists in replacing steel by composite materials. The overall objective of the FIBREGY project is to enable the extensive use of Fibre Reinforced Plastic (FRP) materials in the structure of the next generation of large Offshore Wind and Tidal Power (OWTP) platforms.
This paper aims to present the results obtained for FOWT towers made in carbon fibres. Firstly, the calculation methodology developed during the FIBREGY project to evaluate loads applied to a FOWT will be detailed. This methodology is based on Bureau Veritas software programs and particularly on OPERA, a hydro-aero-mooring coupled dynamic calculation tool. Then, numerical simulations performed with ultimate loads in static and cyclic loads for the fatigue analysis will be detailed. Stresses will be compared with criteria determined within the project for such application as well as the fatigue life. Finally, the design of tower will be optimised in considering the damage in fatigue, the static stresses, the maximal deflections and the buckling.
An Optimized Consideration for Catenary Mooring System Designs
Authors: Cao Jianchun , Bhandari Anil , Galagoda Mahi 
Published: August 2024

Abstract
Catenary mooring systems have been widely used in offshore industry when oil and gas exploration and production was conducted in shallow to deep water. To ensure a catenary mooring system arrives at the seabed horizontally, a very long seabed anchor chain is usually used. In actual applications, a substantial length of anchor chain could be saved if a small load angle at Touch-Down Point (TDP) can be considered in the design. This paper first reviews the chain-soil interaction analysis model from previous studies. Based on this, an excel spreadsheet tool to simulate the behavior of chain-soil interaction has been developed. Then, the chain’s configuration in soft clay is investigated using the developed tool. The influence of a small load angle at TDP on the embedded chain length in soil and the influence of a load angle at TDP on the padeye load or load components are checked. Finally, a recommendation is made to improve (or optimize) the traditional design concept of a catenary mooring system (i.e., no uplift load at TDP for any stage) by considering a small load angle at TDP (i.e., 1° – 5°) for the intact and damage conditions under the maximum design environment (i.e., extreme design loading cases).
The Coupling Mechanisms of Seepage and Heat Transfer in Rock Fractures in Enhanced Geothermal Systems Based on the Lattice Boltzmann Method
Authors: Su Wei , Wang Zhiliang , Li Miao , Shen Linfang 
Published: August 2024

Abstract
The coupling mechanism of seepage and heat transfer in high-temperature rock fractures controls the heat extraction ability of enhanced geothermal systems. Utilising the lattice Boltzmann method, a numerical model is proposed to capture this coupling, accounting for fluid temperature’s influence on kinematic viscosity and thermal diffusion coefficient in rough fractures. The model’s validity is confirmed through a classic example. The effect of rough fracture surface on the coupling mechanism of seepage and heat transfer was analysed. The relationship between the roughness of the fracture surface and the performance indicators of geothermal extraction was discussed. The results show that neglecting the roughness of the fracture surface would lead to a severe underestimation of water temperatures within the fractures. As the roughness of the fracture surface intensified, its thermal breakthrough time gradually increased while the heat recovery rate and heat production power decreased.
Forced Vibrations of Cold-Water Pipe for OTEC Based on Generalized Integral Transformation Technique
Authors: Tan Jian , Zhang Yu , Zhang Yulong , An Chen , Duan Menglan , Sun Le 
Published: August 2024

Abstract
This paper investigates the forced vibration and stability performance of cold-water pipe (CWP) for Ocean Thermal Energy Conversion (OTEC) under different types of loads and boundary conditions. The vibration control equation of the pipe is derived considering viscoelastic dissipation, damping ratio of surrounding environment, mass ratio, and gravity parameter. The generalized integral transform technique (GITT) is applied to solve the vibration control equation and obtain the critical flow velocity and mode shapes of the pipe. The effects of damping ratio, viscoelastic coefficient, mass ratio, gravity parameter, and load types on the vibrational characteristics of the pipe are analyzed. The results show that the critical flow velocity of the pipe is sensitive to the boundary conditions and the parameters of the pipe and the fluid. The damping ratio and the viscoelastic coefficient can effectively change the stability of the pipe. The mass ratio and the gravity parameter have complex influences on the critical flow velocity, depending on the boundary conditions and the load types. The proposed method and results can provide guidance for the preliminary design and optimization of CWP for OTEC systems.
Basic Research on Seabed Visualization Technology Applying UV-Laser
Authors: Ishibashi Shojiro , Okada Takamitsu 
Published: August 2024

Abstract
Recently, in order to efficiently explore seabed resources using underwater vehicles, researches on effective technologies to visualize the seabed have been conducted. Underwater laser scanners have been proposed as one of effective methods that combine good measurement range and accuracy. An underwater vehicle equipped with an underwater laser scanner emits a laser and detects the reflection on the seabed to visualize the seabed topography with high precision. The characteristics of seabed reflection is difference depending on laser wavelength. Conventionally, visible lasers of blue to green wavelengths, which have good underwater propagation properties, have been used. Currently, we are currently working on a new underwater laser scanner that applies an invisible ultraviolet (UV) laser. It is expected that by understanding the underwater propagation properties of invisible laser and effectively detecting the laser reflections from the seabed, some unique state quantities of the seabed might be extracted. The new underwater laser scanner that uses UV wavelengths laser has been developing and its basic performance and effectiveness were verified in an actual deep seabed environment.
Offshore Wind-To-Hydrogen: the Impact of Intermittency on Hydrogen Production and Transport
Authors: Summers Eoghan , Race Julia , Mignard Dimitri , Tian Mi , Almoghayer Mohammed Alaa 
Published: August 2024

Abstract
Offshore wind is a promising renewable energy source for green hydrogen production, providing a versatile solution for energy storage and power-to gas concepts. This research investigates how the intermittent nature of offshore wind impacts the components of an offshore wind-to-hydrogen system. Proton exchange membrane electrolysers are frequently identified as being best suited to integration with intermittent renewables. However, stop-start cycling of current from a variable power supply can damage electrodes and reduce electrolyser lifetime. Therefore, a small current is required during no wind periods to prevent electrolyser degradation. An intermittent offshore wind resource can also impact pipeline transport of hydrogen. Variable hydrogen production leads to fluctuating hydrogen flow in pipelines. The resulting pressure variations, combined with the potential occurrence of hydrogen embrittlement in steel pipelines can increase the potential and severity of fatigue crack growth, thereby impacting pipeline integrity. Careful selection of pipeline materials and buffer storage to smoothen gas flows, can mitigate these potential impacts. This research proposes a configuration for hydrogen production on an offshore platform from a floating wind farm. It uses battery and hydrogen storage offshore to provide buffers, mitigating the potential impacts of intermittency on each component of the offshore wind to hydrogen system.
Vibration and Fatigue Mitigation of a 5 MW Barge-Type Floating Offshore Wind Turbine Under Misaligned Wind and Wave Loadings
Authors: El Hamoud Riad , Alkhoury Philip , Aït-Ahmed Mourad , Soubra Abdul-Hamid , Schoefs Franck , Dib Rabih 
Published: August 2024

Abstract
This paper aims at investigating vibration suppression and fatigue mitigation of a 5 MW barge-type floating offshore wind turbine (FOWT) under misaligned wind and wave loadings. A passive omnidirectional tuned mass damper (TMD) installed in the floating platform was employed. The aero-hydro-servo-elastic coupled simulation program for wind turbines, OpenFAST, was used to perform the numerical simulations. The omnidirectional TMD was tuned to the platform pitch and roll natural frequencies in order to mitigate the vibration and fatigue loads in fore-aft and side-side directions respectively. The TMD damping ratios in fore-aft and side-side directions were obtained from two minimization procedures where the objective functions are the standard deviations of platform pitch and platform roll motion respectively. The effectiveness of the omnidirectional TMD was checked for one load case under three misalignment angles (0° ; 45° ; 90°). The percentage change of the standard deviation (SD) and damage equivalent moment (DEM) between the controlled and the uncontrolled cases were used as indicators of vibration suppression and fatigue mitigation respectively. The obtained results have shown that the omnidirectional TMD can effectively mitigate vibrations and fatigue of the FOWT under misaligned wind and wave loadings. For instance, the reduction in SD of platform pitch and DEM of tower base fore-aft moment could attain 47% and 31% respectively in the case of a misalignment angle between wind and wave of 90°. Moreover, a comparison with an equivalent dual TMD was carried out. It was found that the omnidirectional TMD provides better bidirectional vibration and fatigue mitigation when compared to the dual TMD.
The Proposed Long Island Project in Singapore, is there a More Sustainable Way?
Authors: Lim Soon Heng 
Published: August 2024

Abstract
The Singapore Government recently announced plans for an 800-hectare reclamation on Long Island, south of East Coast Park. The announcement came under the scrutiny from city planners, and the academia as well environmental scientists, and NGOs. The government is seeking inputs from those who have interests. The multi-year in-depth feasibility study will commence in 2024.
Several alternatives are possible. The government’s proposal is essentially an 800-hectare polder. Between the existing shoreline and the landward side of the reclaimed land a large strip serves as a catchment for freshwater fed by monsoon rain.
This paper proffers a solution using a series of gravity-based caisson (GBC) modules to form a lagoon separating the freshwater from the seawater. They can be manufactured offsite, launched and towed to its final position where it is aligned and ballasted with seawater. Some of the GBCs are designed to accommodate floating gates which when partially raised by deballasting allows excess water in the lagoon to be discharged into the sea. The top deck of the GBC is designed as a roadway for light vehicles.
Within the lagoon, floating platforms serve as foundations for residential and commercial buildings and for recreation parks or as dormitories for students in nearby institutions of higher learning. Transportation may be by ferries, flying taxis (such as the EH216-S) or buses similar to Vaporetto in Venice. Floating electric bicycles would be a personal mobility option. There will not be any roads or drains to build or maintain. Floating bridges link key points to the mainland or the caisson roadways. Small barges ply the lagoon to collect garbage and floating debris which are mechanically transferred to a larger barge outside the lagoon for transport to incinerators. There will not be any roads or drains to build or maintain.
Why would a government consider this proposal when a major source of its income is leasing land? First, it is a greener option. Second, the capital outlay will be a fraction of the cost of land reclamation (estimated at SGD 6.4 billion). Third, the seaspace can also generate a source of revenue. At the end of the lease the plot can be freed up in a short time frame (by the owner), freeing up the plot for another investor to lease.
Maintenance of reclaimed land is costly as experience at the Kansai Airport and Jumeirah Island has shown. Foundations for land-based buildings take more money and time to complete. Buoyancy is a principle of physics independent of the soil properties below.
Extreme Value Analysis - Statistical Inference Method for the Identification of Most Probable Extremes in Highly Nonlinear Systems. Case Study: Green Water Loads on FPSO
Authors: Gkikas Georgios 
Published: August 2024

Abstract
This work aims at deriving the most probable extreme response of highly nonlinear systems under random excitations based on a collection (ensemble) of small size samples by using order statistics in combination with non-parametric statistical inference methods (SIMs). The resulting scheme essentially consists of the r-largest Order Statistics (r-LOS) model and the (Delete-d) Jackknife or Bootstrap non-parametric, resampling methods. Using the r-LOS model when dealing with relatively small size samples, more information from the collected set of extremes per sample can be accrued as opposed to the common engineering practice of employing just the single highest extreme per sample, i.e., Block-Maxima approach.
On the other hand, SIMs, with the aid of resampling with or without replacement, can further enhance this information using artificially created ensembles. As a result, from the ensembles produced via resampling, quantile levels and distribution parameters such as shape, scale and location become new random variables. With the aid of these new distributions, the probability of extremes can be explained better in terms of both sample size, i.e., number of realizations and number of largest extremes per sample.
Due to data availability, a direct application-example for the illustration of the merits of this novel approach is the determination of the most-probable maximum of experimental green water related extreme loads. Using the proposed approach, the statistical attributes of recorded extremes and distribution-fit parameters can be assessed w.r.t:
a. the number of realizations,
b. the number of largest extremes per realization,
c. all possible combinations of a and b.
An Innovative Testing Method to Qualify Deep-Water 66kV Power and Hydraulic Combined Umbilical
Authors: Zhou Ying , Wang Xu , Chen Kai , Shi Luhao , Yuan Yanyan , Zhang Dayu 
Published: August 2024

Abstract
With the development of deep-water offshore oil & gas and the extensive application of subsea high-voltage equipment, integration of 66kV power cable into umbilical will become a trend. With the increasing water depth of oil & gas field development, how to verify the reliability and safety of the 66kV power and hydraulic combined umbilical for deep-water application is a topic worthy of discussion. An innovative testing method is proposed, which incorporates mechanical tests in API 17E and type test in IEC 63026 on a single testing sample. The main purpose of the test is to verify the performance of the umbilical taking into account high voltage and deep water characteristics.
An innovative 66kV power and hydraulic combined umbilical was designed and manufactured, and subjected to a series of tests based on the testing method proposed in this paper. The results show that the designed umbilical performs well and the testing results are more conservative. The proposed testing method can provide a reference for the validation of high voltage power cable integration umbilical for deep water applications in the future.
Wind Turbines and Hydrogen-Based Energy Storage Hub Concept for Offshore Oil and Gas Platforms in the Norwegian Continental Shelf
Authors: Damaceno Daniela S. , Treider Thomas , Svendsen Harald 
Published: August 2024

Abstract
The Norwegian government has the ambition to decarbonize the offshore petroleum sector while retaining its international competitiveness. Considering that individual electrification of platforms from shore is both inefficient and expensive, the centralization of the heat and power generation at an offshore hub is thought to have the potential to be an energy and cost-efficient solution. This paper aims to develop an innovative cost-efficient concept for a clean offshore energy hub for supplying low-carbon heat and power to existing offshore oil and gas cluster. The simulations were performed using Oogeso, an optimization tool used to study the optimal operation of offshore energy systems. In summary, the concept is based on an offshore wind farm supplying a cluster of offshore platforms, with energy storage, electrolyzer, and fuel cells added to smooth out fluctuations in wind power. Two different variations of this concept are analyzed and compared by evaluating metrics such as wind power curtailment and hydrogen usage. The results have shown that a hybrid system using renewable energy sources can successfully power a cluster of offshore oil and gas platforms.
Non-Destructive Measurement of Residual Stress in the Carcass Layer of Marine Non-Bonded Flexible Risers Using X-Ray Diffraction Method
Authors: Li Wenbo , Wang Xinyue , Lu Hailong , Yan Jun 
Published: August 2024

Abstract
The carcass layer is the innermost structure of marine non-bonded flexible risers, primarily responsible for withstanding external hydrostatic pressure to prevent the risers from collapsing and failing. The carcass layer is formed by repeatedly bending metal strips through multiple rolling processes. This unique processing method results in significant non-uniform residual stresses within the carcass layer. The impact of these residual stresses on the mechanical performance of the carcass layer is currently not well understood. Therefore, determining the magnitude and distribution of residual stresses within the carcass layer is of great importance for the design and analysis of flexible risers. To address the issue of traditional measurement methods being unable to measure residual stresses within the unique structure of the carcass layer, this study employed X-ray diffraction techniques with a discrete stress analyzer. The axial and circumferential distribution of residual stresses for three different sizes of carcass layers were measured. The experimental results indicate that the axial residual stresses in the carcass layer are predominantly tensile stresses. The circumferential residual stresses are uniformly distributed along the circumferential direction, with the maximum circumferential residual tensile stress located at the outer bend and the maximum circumferential residual compressive stress located at the inner bend radius.