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Recent events in offshore oil and gas markets show the need for elaborate treatments of uncertainty throughout the design process and lifecycle management of maritime engineering systems. Offshore construction vessels are subject to uncertainty stemming from both economic factors modelled as stochastic processes, and from discrete factors like regulations and contract requirements. We present a simulation framework for valuation of flexible offshore construction vessels incorporating real options analysis and epoch-era analysis. Based on compliance with a set of contracts and the potential revenue to be earned from these contracts, the model maximizes expected net present value for each contract period. Benchmarking a flexible design of an offshore construction vessel against an inflexible design, we estimate the value of flexibility and find strategies for managing the design through the lifecycle. The results show that significant gains in the value of the vessel result when design changes are taken into account. This is an Accepted Manuscript of an article published by Taylor & Francis in [Ship Technology Research] on [01 Jun 2017], available at http://www.tandfonline.com/doi/full/10.1080/09377255.2017.1334311

The hazard identification is one of the most significant issues of the safety management process. Conventional approaches to hazard identification in a job safety analysis (JSA) tend to failure of identifying all the potential hazards involved in a work and can lead to accidents. How to identify the hazards thoroughly has becoming a challenge. The energy source based job safety analysis (ESBJSA) method proposed in this paper, aimed to identify and assess all the potential hazards effectively by applying an analysis basis on energy sources. Through clarifying the energy sources in each sub step and identifying the corresponding potential hazards of each energy source respectively, the measures and solutions to eliminate or reduce the risks can be determined. The ESBJSA method was applied in an offshore construction and installation project, and the total recordable incident rate (TRIR) result was reduced 50% when compared with another similar project using conventional JSA method. Additionally, ESBJSA is a technique that can be fully applicable to many high risk construction and installation projects in shipyard.

This chapter presents an overview of oil and gas investment and different types of offshore structures, from shallow water to deep water, and other structure configurations such as floating, production, storage, and offloading and tension-leg platforms. The offshore project phase, focusing on control of the engineering from appraisal, selection, definition, and execution, is discussed in this chapter. The offshore project investment and the cost estimate corresponding to each phase of the project are also discussed. To understand the oil and gas business, the first step is to define the offshore project target and objective, and then how to provide a project which is technically matched throughout all phases with the business requirements.

The relationship between digitalization, digital innovation, and digital transformation is an emerging topic in information systems (IS) research. Whereas IS researchers widely acknowledge that digitalization underpins both digital innovation and digital transformation, just how and by what mechanisms link digital innovation with digital transformation remains underexplored. Differentiating between ‘digital infrastructure innovation’ and ‘innovation in digital infrastructure’, this paper contributes towards current discussions by empirically elaborating how the open-ended and generative potential of digital innovation in practice has to be negotiated against the installed base of technical and organizational arrangements in digital transformation. We pursue this argument through a case study of digital innovation coordination in an inter-organizational digital innovation project with the goal of instigating digital transformation within the offshore construction industry.

Summary Objects within marine sediments pose a serious risk for offshore construction projects. Their detection is difficult with conventional geophysical methods. We present here a new data acquisition and processing strategy to detect and localize boulders through dedicated diffraction imaging. The new Manta Ray data acquisition system allows the recording of seismic data that is suitable for specialized diffraction imaging at depth. Seismic data processing using beamforming and synthetic aperture allows a high-resolution localization of diffractors in the sub-seafloor. The results may be used for the efficient de-risking of offshore construction sites with regards to glacial boulder locations.

The article tells about the risks of low-culture construction of oil facilities on the Arctic shelf. The long-term, practically neglected exploitation of the unique natural resources of the Russian North and the low culture of their development led in a number of its regions, including the waters of the Arctic seas with islands, to an emergency ecological situation - the partial and sometimes complete destruction of the fragile Arctic natural habitat of the small peoples of the North and the created cities and villages. Without proper environmental support, economic activities continue in the field of extraction, transportation and processing of natural resources. The progressive pollution of rivers and lakes leads to a qualitative depletion of water resources - a change in the composition of the waters of the Arctic Ocean. The danger of oil pollution of the marine environment is associated with plans for its production on the continental shelf of the Russian Federation. The oil and gas production complex in the Russian Arctic regions are being formed on the basis of already discovered fields and will develop as other promising fields are developed.

Pan Malaysia Maintenance, Construction and Modification (PM-MCM) Contract 2018 – 2023 is a PETRONAS-led initiative in collaboration with Malaysian Oil & Gas Operators, which are also known as Petroleum Arrangement Contractors (PAC), aimed at cost optimization through the technical standardization of offshore Hook-up and Commissioning (HUC) and Topsides Major Maintenance (TMM) works. The initiative was participated by ten (10) Petroleum Arrangement Contractors (PACs) operating in Malaysia (redundant). The initiative competitiveness relied heavily on the number participating PACs in order to accumulate and integrate sufficient volume of work through sharing of their long-term offshore work plan over a period of 5 years with active contribution on lessons learned, best practices, and challenges. Leveraging on high volume of work per region will generate the economics of scale thus drive cost reduction. The technical standardization is achieved through the identification of minimum requirements for each work (HUC and TMM) by operators, and where applicable, common specifications are accordingly derived. This simplifies the requirements and accordingly reduces the number of specifications to be complied across the region, thus, effectively allows the HUC/TMM Contractors to competitively quote the best price for the services. Apart from the technical standardization and optimization above, the initiative is further supplemented through the standardization of the Contract Terms and Conditions among the PACs. However, landing to an agreement amongst the ten (10) established Oil & Gas Companies was crucial and considered as a major challenge, as each company had operated differently under their own set of Terms & Conditions. Despite this, consensus achieved towards standardization. In assisting the tender evaluation and aligning with PETRONAS’ effort towards Digitalization of its Busines Operation, digital tools were deployed. Online eAuction and digital bid price analyzer were extensively used to commercially evaluate and to identify best value for PETRONAS and PACs, respectively. In conclusion, the PM-MCM contract was successfully awarded with a significant cost reduction against the original estimated cost by approximately 40%. In comparison to previous contracts, Pan Malaysia MCM also recorded significant reduction in most of the unit rates of similar services rendered. Market feedbacks obtained by participating bidderss indicated that the standardization had indeed helped the participants to lower their prices. Pan Malaysia Maintenance, Construction and Modification Contract has brought forward industry players into one crucial objective of cost optimization. The collaboration between PETRONAS and PAC which resulting for greater impact and value to all players involved through productivity improvement and cost reduction.

Nowadays, since, subsea equipment becoming larger and heavier, risks of the lifting/lowering operations by offshore support vessel (OSV) are also increasing and thereby predicting coupling motions of the vessel and whirling equipment and hydrodynamic forces acting on the suspended load in splash zone are important to prevent clash accidents and damage on lifted subsea equipment etc. Model experiment using OSV with heavy suspended load was conducted in Deepsea Basin in National Maritime Research Institute (NMRI). The experiments were carried out with several regular and irregular waves and heading angles. The OSV was moored with 4 lined spring system. During the experiments, the motions of moored OSV and suspended load were measured with visual 3D motion capture system. Computation fluid dynamics (CFD) simulations were conducted using CFD Solver NAGISA which was developed in NMRI to investigate the dynamics and hydrodynamical aspects. Dynamic overset grid method and multibody dynamics model were applied to reproduce the coupling motions of the vessel and suspended load. The CFD simulations were carried out when the suspended load is in the splash zone to predict hydrodynamic forces acting on the lifted equipment. The CFD simulation results were validated with the model experiment comparing with motions of OSV and suspended load.

One of the advantages of floating offshore wind turbines (FOWTs) is that they can be designed to be easily wet towed and installed to reduce the cost of offshore construction. In this paper, a fully coupled towing system numerical model is established for a novel 10 MW FOWT concept, namely, a submerged floating offshore wind turbine (SFOWT) to investigate the towing performance. Firstly, the numerical simulation is validated by comparison with model experiment results. Then, a series of numerical simulations are conducted to predict and compare the towing performance for a three-column SFOWT (TC-SFOWT) and a four-column SFOWT (FC-SFOWT) under different wave conditions. The results show that the two forms of SFOWT have good towing performance when the significant wave height is less than 5 m, which is the maximum wave height for the allowable towing condition. The FC-SFOWT shows relatively better performance in heave motion and roll motion, but the towing force is relatively larger compared with the TC-SFOWT under the same condition. When the significant wave height is 5 m, the maximum values of heave motion, pitch motion, and roll motion of the TC-SFOWT are 2.51 m, 2.14°, and 1.38°, respectively, while they are 2.25 m, 2.70°, and 1.21°, respectively, for the FC-SFOWT. Both the roll motion and the pitch motion are satisfied with the requirement that the roll and pitch are less than 5° during the towing process. The mean towing force of FC-SFOWT is 159.1 t at the significant wave height of 5 m, which is 52.8% larger than that of TC-SFOWT. The peak period mainly influences the frequency where the response peak appears in power spectra. The findings in this paper could provide some guidelines for wet towed operations.

The significant lead times and costs associated with materials and equipment in combination with intrinsic and weather related variability render the planning of offshore construction projects highly complex. Moreover, the way in which scarce resources are managed has a profound impact on both the cost and the completion date of a project. Hence, schedule quality is of paramount importance to the profitability of the project. A prerequisite to the creation of good schedules is the accuracy of the procedure used to estimate the project outcome when a given schedule is used. Because of the systematic influence of weather conditions, traditional Monte Carlo simulations fail to produce a reliable estimate of the project outcomes. Hence, the first objective of this research is to improve the accuracy of the project simulation by creating a procedure which includes both uncertainty related to the activities and an integrated model of the weather conditions. The weather component has been designed to create realistically correlated wind- and weather conditions for operationally relevant time intervals. The second objective of this research is to optimise the project planning itself by using both general meta-heuristic optimisation approaches and dedicated heuristics which have been specifically designed for the problem at hand. The performance of these heuristics is judged by the expected net present value of the project. The approach presented in this paper is tested on real data from the construction of an offshore wind farm off the Belgian coast and weather data gathered by the Flanders Marine Institute using measuring poles in the North Sea.

Despite the fact that offshore wind energy will tend towards the floating technologies their economic impact has not been practically evaluated yet. In this context, the aim of this article is to characterize the possible economic alternatives which can be considered in the life-cycle of floating offshore wind farms based on their life-cycle costs. Several groups of variables have been considered for determining these alternatives: wind turbines, floating platforms, mooring system, anchoring process, kind of seabed, electric system, installation, shipyard and maintenance. The method proposed has been applied to the case of the North-West coast of Spain (Galicia region). For this case test three different platforms have been analyzed: Tensioned Leg, Spar and Semisubmersible platforms. Results, which are presented by using maps of the area, conclude that offshore substation, string electric configuration and “tree fall” decommissioning method are the best options for minimizing the costs. In addition, the installation method will be conditioned by the type of floating platform and mooring material, whereas the disposition and anchor decisions are dependent on the geographic location. Results show how the methodology proposed is useful to characterize economically the life-cycle of a floating offshore wind farm.

The prediction of underwater noise emissions from impact pile driving during near-shore and offshore construction activities and its potential effect on the marine environment has been a major field of research for several years. A number of different modeling approaches have been suggested recently to predict the radiated sound pressure at different distances and depths from a driven pile. As there are no closed-form analytical solutions for this complex class of problems and for a lack of publicly available measurement data, the need for a benchmark case arises to compare the different approaches. Such a benchmark case was set up by the Institute of Modelling and Computation, Hamburg University of Technology (Hamburg, Germany) and the Organisation for Applied Scientific Research (TNO, The Hague, The Netherlands). Research groups from all over the world, who are involved in modeling sound emissions from offshore pile driving, were invited to contribute to the first so-called COMPILE (a portmanteau combining computation, comparison, and pile) workshop in Hamburg in June 2014. In this paper, the benchmark case is presented, alongside an overview of the seven models and the associated results contributed by the research groups from six different countries. The modeling results from the workshop are discussed, exhibiting a remarkable consistency in the provided levels out to several tens of kilometers. Additionally, possible future benchmark case extensions are proposed.

The offshore pipeline network in the U.S. Gulf of Mexico is the largest and most transparent system in the world. A review of deepwater projects in the region provides insight into construction cost and installation methods and the evolution of contract strategies. Pipeline projects are identified as export systems, infield flowline systems, and combined export and infield systems, and three dozen deepwater pipeline installations from 1980–2014 are described based on OTC/SPE industry publications and press release data. Export lines and infield flowlines are equally represented and many projects used a combination of J-lay, S-lay and reel methods with rigid steel, flexible line, and pipe-in-pipe systems. The average 2014 inflation-adjusted cost for pipeline projects based on OTC/SPE publications was $2.76 million/mi and ranged from $520 000/mi to $12.94 million/mi. High cost pipelines tend to be short segments or specialized pipeline. Excluding the two cost endpoints, the majority of projects ranged from $1 to $6 million/mi. The average inflation-adjusted cost to install deepwater pipelines in the U.S. Gulf of Mexico based on available public data is estimated at $3.1 million/mi.

Forecasting of wave conditions plays an essential role for offshore construction and maintenance. Recently, machine learning-based wave forecasting models have been developed and their integrated usage with physics-based numerical models has become popular. These studies mostly apply Feed Forward Neural Networks (FFNNs) with an emphasis on prediction of time-series of waves, tides and storm surges. As a particularly different approach, we develop a deep learning-based wave forecasting model using Long Short-Term Memory (LSTM) network under Recurrent Neural Networks. As a case study, the model will be utilized to predict the wave conditions (low or high) near the Tottori Port, Japan.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/oMvIS9zkIOs

Structural lightweight concrete has various applications including the construction of multi-story buildings, bridges, offshore oil platforms and other reinforced concrete structural elements. Structural lightweight concrete also was used in offshore construction. The development of compositions of high-strength lightweight concrete with an average density of 1100-1500 kg/m3 may be in demand for the manufacture of most of the typical concrete products with an ordinary strength 20-35 MPa. This study have shown that granular expanded siliceous aggregates can be used as an alternative to hollow microspheres to obtain high mechanical characteristics of lightweight concrete. Based on the principles of producing high-strength lightweight concrete using the example of “Thermogran” granules the possibility of achieving strength of lightweight concrete of more than 45 MPa with an average density of less than 1600 kg/m3 is shown. In the same time, specific consumption of cement on 1 MPa of concrete strength is 8.1…8.8 kg/MPa.

With the growing demand of large-scale heavy lift vessels in the deep-sea offshore construction works, high performance of Dynamic positioning (DP) systems is becoming ever crucial. However, current DP systems on board of heavy lift vessels do not consider model uncertainty (typically arising from mooring forces). In this paper, an observer-based robust controller is designed that can tackle model uncertainty in hydrodynamic damping and mooring forces, environmental disturbances as well as can filter out the high-frequency vessel movement. Closed-loop system stability is analytically established in terms of uniformly ultimately boundedness. In addition, several key performance indicators are provided for tuning the performance of the controller. The effectiveness of the proposed control framework is studied in simulation with a crane-vessel system.

The radiated acoustic waves from impact pile driving produce high noise level into the water which may cause damage to marine mammals living close to the offshore construction location. In this paper, a linear, axisymmetric finite element (FE) model is applied to predict pile driving noise in the water. Measurement from bottom-mounted hydrophone deployed at a site 230 m from the source is used to validate the model results. The comparisons between model results and measurement, such as structure modal analysis, sound exposure level at different pile penetration and unweighted one-third octave band level, are presented and show useful predictions of noise level from the model. Furthermore, a time domain case is demonstrated to show Mach wave associated with the radial deformation of the pile and supersonic speed. Finally, analysis of variance (ANOVA) and linear regression are made after verifying the model prediction. The ANOVA results identifies some significant parameters on pile driving noise and the empirical equation from linear regression represents the noise level from pile driving impact at close range. These are possible metrics on offshore wind farm environment assessment in Taiwan.

Lifting operation though the wave splash zone is challenging. Careful numerical analysis in the design phase is needed to minimize associated risks. This study addresses numerical modeling and analysis of the splash zone lowering of a large subsea spool. A typical offshore construction vessel is used for the operation. The objective is to compare the effects from different numerical methods and parameters on the allowable sea states and the operability. These methods and parameters include wave short-crestedness, shielding effects from the vessel, wave direction and wave seed number. A coupled numerical model of the spool-vessel system is established in SIMO program, which is a simulation tool for marine operations. Slamming and submergence-dependent loads on the spool during the transient lowering process are calculated. A large number of time-domain simulations has been performed to derive the allowable sea states. The operational criteria for assessment of the sea states include slack sling, snap loads in wires and clearance between spool and the vessel. Operability analysis of the operation at one reference site in the Barent Sea is established using 50-year hindcast data. The influences from different methods on the allowable sea states and the operability are compared and discussed in detail.

In the European Waters there is still a huge amount of Unexploded Ordnance (UXO) in place. Different causation scenarios from war hostilities and military actions have led to an unknown amount of different UXO in the Baltic Sea, as well as in the North Sea. Sediment movement, currents or missing information make it difficult to determine the exact position or the amount of remaining UXO with geophysical methods. Since the upcoming and growing economic use of the Baltic Sea (windfarms, pipelines, cables), an extensive Risk Mitigation and the development of working procedures are becoming more and more inevitable. There are well established procedures to perform a historical investigation for hazard identification on land. This stepwise procedure is defined in a German working guide on explosive ordnance clearance. It is transferred to be used in German waters and can also be used for other countries around the Baltic Sea. The historical investigation prepares a geophysical investigation previously to offshore construction work and will reduce the costs and minimize the risk for personnel, equipment and the environment.

The analysis of root causes of the latest Major Accidents in the Oil&Gas industry has shown that there is little correlation between having and religiously following an effective Occupational Health & Safety Management System and the assurance of Asset Integrity. While Asset Integrity may be considered as a well-established framework in offshore drilling and production operations, this is not yet the case for typical offshore construction operations. Saipem has developed an Asset Integrity Management Model, based on internationally recognized standards, aimed at controlling the risks related to Major Accident Hazards posed by the offshore operations in the company portfolio, including offshore construction. The model identifies the Safety Case as the key process to analyse Major Accident Scenarios. The Safety Case identifies barriers in place to prevent escalation to major events and, when failing to prevent, at least to mitigate final consequences. Barriers entail a mix of three main types of Safety Critical Elements: Equipment, Competences and Procedures. While the identification and assurance of Performance Standards of (Safety Critical) Equipment is systematic and supported by a consolidated approach, the same cannot always be said for Safety Critical Competences and Safety Critical Procedures, due to their "soft" nature. As for Equipment, where key parameters outline the expected performance (e.g. functionality, reliability/availability, vulnerability), for Safety Critical Competences and Safety Critical Procedures an equivalent set shall be established. Another major challenge is posed by setting meaningful and effective KPIs to monitor all key elements that contribute to building Asset Integrity. Examples are Performance Standards of Safety Critical Elements, Management of Change, Procurement & Design of Equipment, Document Management, Communication & Awareness. Asset Integrity lagging and leading indicators are available in the literature, especially for Process Safety, but in the field of offshore construction, this is not the case. Saipem is pioneering the implementation of an Asset Integrity approach onboard Offshore Construction Vessels, addressing in particular non-marine Safety Critical Equipment, Competences and Procedures.

This study is aimed to develop the dynamic analysis technique for a floating aquaculture in a shallow water region under the harsh sea condition. In case of the installation region to transform from a coastal area to the offshore area, the influence of sea bed with sea waves on the mooring lines was announced to be significant by other authors. In this study, the numerical tool was developed to solve dynamic behavior of the floating barge coupled with mooring lines in a shallow zone of the sea considering the influence of sea bed on the floating system.Copyright © 2016 by ASME

The construction of Core-Loc armour layers requires that unit centroids are systematically placed according to a grid pattern. To give the type of interlock required by this unit’s developers, neither a fully random nor a strict identically orientated neighbour-to-neighbour pattern of placement is successful. This means that a certain degree of irregularity in unit orientations is required. To guide the contractors, armour layers deemed to have been placed with acceptable standards, units must satisfy special placement criteria given by the Core-Loc developer. There is a lack of instruction on how to achieve such ‘acceptable irregular orientations and placements’. The construction success seems more a function of experience and skill of the crane operator than any repeatable or potentially machine-programmable methodology. For this reason, it is also challenging to design a repeatable numerical method that reliably positions units into armour layers that satisfy the developer’s special placement criteria. For the numerical creation of full-scale Core-Loc armour layers, a placement method was briefly introduced in previous work by the authors, based on the multi-body FEMDEM code, Y3D-R combined with a versatile deposition code, POSITIT. While satisfactory layers were previously demonstrated, here we elaborate on the sensitivity of the placed armour layer attributes to the numerical construction process parameters. In this work, new capabilities of POSITIT/Y3D-R are harnessed in a computationally efficient row-by-row numerical placement of units. These include vibration and artificially low friction in order to achieve acceptable irregular packs of the appropriate packing density. To examine the role that initial armour layer build quality has on unit immovability or the percentage of units that do not displace significantly under a standard oscillatory disturbing force, a sinusoidal velocity vibration is applied to the foundations in a series of tests on differently constructed full-scale armour layers. What emerges from this sensitivity study is an implicit verification of the importance of the technical requirements set by the developer of Core-Loc units.

In the early stages of oil and gas exploitation, it is important to rapidly identify which production platform is likely to deliver its utmost value. This study first explores the key features and constraints of the most commonly used fixed and floating offshore platforms then proceed to discuss the current available production technology. Platform selections are based on several factors such as stability, water depth and environmental conditions. Drilling can be done from the platform or another mobile unit. As most new offshore operations turn to semi-submersible platform and drill rigs, it is perceived as the most promising platform by oil and gas industry.

Remotely Operated underwater Vehicles (ROVs) play an important role in a number of operations conducted in shallow and deep water (e.g.: exploration, survey, intervention, etc.), in several application fields like marine science, offshore construction, and underwater archeology. ROVs are usually equipped with different imaging devices, both optical and acoustic. Optical sensors are able to generate better images in close range and clear water conditions, while acoustic systems are usually employed in long range acquisitions and do not suffer from the presence of turbidity, a well-known cause of coarser resolution and harder data extraction. In this work we describe the preliminary steps in the development of an opto-acoustic camera able to provide an on-line 3D reconstruction of the acquired scene. Taking full advantage of the benefits arising from the opto-acoustic data fusion techniques, the system was conceived as a support tool for ROV operators during the navigation in turbid waters, or in operations conducted by means of mechanical manipulators. The paper presents an overview of the device, an ad-hoc methodology for the extrinsic calibration of the system and a custom software developed to control the opto-acoustic camera and supply the operator with visual information.

The present paper contains statistical analysis of modelled sea state data for the Western Baltic Sea for a time period of 52 years. Twenty charts were created, showing mean wave heights and frequencies of occurrence for different seasons. Taking a closer look at three potential areas for offshore wind energy in the Western Baltic the following mean significant wave heights were calculated (from west to east): Fehmarnbelt 0.6 m, Kadet Furrow 0.7 m and Arkona Basin 0.9 m. A comparison with waverider buoy measurements at five locations for different time series proves the good quality of the modelled data. These charts impart detailed information on the sea state from a spatial and temporal perspective which can be utilized by a wide range of users from different backgrounds. An exemplary monthly analysis of one location shows the possible application of the data set.

The offshore construction environment can be very difficult to be accurately predicted, due to various uncertainties in the geotechnical elements, and highly probabilistic events at which ocean conditions govern the design. The integrity assessment and life extension activities towards end of field life is becoming very common in older fields surrounding Malaysia, and other areas such as the Arabian Gulf and the North Sea. The in-line measurement of the existing residual stresses on these assets is very critical for the remaining life assessments, and also to categorise assets for shutdown to undergo rehabilitation work. The novel idea of using ultrasonic waves is developed and explained in detail in this paper. This method is based on the measurement of the time of propagation of the critically refracted longitudinal wave components travelling along the subsurface region of the specimen. Numerical validation is backed up by experimental work to verify this method to be fit-for-purpose for the intended application, through the development of an acoustoelastic calibration curve for several sectional shape/sizes of carbon steel material. These tests show good correlation between the numerical and experimental work, and this has the potential to be a reliable tool for use in the offshore/marine engineering sector where shutdowns are expensive.

Summary Offshore construction and exploration require preliminary characterisation of the near-subsurface, which includes evaluation of potential geological hazards. In this study, we present the novel data on the geohazards on the shelf of the Kara Sea. Integrated interpretation of the 2D high-resolution (HR) and 3D exploration reflection seismic data allowed us to evaluate geohazards at different scales from the sea bottom to nearly 1 km depth. Potential geohazards on the shelf of the Kara Sea include paleovalleys, gas-bearing sediments, accumulations of permafrost, intervals with severe faulting and tectonically weakened zones possibly associated with the upward migration of fluids.

Heavy lift crane vessels play an important role in offshore installations. Previous studies have shown that position control systems for these vessels can cause unstable positioning behavior during offshore construction assignments under specific conditions, e.g., change of environmental loads. Some control methods, such as crane force feedforward to the controller or the estimator, have been developed to improve the stability of the position control systems. However, these methods depend on the accurate estimation of the crane force and fast reaction of thrusters, which are difficult to obtain under working conditions. To make the positioning system stable, and compensate the controller for the changing crane stiffness and the systems onboard, two methods will be provided. One is to increase the flexibility of the system, while the other one is to increase the robustness. Two control methods, adaptive PID and H-infinity, are adopted and the results are compared. During simulations, the two controllers can dispose of crane modeling error and time delay of thrusters. Adaptive PID has a smaller variance under higher wind and wave load, while H-infinity controller has a larger clearance with the platform.

Structural cables are widely adopted around the world in offshore construction, sports stadia, large scale bridges, Ferris wheels and suspended canopy and fabric structures. However, the robustness of such structures to blast or impact is uncertain with a particular concern related to the loss of a primary structural cable when damaged by high velocity blast fragmentation. This paper presents the first ever numerical and experimental study on commonly used high-strength steel spiral strand cables subjected to high velocity fragment impact. Spiral strand cables were impacted by 20 mm fragment simulating projectiles travelling at velocities between 200 and 1400 m/s. Complex 3D non-linear finite element models were developed and carefully compared with experimental tests. The penetration resistance of the cables and resultant damage were studied with respect to fragment impact velocity. It was found that for all the impact velocities, the fragment penetration depth was less than half of the cable diameter demonstrating a considerable amount of resilience. Considering the damage caused, the residual cable breaking strengths were estimated and found to be still higher than the minimum breaking load of an un-damaged cable. The numerical models were also able to reproduce the main features of the impact tests, including the extent of localised damage area, the fragment penetration depth and mode of individual wire failures, thus demonstrating their potential to be widely used in industry for structural resilience and robustness assessments by structural engineers.

Recent changes in the global construction industry coupled with rising challenges as a result of the dynamic nature of offshore operations have greatly underscored the need for stakeholders to evolve safety management systems that optimize safety during the execution of their construction project operations. As a result, the offshore industry has witnessed significant changes which currently place a greater premium on effective safety management, with organizations’ requiring to look across the whole project's life cycle. To optimize safety during operations, formulating effective safety management systems becomes a crucial challenge faced by industry stakeholders. Utilising evidence from semi- structured interviews, this paper examines senior managers’ role in safety leadership in Nigerian offshore oil and gas projects. It concluded that leadership style is critical for the implementation of any effective safety management system utilised during offshore construction projects. The findings also facilitate an in-depth understanding of lessons learnt from offshore construction projects and will be useful for improving the overall safety management strategy of organisations in line with important factors usually considered by the global offshore oil and gas industry.

Master's thesis in Offshore structural engineering In the last few years, the car industry has developed hybrid battery systems with lower battery price, higher capacity and improved safety. These improvements in performance have led to an increased interest to utilize the technology in marine applications. To satisfy the requirements of redundancy in critical situations vessels are required to run multiple engines at low to medium loads during most of operations in station keeping. Traditional combustion engines are designed to have the optimal level of fuel consumption and lowest emission per kilowatt hour when operating at medium to high loads. This practice therefore represents an overall loss and is unfavorable for environment and fuel consumption. This thesis investigates the effect and viability of applying a Hybrid Battery System (HBS) on a Platform Support Vessel (PSV) by using the battery to optimize the original power system. For the case study, the vessel Viking Energy has been considered. Viking Energy is the first vessel with a HBS approved as a redundant power source in critical operations. The system allows the vessel to reduce the numbers of active engines while ensuring instant available power if required. The remaining active engines are then operating closer to the optimal level, ensuring lower emission and fuel consumption per kilowatt hour. This study analyzes and quantifies the effect in fuel consumption and cost after implementing the HBS to the PSV. It also analyzes the weathers influence of the fuel consumption for the vessel with and without HBS. The study is based on a six-month sample period where the HBS was fully operative. The analysis gave an annual reduction in fuel of 13% comparing the sampling period with historical data given the same time distribution for the vessel. Normalizing both to actual distribution over a three-year operation period gives a calculated reduction of 17% due to more favorable distribution. The difference is mainly due to higher portion of Dynamic Positioning (DP) mode in the historical data. The economical evaluation concluded that the minimum threshold for overall fuel reduction to be 15% for the investment to break even in a ten-year perspective. A vessel is recommended to operate 34% or more of the time in DP or a mode providing similar level of fuel saving to meet an overall reduction of 15%.

Introduction The Offshore Environment Offshore Site Investigation Soil Behaviour Piled Foundations Shallow Foundations Anchoring Systems Mobile Drilling Rigs Pipeline and Riser Geotechnics Geohazards

With the constant increase of known oil reserves in deep and ultra-deep waters, floating production systems (FPS) have been established as the main option for offshore production activities. This work presents recent advances regarding an innovative application of evolutionary optimization methods to the design of mooring systems for FPS. Here the focus in in the consideration of actual scenarios with seabed obstacles and other restricted areas where anchors cannot be positioned. The optimization tool employs the Particle Swarm Optimization (PSO) method. The constraints are treated by specialized constraint-handling techniques, and each candidate solution is evaluated through nonlinear analyses coupling the hydrodynamic model of the platform hull with a Finite Element model of the mooring lines and risers. A case study illustrates the application of the optimization for a real-world scenario.

There is significant evidence that the low-frequency mean acoustic noise pressure level in the ocean has been constantly increasing in the last decades. The main noise sources responsible for this increase were identified as ship traffic, offshore construction and oil & gas surveying. The Portuguese Navy funded SUBECO project aims at deploying a network of multiparametric offshore buoys for environmental and acoustic monitoring. A preferred location for the individual buoys is within or close by the ship traffic separation lanes along the west coast of Portugal. It is therefore expected that the received acoustic field will be dominated by shipping noise as a mixture of both short and long range ships. Most ships will have an AIS so their position may be known at all times. One of the objectives of this network is to use the recorded sound to infer and calibrate model predicted noise in a wider area. This work proposes a relatively simple technique for estimating the radiated noise level of ship tracks within acoustic reach of a single (or a small number of closely localized) hydrophone(s). It is expected that the data constrained predicted field with the estimated source levels will provide a better fit to the actual wide area acoustic field. This work is a contribution to fulfill the requirements of Portugal to the European Union Marine Strategy Framework Directive (MSFD) aiming at a good environmental status.

The paper is in support of the effort by the Marine Renewable Energy (MRE) Committee of the ASCE Coasts, Oceans, Ports, and Rivers Institute (COPRI) for setting up a guide document for offshore renewable energy foundations. The guide would use standard design codes for fixed foundations and mooring anchors in API, ISO and DNV. This paper focuses on specific aspects of design of offshore wind turbines that distinguish them from oil and gas installations. Emphasis is placed on the source of loading and the corresponding response of soil resistance. The paper also how soil investigation for offshore windfarms differ from oil and gas and economic procedures for carrying out such investigation. Foundation design of offshore structures requires identifying the critical loads. In the case of oil and gas foundations, the source of the load is the wind or wave or a combination of both. For offshore wind towers on fixed foundations, an additional source of dynamic load is the turbine blade rotation during operation. The frequencies of the rotor revolution and that of the blade passing the tower, need to be checked in relation to the resonance frequency of the foundation. The foundation dynamic response therefore depends largely on the stiffness and dampening characteristics. Most offshore wind turbines tend to be located in relatively shallow water depth where difficult multi-layered soils tend to be dominate. This paper also discussion installation suction buckets of fixed foundation in difficult multi-layered soils.

The Stones project is located in the Walker Ridge (WR) area approximately 200 miles due South of New Orleans in ~9500 feet of water. The host facility is a Floating Production Storage and Offloading (FPSO) vessel with a disconnectable moored turret buoy (BTM) that allows the FPSO to move off site in a hurricane event. Each of the nine moorings are made up of a suction pile – chain – polyester – chain – spring buoy – top chain assembly. These connect to the circumference of the BTM at the keel. The subsea infrastructure, including 2 flow-lines, one gas export pipeline, and two umbilicals, are supported by the BTM. The pipelines and all umbilical fluids, electrics, and fiber are connected or disconnected from the FPSO via dry internal turret connection systems. This paper provides an overview of the transportation and installation of the moorings, turret buoy. Key challenges include water depth world record for FPSO moorings, transportation and handling of the world's largest disconnectable buoy, and project execution during an extreme eddy current event.

The dynamic loads experienced when deploying structures with large suction anchors from an offshore construction vessel has been studied. Both model tests and CFD-analyses have been used to calibrate a numerical model of a typical Integrated Template Structure (ITS). The numerical model has then been used in time domain analyses in order to study the dynamic loads in the main lift wire when the ITS is lowered through the splash zone. An overall conclusion from this study is that from a lifting point of view neither the structural integrity of the ITS nor the crane will be jeopardized when crossing the splash zone in a typical deployment operation on the Norwegian Continental Shelf (NCS). The CFD analyses reveal the importance of entrapped air and water when the top of the suction anchor is crossing the splash zone. For the Gjoa ITS suction anchors used in the study, the openings on top of the suction anchors are quite large (perforation of 6%) which limits the amount of entrapped air during the water entry phase and also the amount of entrapped water in the water exit phase.

In order to acquire mechanical performance of High cap supporting frame-shear structure, in view of the sea high cap supporting frame-shear theory analysis and numerical simulation of structure is less, this paper performs numerical simulation analysis for pile caps-soil-the upper structure using the finite element software ANSYS. Expression equation of wave force is given, and three-dimensional finite element model is established. By Analysis the deformation and stress of pile foundation and pile caps under different load combinations are obtained, and the deformation, bending moment of pile top, axial force are checked, finally the feasibility of the system is verified, and these can provide a reliable basis and reference for reasonable design of offshore structures. High cap supporting frame-shear structure for its strong adaptability is widely used in offshore construction system.

This study investigates the effects of the compressive strength and area ratio of coarse aggregate of concrete for offshore construction on the erosion depth. To evaluate the erosion resistance of concrete, test was performed according to ASTM C 1138 using a plain mix with design strength of 30 MPa using only Portland cement and five other mixes including different quantities of fly ash and blast furnace slag. The test results showed that the erosion depth is influenced not only by the compressive strength but also by the area ratio of coarse aggregate.

Recently, a number of wind turbines are being installed due to the increase of the interest in green energy. Such wind turbines are installed on land or offshore, and most of them are being installed on land because of easy installation. However, because it is possible to get better wind quality in offshore, the request for an offshore wind turbine is increasing and some heavy industries including shipyards are producing different sizes of offshore wind turbines. A floating crane is used for constructing the offshore wind turbine because its weight amounts to several hundred tons. Thus, it is very important to secure the safety during the construction. In this study, a dynamic response simulation of the offshore wind turbine suspended by the floating crane is performed. For this, we supposed that the motion of the floating crane and the wind turbine has 14 degrees of freedom, and there is the interaction by constraints among them. In addition, hydrostatic and hydrodynamic forces which are independent of e...

Offshore plants is an intensive industry where real value is able to be created when EPCIC(Engineering, Procurement, Construction, Installation, Commissioning) is combined. Many universities and educational institutions have established major fields and graduate schools related in offshore construction and engineering as well as safety training and occupational courses. Most of the personnel who have graduated and passed those educational institutions have been working in domestic shipbuilding companies and marine equipment manufacturers. Therefore, customized education and training should be developed according to the educational demands required and then skilled personnel are needed to be supplied at proper times. This study, therefore, has found personnel demands inside and outside the country and occupational sections of offshore plants. Consequently, this study suggests making up a council comprised of shipbuilding companies, marine equipment manufacturers and educational institutions with government organization, and also researches the necessity of getting a job of personnel trained by the customized education. These results are expected to contribute to the development of education curriculum of domestic offshore plant as well as ODC(Offshore Development Center).

Offshore industry has been welcoming to composite material for its saliences. Features such as corrosion and temperature resistance, construction cost reduction, and superb fatigue performance are some of the reasons for this choice. Steel tube-encased composite is an appropriate found composite replacement for traditional offshore construction. Regardless of all its advantages, they suffer from the interfacing problem between composite and steel layers; however, magnetostrictive nanofillers are proposed to increase the integration between the layers. Therefore, current effort is discussed the vibrational behavior of the proposed robust steel tube column as well as the actuation characteristics of the magnetostrictive nanofillers in encased composite. The result reveals that, the steel tube-encased composite columns exhibit greater stiffness in compare with traditional steel tube. Furthermore, magnetostrictive nanofillers have shown higher actuation capability of vibration at seismic mode.

To increase the lifting capacity and minimize the cost and time for building a ship and offshore structure, block lifting with multi-cranes becomes more and more important. In this paper, therefore, dynamic response analysis of the multi-cranes is performed for block lifting operation. By this simulation, one can confirm the dynamic effects, such as dynamic motion and load, to prevent fatal accidents during the multi-crane operation. There are several types of crane and the crane systems consist of several rigid bodies. These rigid bodies are connected with various types of joints and wire rope, and the crane system is called as multibody system. To carry out the dynamic simulation of the crane system, therefore, the program for dynamic analysis of multibody system is developed. Among the several types of the cranes, the floating crane is operated on the sea water. Therefore, the developed program includes the function for calculating the hydrostatic and hydrodynamic forces. Using the dynamics simulation program developed in this paper, a dynamic response simulation of several cases of block lifting with multi-cranes are carried out, and the simulation results are validated by comparing them with the measured data from the shipyard.

Handling Increased Tensions in Deeper Water Depths With ultradeep installations reaching deeper than 2000 m, laying pipe on the seafloor can present challenges, such as increased holding tensions on the pipe during installation. Proper tension must be maintained to prevent the buckling that can be caused by the hydrostatic pressures acting on the pipe.

Friction stir welding (FSW) offers both economic and technical advantages over conventional fusion welding practices for welding line-pipe. For offshore line-pipe construction, the economic savings has been shown to be considerable, approaching a calculated 25%. Offshore pipe is relatively small diameter but heavy wall compared to onshore pipe. One concern is the ability to achieve consistent full weld penetration in an on-site offshore FSW operation, e.g., on a lay-barge. Further, depending on the size and morphology of the unwelded zone, lack of penetration at the weld root can be difficult if not impossible to detect by conventional NDE methods. Thus, an approach to assure consistent full penetration via process control is required for offshore line-pipe construction using FSW. For offshore construction, an internal structural mandrel can be used offering the opportunity to use a sacrificial anvil FSW approach. With this approach, a small volume of sacrificial material can be inserted into the structural anvil. The FSW tool penetrates into the sacrificial anvil, beyond the inner diameter of the pipe wall, thus assuring full penetration. The sacrificial material is subsequently removed from the pipe inner wall. In the work presented herein, FSW studies were completed on both 6 mm and 12 mm wall thickness line-pipe. Post-FSW evaluations including radiography, root-bend tests, and metallography demonstrated the merits of the sacrificial anvil approach to achieve consistent full penetration.

Because offshore plant industry needs to design, deploy and operate much of equipment especially, the latest trend shows the installation of production facilities is augmented in the subsea. The installed facilities are very difficult to be repaired or changed because they are located in the subsea. For solving these problems, both the directly related information of the production like the optimal number, position and depth of wells and the distribution for effective operation and safety of equipment of subsea should be considered at the preliminary stage of FEED (Front End Engineering Design). The marine exploration is introduced in this paper for providing the fundamental technology to answer the questions related to above considering points. First, some kinds of the offshore plant facilities are enumerated and aims of marine exploration for the offshore oil/gas development are summarized. In addition to it, the main roles of marine survey, in the step of designing and installing offshore oil-gas plant, development are briefly listed. And then foreign examples are shown to help the reader’s understand. This paper is hoped to be helpful for understanding the marine exploration that can be applied to offshore oil/gas plant and to be contributed to developing the domestic techniques in this field for the future.