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Purpose of the paper: The decommissioning of offshore platforms represents a significant and controversial challenge that has gained attention over the years due to its environmental, social, and economic impact. This work aims to investigate stakeholders’ perceptions regarding the future of offshore platforms and to explore dimensions of sustainability related to decommissioning. Methodology: An analysis was carried out based on two rounds of empirical inquiry, a range of primary data collected through multiple-choice questionnaires and in-depth interviews. Findings: The analysis shows that stakeholders perceive reuse as an opportunity to minimise the impacts according to an environmental, economic, and social perspective. While the multipurpose platform represents an opportunity for the future, it also presents challenges. Research limitations: The study relies only on qualitative analysis techniques and on a limited sample and geographical area. Practical implications: The analysis offers several insights into the decommissioning scenario according to a sustainable and circularity perspective and contributes to the decommissioning debate by providing information about decommissioning programs, stakeholders’ impacts, and future planning considerations. Originality of the paper: The study contributes knowledge to the field and useful managerial insights, highlighting stakeholders’ perception in the Italian context and exploring dimensions of sustainability and main SDGs related to the issue

Purpose This study aims to investigate the collective perception regarding the future of offshore platforms and frame the main categories of meanings associated by the community with the investigated phenomenon. Design/methodology/approach A data driven approach has been conducted. The collection of the peoples’ opinions has been realized on two specific social network communities as follows: Twitter and Instagram. The text mining processes carried out a sentiment and a cluster analysis. Findings The sentiment analysis of the most frequent words has been shown. The following four main homogeneous categories of words are emerged in relation to the decommissioning of offshore platforms: technological areas, green governance (GG), circular economy and socio-economic sphere. Research limitations/implications The alternative use of the offshore platforms, including tourism initiatives, aquaculture, alternative energy generation, hydrogen storage and environmental research, could improve the resilience of communities by offering the development of new jobs and the growth of local and innovative green businesses. Practical implications The adoption of a circular model and GG initiatives aims to limit the input of resources and energy, minimize waste and losses, adopt a sustainable approach and realize new social and territorial value. Originality/value The analysis underlines the importance to adopt a systems perspective, which takes into account the social, economic and environmental system as a whole, the different phenomena that occur and the variety of categories of stakeholders, from users to local governments that participate in the territorial development.

Vibration sensing is of great significance in offshore engineering monitoring and safety detection. This paper presented a low-frequency vibration sensor (LV-TENG) based on a cantilever-beam-structured triboelectric nanogenerator, which can perform high-precision vibration sensing while conducting vibration energy collection effectively. The LV-TENG was composed of two aluminum electrode layers, a spring steel sheet covered with polytetrafluoroethylene (PTFE) and a first-order vibration mode structured frame. Under the excitation of external vibration, the spring steel sheet undergoes first-order modal vibrations between the aluminum electrodes and generates a periodically fluctuating electrical signal in the external circuit. The vibration profile of the cantilever beam was first analyzed theoretically to provide guidance for structural design. On this basis, the influence of the main structural parameters, including the structure of the Al electrode, the thickness of the steel plate, and the electronegative materials, on the output performance of LV-TENG was experimentally investigated and the structure was optimized to enhance electrical output. The results showed that the LV-TENG can accurately sense structure vibration with a frequency of 0.1 Hz to 5.0 Hz and an amplitude of 2.0 mm to 10.0 mm. The measured output voltage followed a positive linear relationship with frequency and the fitted correlation coefficient reached 0.994. The demonstration experiment indicated that the LV-TENG is expected to provide a new avenue for low-frequency vibration monitoring and can be used for structural health monitoring analysis in marine engineering.

Biofouling is a natural phenomenon that consists of the accumulation of living organisms on an artificial surface submerged or in contact with water like Offshore platforms. This study highlights the need for offshore floating wind farms structures to consider the choice of material used in offshore applications to minimize microbial-associated and corrosion problems. For this purpose, differences in the total of seawater biofouling attached on two coated paints and three ceramic coatings in carbon steel for offshore structures were evaluated and compared. All ceramic coatings were made of incorporating, by electrophoretic deposition, active ceramic particles against biofouling as copper, silver, zinc and titanium. This experiment consisted of testing ceramic coatings and conventional paints in a real environment with high biological activity and at the same time in a shallow marine environment for a period of 1 year, which provided positive comparisons with the standard system (ASTM-D3623) for using in protecting offshore marine structures.

Over the last few years, enormous efforts have been made to improve the energy sector by enhancing sustainability. The application of sustainable design approaches, the selection of low-impact materials, waste recycling and reuse, among others, are all factors in the construction of offshore platforms. The examination of offshore platform sustainability performance, including the creation of quantification methodologies, indicators, and other metrics, has also been extensively researched around the world. Since energy is used in nearly every area of modern economies, it is regarded as a strategic asset. Apart from renewable generation sources, natural gas and oil are the most common fuels used to generate electricity. It's no surprise that recent challenges from commodity, stock, and credit markets, which have put natural gas and oil companies' operations in risk, have been a major topic of discussion in the academic literature, particularly in recent decades, when both markets have changed at an unprecedented rate due to changes in both supply technologies and energy demand characteristics. Natural gas and crude oil are normally competitors in the creation of power, but they are also alternatives for one another in consumption, resulting in price correlations. We welcome articles that examine the design and analysis of offshore structures, sustainable development, wind turbine design, oil and gas platform design, market reviews, literature reviews and research papers on the asset standpoint to be submitted to this special issue of Sustainability. We encourage research into the characteristics of different components of the oil and gas industry, from design, exploration and transfer, and related issues like oil spillage, oil recovery, carbon capture and geotechnical survey. Also, the economics (oil prices) in commodities markets, stock market prices for oil and gas companies, capital structure choices and funding alternatives used in the two sectors, and spillover effects between the two markets and from (to) these markets to (from) other financial markets is welcomed. Papers examining the geopolitical dynamics that impact natural gas and oil markets, marine law cases involving the oil & gas industry, oil & gas policies and legislations, as well as papers addressing the sector's future difficulties and uncertainties, from a variety of disciplinary perspectives, are also encouraged. This special issue of Sustainability aspires to become a future reference point for chronicling oil and gas industry, sustainable development, recent transformations and future paths. Novel designs/developments like a floating stadium, floating airports, floating offices, floating platforms and floating houses are part of sustainable developments, and can also be submitted. Hence, this Special Issue on the ���Analysis and Sustainable development of offshore structures���. The main goal of this special issue is to address the key challenges, thereby promoting research on offshore structures., Over the last few years, enormous efforts have been made to improve the energy sector by enhancing sustainability. The application of sustainable design approaches, the selection of low-impact materials, waste recycling and reuse, among others, are all factors in the construction of offshore platforms. The examination of offshore platform sustainability performance, including the creation of quantification methodologies, indicators, and other metrics, has also been extensively researched around the world. We welcome articles that examine the design and analysis of offshore structures, sustainable development, wind turbine design, oil and gas platform design, market reviews, literature reviews and research papers on the asset standpoint to be submitted to this special issue. We encourage research into the characteristics of different components of the oil and gas industry, from design, exploration and transfer, and related issues like oil spillage, oil recovery, carbon capture and geotechnical survey. The main goal of this special issue is to address the key challenges, thereby promoting research on offshore structures. I encourage you to contribute a research or comprehensive review article for consideration for publication in Sustainability, an international Open Access journal which provides an advanced forum for research findings in areas related to sustainability and sustainable development. The journal publishes original research articles, reviews, conference proceedings (peer-reviewed full articles) and communications. I am confident you will find the journal contributes to enhancing understanding of sustainability and fostering initiatives and applications of sustainability-based measures and activities. The submission deadline is 15th December, 2022.

The long dissolution time and large dispensed volumes of oil repellent polymers in offshore oil fields lead to a great increase in the volume and number of dissolution and maturation tanks in the polymer formulation system. However, there is limited space and load-bearing capacity at the offshore platform and only a small space is available for the dispensing system. To further optimize the polymer dispensing system and reduce its floor space, the super-gravity technology may be considered as a way to speed up the dissolution of the polymer. The mechanism of super-gravity rapid dissolution was investigated by establishing mathematical models and with indoor experiments. The effects of filler pore size and super-gravity factor on polymer dissolution time and solution viscosity were investigated using the super-gravity rapid dissolution device, then combined with established graded forced stretching devices for field magnification experiments. The results indicated that the super-gravity method can substantially shorten the polymer dissolution time. The basic dissolution time of the polymer AP-P4 was shortened by 35 min compared with the conventional formulation method after use of the super-gravity rapid dissolution device. The optimal process conditions for the preparation of polymer solution by the super-gravity rapid dissolution device were selected as the optimal super-gravity factor range of 1031~1298.

The work aims to improve the existing fast load shedding algorithm for industrial power system to increase performance, reliability, and scalability for future expansions. The paper illustrates the development of a scalable algorithm to compute the shedding matrix, and the test performed on a model of the electric grid of an offshore platform. From this model it is possible to study the impact on the transients of various parameters, such as spinning reserve and delay time. Subsequently, the code is converted into Structured Text and implemented on an ABB PLC. The scalability of the load shedding algorithm is thus verified, confirming its performance with respect to the computation of the shedding matrix and the usefulness of the dynamic simulations during the design phase of the plant.

Diverse forms of offshore oil and gas structures are utilized for a wide range of purposes and in varying water depths. They are designed for unique environments and water depths around the world. The applications of these offshore structures require different activities for proper equipment selection, design of platform types, and drilling/production methods. This paper will provide a general overview of these operations as well as the platform classifications. In this paper, a comprehensive review is conducted on different offshore petroleum structures. This study examines the fundamentals of all types of offshore structures (fixed and floating), as well as the applications of these concepts for oil exploration and production. The study also presents various design parameters for state-of-the-art offshore platforms and achievements made in the industry. Finally, suitable types of offshore platforms for various water depths are offered for long-term operations. An extension of this study (Part II) covers sustainable design approaches and project management on these structures; this review helps designers in understanding existing offshore structures, and their uniqueness. Hence, the review also serves as a reference data source for designing new offshore platforms and related structures.

This paper deals with the assessment of fatigue crack propagation on the connection between column and brace for a semi-submersible. The analysis of global and local structural responses under different sea states are performed to acquire the transfer functions of stresses. Based on an existing crack the Failure Assessment Diagrams (FAD) are applied as criterion of acceptance for the safety of crack and structure during the crack growth calculation cycle. The crack growth rate considering threshold stress intensity factor and stress ratio is used. During safety assessment the stress response from ultimate sea state is outlined. A comparison of fatigue crack growth using ultimate stress and normal stress data with different crack growth rate is presented. The results show the reliability of fatigue assessment using FAD as a measurement of acceptability of crack propagation.

Offshore structures exist in a variety of forms, and they are used for a variety of functions in varied sea depths. These structures are tailored for certain environments and sea depths. Different actions for suitable equipment selection, platform type design, and drilling/production processes are required for the applications of these offshore structures, as given in Part I. This paper is the second part, which outlines various processes, loads, design approaches and project management of offshore platforms. To achieve these, proper planning must be conducted for lifting, transportation, installation, design, fabrication, and commissioning of these offshore platforms. Some historical developments of some offshore structures are presented, and some project planning routines are undertaken in this research. The ultimate goal is to provide a general overview of the many processes of offshore platform design, construction, loadout, transportation, and installation. Some discussions on the design parameters such as water depth and environmental conditions were presented. It also lists various software programs used in engineering designs covering software programs for structural analysis, 3D rendering, computer-aided design (CAD), hydrodynamic design, oceanic flow analysis, offshore structures analysis, mathematical modelling, coding/algorithm development software, and programming software to aid analytical calculations. The review also includes information on cutting-edge offshore platforms and industry advancements. Ultimately, for long-term operations, various types of offshore platforms for specific seawater depths are available.

International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies, 11, 9, 11A9D: 1-12

The requirements for the fire resistance of steel structures of oil and gas facilities for transportation and production of hydrocarbons are considered (structures of tankers and offshore platforms). It is found that the requirements for the values of fire resistance of structures under hydrocarbon rather than standard fire conditions are given only for offshore stationary platforms. Experimental studies on the loss of integrity (E) and thermal insulating capacity (I) of steel bulkheads and deck with mineral wool under standard and hydrocarbon fire regimes are presented. Simulation of structure heating was performed, which showed a good correlation with the experimental results (convective heat transfer coefficients for bulkheads of class H: 50 W/m2·K; for bulkheads of class A: 25 W/m2·K). The consumption of mineral slabs and endothermic mat for the H-0 bulkhead is predicted. It is calculated that under a standard fire regime, mineral wool with a density of 80–100 kg/m2 and a thickness of 40 to 85 mm should be used; under a hydrocarbon fire regime, mineral wool with a density above 100 kg/m2 and a thickness of 60–150 mm is required. It is shown that to protect the structures of decks and bulkheads in a hydrocarbon fire regime, it is necessary to use 30–40% more thermal insulation and apply the highest density of fire-retardant material compared to the standard fire regime. Parameters of thermal conductivity and heat capacity of the applied flame retardant in the temperature range from 0 to 1000 °C were clarified.

Multi-purpose offshore structures are very complex systems to be designed as many different requirements have to be taken into account simultaneously. Experimental tests on scaled models can be very useful to verify structural behavior and to validate numerical models. The definition of the scale can play a key role in performing tests as high scales, closer to full-scale, are generally related to more reliable results. The present paper concerns the design of a wind turbine model for a large-scale model of a Multi-purpose offshore Platform developed within the EU project H2020 Blue Growth Farm. This project aims at developing an offshore farm, based on a modular floating structure that integrates wave energy converters and a wind turbine with aquaculture. The scale model of the complete structure will be deployed at the Natural Ocean Engineering Laboratory (NOEL). The paper will focus on the strategies adopted to scale 1:15 the DTU 10 MW wind turbine in order to represent both the main aeroelastic features and all the functionalities of a real machine. The complete design of the machine and its control will be also provided.

The growing complexity of environmental challenges has progressively led to the emergence of Sustainable Business Models (SBMs) able to embed economic, environmental, and social flows in a unified value network. All sectors are demanding innovative and sustainable solutions, including the oil and gas industry, which aims to address the issues about the decommissioning of offshore platforms. However, although the relevant literature highlighted the potentialities related to a multi-reuse of these structures, the effect of Sustainable Decommissioning (SD) on macro-environmental factors is still an open question. Based on these considerations, this study follows a Political, Economic, Social, Technological, Legal, and Environmental (PESTLE) analysis according to semi-structured interviews conducted with oil and gas key informants and stakeholders in the Italian context. The results of the analysis can provide a novel thinking for addressing the challenges related to a sustainable decommissioning of offshore platforms and shed light on the importance of synergistic efforts by local entrepreneurship and institutional arrangements to combine economic and environmental sustainability with social needs. This paper can contribute to the emerging field of sustainable business models related to the decommissioning of offshore platforms and suggests avenues for future research.

The offshore plant, due to its characteristics, is subject to many restrictions on the material and design of the pipes. Because the design of the firefighting piping depends on the pre-set fire protection design, it is possible to reduce the cost of the piping design by optimizing the arrangement of the firefighting equipment. Existing studies have low accuracy in obtaining service areas under these conditions. In addition, the arrangement optimization problem is generally modeled as a set cover problem (SCP). However, except for the traditional greedy approximation, this problem is not well researched for general solutions. In this paper, first, a modified iterative-deepening search (MIDS), which accurately obtains a service area according to the travel distance in the grid space, is proposed before optimization. Additionally, this paper seeks to define a set cover problem by combining the subsets obtained by MIDS. Second, by using the traditional greedy algorithm, we obtained the initial arrangement of the firefighting equipment. Then, we proposed a method to obtain an approximate optimization solution using a modified greedy method including rearrangement. The validity of the proposed coverage area acquisition and arrangement optimization method is verified by comparing the performance with other algorithms. Finally, this study was applied to the drawings of an actual offshore platform.

The high-efficient development of heavy oil is difficult for offshore oil field. Based on the mature technology of onshore heavy oil thermal recovery, a new rod pumping technology of “heavy oil steam stimulation along with conventional sucker rod pumping system” is proposed. According to the structure space of aimed offshore platform, we designed one new kind of miniature hydraulic pumping unit with long-stroke, low pumping speed and compact structure. The paper also studies the offshore heavy oil thermal recovery well safety technology, establishes a leakage model of wellhead sealing and a mechanical model of sealed rubber sleeve on downhole nonlinear large deformation. The study shows that a series of equipment for offshore rod pumping oil recovery and the key technology of well safety lay a solid foundation for carrying out rod pumping of offshore heavy oil thermal recovery.

Grouted connections are frequently used as structural detail of offshore wind turbines and platforms for the load transferring connection between piles and support structure. At latticed substructures this connection is commonly located at mudline. However, a potential influence of the surrounding water on the connection's fatigue behaviour was neglected in earlier tests and consequential design methods. Herein described experimental investigations at small and large-scale fatigue tests in submerged conditions showed a significant reduction of endurable load cycles. In addition, the water impact caused varied damage mechanism in the connection. © 2017 The Author(s).

Object and purpose of research. This study is dedicated to formation control of salt deposits polluted by natural radionuclides inside flow columns of subsea wells. The purpose of the study is to determine the optimal set of prevention measures for further salt deposit formation within the entire production system of an offshore oil & gas production rig. Materials and methods. Compact instrumentation & calculation hardware installed on pipes, as well as measurement and data processing algorithm for early detection of radioactive salt deposits inside flow columns. Main results. The study suggests equipment and a radiometric method for early detection of salt deposits inside flow columns, as well as demonstrates early detection possibility for 1-2 mm thick salt deposit containing Tl-208 with minimum specific activity of ~0.15 Bq/g, with reliable detection probability 1-β = 0.9 at false alarm level α = 0.01. Application of detection units with BGO or CsJ(Tl) will enable detection of even thinner radioactive salt deposits. Conclusion. The possibility to detect salt deposits at early stages, without interruption of the production process and, consequently, without production loss, as well as the possibility to promptly inform the operator of the platform’s main control room about the beginning of salt deposit formation will make it possible to launch the optimal strategy of combatting further salt deposit development in pipeline and equipment of the entire production system of the platform.

The data were collected through inspection of ROV videos. The data are formatted in a single csv file. It contains 30 columns with 5587 rows, including title row. Each row represents a separate observation of species abundance according to the Braun-Blanquet scale. The dataset contains null values which are indicated with NA. The first 21 columns contain sample information. Columns 22-29 contain information about taxonomic grouping and Column 30 contains the Braun-Blanquet abundance values.

International audience; Tensegrity systems are a class of reticulated space structures composed of compressed bars maintained in equilibrium by a network of tensioned cables. Their stiffness depends both on elements’ mechanical properties and their internal self-stress state. Taking advantage of their structural properties, we respond to the challenge of accessibility for everybody to the sea with a new concept of modular lightweight and deployable platforms. Variable configurations are developed to fit ecologically into the marine environment thanks to the transparency of double layer tensegrity structures. Moreover, allowing practical assembly and disassembly is considered in the design to respect the coastal law. Through a numerical study, we demonstrate in this paper the capability of this solution under various representative load cases and support conditions.After the structural and design optimization of elements constrained by weight and stiffness, we detail the design of the nodes, which are the key components ensuring geometry and foldability of the structure. Finally, on-site setting and interfacing with ground supports is experimented in marine conditions to proof the feasibility of this concept.

Multi-use offshore platforms (MUPs) combining renewable energy from the sea, aquaculture and transportation facilities can be considered as a challenging way to boost blue growth and make renewable energy (especially wave energy) environmentally and socio-economically sustainable. MUPs allow sharing the financial and other market/non-market costs of installation and management, locally using the produced energy for different functionalities and optimizing marine spatial planning. The design of these solutions is a complex interdisciplinary challenge, involving scientists and technical experts with different backgrounds. This paper presents a new methodology for the design of a MUP based on technical, environmental, social and economic criteria. The methodology consists of four steps: a pre-screening phase, to assess the feasibility of different maritime uses at the site; a preliminary design of the alternative schemes based on the identified maritime uses; a ranking phase, where the performance of the MUPs is scored by means of expert judgment of the selected criteria; a preliminary design of the selected MUP selected. An example application of this procedure to a site offshore the Western Sardinia coast, Mediterranean Sea, Italy, is provided. In this site the deployment of a MUP consisting of wave energy converters, offshore wind turbines and aquaculture is specifically investigated.

To improve the anti-explosion performance of blast wall in offshore platforms, an auxetic re-entrant blast wall (ARBW) was proposed and designed based on the indentation resistance effect of an auxetic structure. Based on the numerical nonlinear dynamic analysis method verified by the explosion experiment of a conventional steel corrugated blast wall (CBW), the failure mechanisms of ARBW, steel honeycomb sandwich blast wall (HSBW) and CBW were investigated under distributed impulse loads. Computational results demonstrated the excellent anti-explosion performance of the proposed ARBW design. Concerning the minimal deformation at the mid-point of the proposed protective structures, the ARBW performed best. As regards the minimal deformation at the connection, both ARBW and HSBW worked well. The stress distribution of the connection illustrated the different energy absorption and transmission modes of the three blast walls.

This paper documents developments in fatigue cracking of a floating platform that required repair and upgrading during 1999–2000. The Veslefrikk B (VFB) platform was built in 1985 for drilling exploration but was converted to a production platform in 1989. Shortly thereafter extensive fatigue cracking was discovered and several repairs were made. However, extensive fatigue cracking continued and a retrofitting program was implemented, using various types of grinding and peening techniques. In 1999 the platform was temporarily decommissioned and dry-docked for a comprehensive repair and upgrading program, following the International Institute of welding (IIW) guidelines for weld improvement methods [1] , this was completed in only four months. However, after a few more years of service fatigue damage again necessitated new repairs. The majority of cracks occurred in the hull skin plates and caused water leakage. It is noteworthy that cracking this time occurred only in areas of the structure that were left untreated in the first retrofitting program due to low levels of stress from FE analyses in these areas. The paper describes the original repair and strengthening program, and the types of subsequent fatigue damage that necessitated new repairs. The recent life extension program has resulted in the safe operation of the platform for an estimated additional period of 20 years.

Estimation of wave run-up has been of increasing concern for offshore wind structures and a critical aspect for designers. The highly nonlinear phenomenon makes the study difficult. That is the reason for the very few design rules and experimental data available to estimate it. Actual wave run-up is greater than commonly predicted. The goal of this research is to benchmark the theoretical formulations with the results of the physical model tests performed by Deltares in the field of crest elevation, run-up, forces and pressures. The laboratory reproduced in a wave tank (75 m length; 8.7 m width; 1 m depth; and a 1:60 scale, with Froude similarity) an offshore power converter platform located at intermediate water depths (25–43.80 m) in the Southern North Sea, designed by the Norwegian company Aibel. The purpose of this research is to offer a preliminary design guide for wave run–up using theoretical expressions both for cylinders and gravity based structures (GBS), leaning on the cited laboratory tests to validate the results obtained by such theoretical models. This research was funded by La Caixa PhD Program Fellowship.

This data was collected to determine whether the composition and the abundance of species assemblages changes with depth and along a distance from shore gradient. The species assemblage on offshore gas platforms in the Dutch part of the North Sea was inventoried using ROV inspection footage. The dataset contains observations of 11 species on 5 of these platforms.

This paper describes a group model building activity designed to elicit the potential effects a projected multi-use deep water offshore platform may have on its local environment, including ecological and socio-economic issues. As such a platform is proposed for construction around the island of Hsiao-Liu-Chiu, Taiwan, we organized several meetings with the local stakeholders and structured the debates using group modeling methods to promote consensus. During the process, the participants iteratively built and revised a causal-loop diagram that summarizes their opinions. Overall, local stakeholders concluded that a multi-use deep water offshore marine platform might have beneficial effects for Hsiao-Liu-Chiu because more tourists and fish could be attracted by the structure, but they also raised some potential problems regarding the law in Taiwan and the design of the offshore platform, especially its resistance to extreme weather. We report the method used and the main results and insights gained during the process.

WOS; International audience; In offshore tubular structures, a typical tubular joint may be subjected to three different types of basic loadings: axial, in-plane bending and out-of-plane bending, through its brace members. Each type will cause a different stress distribution at the joint intersection of structures. Moreover, the actual load condition of a tubular joint can be any combination of the above three basic load cases, for this reason, a combined loading was investigated in addition to these three basic loadings. This load is composed of an axial loading combined with a continuation of rotational bending loading obtained while rotate center of the brace around a circle. Different types of planar joints such as T, Y, X, K, DT, DY, DX, TY, TK, DTX, DTDY, and DTDK, with braces subjected to combined loading, were numerically analyzed to study the effect of those different cases of loading and different types of joints, on the stress concentration zone and values.

Role of mini tension leg platforms (TLP) in oil exploration and production in marginal deepwater fields is becoming increasingly important. Mini TLP combines the simplicity of a spar and favorable response features of a TLP. In this paper, the results of a detailed experimental and numerical investigation of the coupled dynamic behavior of a mini TLP are reported with special attention to hull-tether coupling. The experimental study has been carried out using a scaled model in wave flume with specially designed tethers whose first two "string" natural frequencies are excited by waves, thus achieving strong hull-tether coupling. The numerical study has been carried out using a nonlinear time domain finite element method specifically addressed to compliant offshore platforms using a combination of potential theory based wave loading and Morison-type wave loading. Extensive comparisons between numerical and experimental results have been made both for platform motions and deflected shapes of the tethers and conclusions drawn. Copyright ? 2004 by ASME.

Offshore drilling raises the issue of disposal of platforms at the end of their productive cycle and re-use as artificial reefs has been proposed. The wreck of the "Paguro" drilling platform, which sank in the northern Adriatic Sea in 1965, offers the opportunity to study the performance of offshore structures as artificial reefs in a region where this solution has not been explored before. We provide a description of the macrobenthic assemblages present at the wreck at different sites and at different depths, based on destructive and photographic sampling. Results show that the wreck has been colonized by a rich and diversified fauna. Primary space has been dominated by mussels and oysters, which provide suitable habitats for a variety of benthic invertebrates. Assemblages vary among sites, species richness is greatest at those sites facing prevailing currents. Distribution patterns vary vertically, evenness (Hill's N10) decreasing significantly with depth. It is argued that the results contribute to the background knowledge required in rigs-to-reefs programmes. © 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.

TNT Equivalency methods are widely used for vapour cloud explosion blast modeling. Presently, however, other types of models are available which do not have the fundamental objections TNT Equivalency models have. TNO Multi-Energy method is increasingly accepted as a more reasonable alternative to be used as a simple and practical method. Computer codes based on computational fluid dynamics (CFD) like AutoReaGas, developed by TNO and Century Dynamics, could be used also in case a more rigorous analysis is required. Application of the Multi-Energy method requires knowledge of two parameters describing the explosion: a charge size and a charge strength. During the last years, research has led to an improved determination of the charge strength (i.e., the class number or source overpressure) to be chosen to apply the blast charts. A correlation has been derived relating the charge strength to a set of parameters describing the boundary conditions of the flammable cloud and the fuel in the cloud. A simple approach may not be satisfactory in all situations. The overpressure distribution inside a vapour cloud explosion is generally not homogeneous and the presence of obstructions causes directional blast propagation in the near field. A CFD approach, in which the actual situation is modeled, supplies case-specific results. An overview of the key aspects relevant to the application of the Multi-Energy method and CFD modeling is provided. Then the application of the two methods is demonstrated for an example problem involving the calculation of the explosion blast load on a structure at some distance from the explosion in an offshore platform complex. Copyright (C) 2000 Elsevier Science B.V.

Fossil fuel is not practically renewable and therefore the world is at risk of fossil fuel depletion. This gives urgency to investigate alternative energies, especially for industries that rely entirely on energies for operations, such as offshore industry. The use of alternative energies in this industry has been in place for a while now. This paper discusses the application of various alternative energy sources to assist powering the Goodwyn Alpha (A) Platform, located on the North West Shelf (NWS) of Australia. The three alternative energy sources under discussion are: wind, wave and solar. The extraction devices used are the Horizontal and Vertical-Axis Wind Turbines - for wind; Pelamis, PowerBuoy and Wave Dragon - for wave; and the solar parabolic dish of SunBeam and Photovoltaic (PV) cells of SunPower - for solar. These types of devices are installed within the same offshore platform area. Technical, environmental and economic aspects are taken into consideration before the best selection is made. The results showed that PowerBuoy used for wave energy, is the best device to be used on offshore platforms where operators could save up to 9% of power; $603,083 of natural gas; and 10,848 tonnes of CO2 per year.

On conventional offshore petroleum platforms, the combined heat and power production (CHP) currently depends on simple cycle gas turbine systems (SCGT) that operate at lower efficiency and increased environmental impact compared to modern onshore thermoelectric plants. Additionally, the reduced space and the limited weight budget on offshore platforms have discouraged operators from integrating more efficient, but also bulkier cogeneration cycles (e.g. combined cycles). In spite of these circumstances, more stringent environmental regulations of offshore oil and gas activities have progressively led to a renewed interest in the integration of advanced cogeneration systems, together with either customary or unconventional carbon capture approaches, to maintain both higher power generation efficiencies and reduced CO2 emissions. Thus, in this paper, it is evidenced how advanced gas turbine concepts are promising technologies for maintaining or even increasing efficiency, while facilitating the capture rate of CO2 produced, either for geological storage or enhanced oil recovery. Despite the profuse research works on onshore applications, advanced cogeneration and carbon capture systems have been barely studied in the context of supplying power to offshore petroleum platforms. Accordingly, the performance of a conventional offshore petroleum production platform (without carbon capture system) is compared to other configurations, based on either an amine-based chemical absorption system or oxyfuel combustion concepts ( S-Graz and Allam cycles) for CO2 capture purposes. Since the original power and heat requirements of the processing platform must remain satisfied, an energy integration analysis is performed to determine the waste heat recovery opportunities. Additionally, the exergy method helps quantifying the most critical components that lead to the largest irreversibility and identifying the thermodynamic potential for enhanced cogeneration plants. As a result, oxyfuel equipped platforms provide a diversified set of advantages, while keeping competitive efficiencies. For instance, advanced systems allow for cutting down ostensibly the atmospheric CO2 emissions compared to the conventional and amine-based power plant configurations of the FPSO.