Construction Of Offshore Platforms Research Articles

Point-to-Point-Based Optimization Method of Ballast Water Allocation for Revolving Floating Cranes with Experimental Verification

The Revolving Floating Crane (RFC) is a specialized engineering vessel crucial for offshore lifting operations, such as offshore platform construction and deep-water salvaging. It boasts impressive lifting capacity, good adaptability to various environmental conditions, and high operational efficiency. Conventionally, the safety and stability of RFC operations heavily depend on manual ballast water allocation, which is directly influenced by factors such as personnel status and sea conditions. These manual operations often result in reduced lifting efficiency, higher energy consumption, and compromised operational safety. In response, this paper introduces a ballast water-allocation approach based on the Point-to-Point (PTP) theory for the intelligent operation process of the RFC. The fundamental principles of the PTP theory are analyzed, and a method tailored to optimize ballast water allocation for RFC is proposed. Considering the unique characteristics of the ballast system and the specific requirements of lifting operations, an optimization model for PTP-based ballast water allocation is established. Numerical experiments are conducted to verify the efficacy and reliability of the proposed method. Comparing it to the conventional approaches, the results demonstrate a notable 17.75% reduction in energy consumption and an impressive 73.49% decrease in decision-making time, showcasing the superiority of the proposed approach. Finally, the engineering feasibility of the PTP-based optimization method for ballast water allocation is validated through actual lifting experiments, underscoring its potential to enhance RFC operations.

Simulating Leakage Impact on Steel Industrial System Functionality

Steels exhibiting ultralow sulfur content tend to gain increasing usage or application in manufacturing pipes used in oil transportation, as well as offshore platform construction. For these systems or platforms, it is worth indicating that they call for high resistance and impact strength relative to the formation of lamellar cracks. In this study, it was documented that when a refinery is compromised, the resultant fluids that are released tend to cause a loss in the refinery’s transportation capability. This outcome suggests that there is likely to be a decrease in the efficiency of transmission. Notably, the study examined the extent to which a leak presence affects flow behavior in the context of annular mist flow regime’s deep water production flow line. Another context that was investigated involved slug and stratified flow regimes. From the results, given the slug and annular flow regimes, any leakage could alter the pattern of material flow.

A hybrid algorithm for the variable-sized bin-packing problem of pipe cutting in offshore platform construction

A hybrid algorithm for the variable-sized bin-packing problem of pipe cutting in offshore platform construction

Failure Criteria and Wind-Induced Vibration Analysis for an Offshore Platform Jacking System

Currently, the construction process of large offshore platforms worldwide involves building the topside and hull separately and then having them integrated. Jacking technology is emerging as a new integration method more suitable for offshore platform construction for its higher tonnage and larger scales compared with the lifting technology. Conventionally, an overlapped support tower (OST) is adopted to jack the topside to a predetermined height. However, with the OST’s increasing jacking height, the wind load effect becomes more significant, which in turn limits the OST height and applications. In this paper, failure criteria were developed for the OST based on the load types and structural characteristics of easy assembly and disassembly. Then a simplified method to simulate the OST was proposed. In addition, a finite element model (FEM) of the entire jacking system with the topside and OST (including 6 jacking towers, 8 strand cables and 23 bracing pipes) was established, and wind-induced vibration analysis was performed to ensure safety of the jacking system. The results show that the addition of the topside increases the torsional effect of the jacking system; the unfavorable wind angles are 0° and 15°, which should be paid much attention during the jacking operation. The recommended wind-induced vibration coefficients for the OST and topside are 3.0 and 4.0, respectively. The proposed method and simulation results of this study provide a reference for the jacking and integration design of similar offshore platforms.

Study of the Bearing Capacity at the Variable Cross-Section of A Riser-Surface Casing Composite Pile

Reducing the cost of offshore platform construction is an urgent issue for marginal oilfield development. The offshore oil well structure includes a riser and a surface casing. The riser, surface casing and oil well cement can be considered special variable cross-section piles. Replacing or partially replacing the steel pipe pile foundation with a variable cross-section pile to provide the required bearing capacity for an offshore oil platform can reduce the cost of foundation construction and improve the economic efficiency of production. In this paper, the finite element analysis method is used to investigate the variable cross-section bearing mode of composite piles composed of a riser and a surface casing in saturated clay under a vertical load. The calculation formula of the bearing capacity at the variable section is derived based on the theory of spherical cavity expansion, the influencing factors of the bearing capacity coefficient Nc are revealed, and the calculation method of Nc is proposed. By comparing the calculation results with the results of the centrifuge test, the accuracy and applicability of the calculation method are verified. The results show that the riser composite pile has a rigid core in the soil under the variable cross-section, which increases the bearing capacity at the variable cross-section.

СУЧАСНІ ТЕНДЕНЦІЇ ВИРОБНИЦТВА КОРОЗІЙНОСТІЙКОГО І ВОГНЕСТІЙКОГО НАПРУЖЕНОГО АРМАТУРНОГО ПРОКАТУ

The aim of the work is to study modern methods of production in the world of corrosion-resistant and fire-resistant high-strength reinforced rolled steel, designed for pre-stressed reinforced concrete structures. The specific cost of reinforcement is determined by the ratio of its value to the design resistance and decreases with increasing strength class. In Ukraine, economically alloyed steel grades are used for the production of prestressed high-strength reinforcing steel with a diameter of 6-40 mm of periodic profile according to DSTU 3760: 2019. It is also possible to use thermal strengthening of rolled products from rolling heating in the rolling mill stream, or from special (separate) heating. Hardening, tempering and also cold deformation of smooth profiles with the subsequent drawing of a periodic profile are also applied. According to the Interstate GOST 34028-2016 for the countries of the Customs Union, high-strength reinforcing steel of periodic profile of class A600p is made in bars and skeins with a diameter of 10-40 mm, and classes A800 and A1000 only in bars with a diameter of 10-40 mm from low-alloy steel grades. Depending on the diameter of the reinforcing steel, different production methods are used. GOST 34028-2016 contains clear requirements for corrosion resistance and methods of its testing. Many foreign requirements for the production of high-strength prestressed reinforcement, depending on the diameter of the profile (6-50 mm) and the method of production use carbon steels with different maximum carbon content from 0.37 to 0.8%, maximum silicon content from 0.55 up to 2.0% and a maximum manganese content of 1.8 to 2.0%. Thermomechanical reinforcement of reinforcing steel from rolling heating in the flow of rolling mills, hardening from separate (special) heating followed by tempering and strengthening by mechanical extraction followed by low-temperature tempering are used. Corrosion is the main cause of damage and destruction of reinforced concrete structures and buildings of prestressed reinforced steel from carbon steels. This problem in the world today is solved with the use of stainless steels, which have high corrosion resistance and fire resistance. Prestressed stainless steel reinforcement has higher strength and, especially, ductility than carbon steel. Stainless steel grades are used for the production of prestressed reinforcing steel with a diameter of 5 to 75 mm. In the production of periodic profiles of stainless steel reinforcement, there are two main technological routes: hot rolling and cold rolling. A promising way is the use of controlled hot rolling and thermomechanical treatment. As the rolling temperature decreases, the hardness of the austenite phase increases. For two-phase stainless steels, this allows to achieve high strength and ductility. Examples of the use of prestressed high-strength rebar in the world are: the construction of sealed shells that prevent the release of radioactive substances into the environment in severe accidents at nuclear power plants; construction of tanks for nuclear waste; construction of offshore platforms for oil production; construction of sea and river bridges, long-span ceilings, high-rise buildings, roads and other similar facilities.

COVID-19에 따른 SAJ 선박건조계약상 관련 불가항력 조항 적용 가능성에 대한 연구

Domestic shipyards should consider risk factors such as infectious diseases such as COVID-19, MERS, etc., currency exchange rate changes, global economic plunge, war, and strikes in the course of completing new ship building related to individual projects as new projects such as eco-ship, the emergence of Maritime Autonomous Surface Ships, the installation of offshore wind turbines, and the complexity of marine unmanned vehicles under IMO 2020. Therefore, the shipowner and the shipyard, which are key parties to the ship building contract, must carefully examine the scope, subject and conditions of the force majeure clause to prepare for future risks. However, officials from shipyards, finance, shipbuilding and marine equipment companies, law firms, and academia, which are linked to the new shipbuilding orders, have conducted considerable reviews of toxic clauses related to shipping or offshore platform construction contracts in the past, but have not conducted relatively in-depth research on the provisions of Force Majeure. It also fails to process or specify that, in the event of unforeseen circumstances, such as COVID-19, There is a legal difference in the scope of granting exemption from contractual liability by Force Majeure, depending on whether the governing law is continental or common law. Therefore, this study attempts to analyze the applicability of the Force Majeure Clause in the Contract of the SAJ through a legal review of the Force Majeure Providence Clause contained in the SAJ, which applies the Strict Liability principle of the Contract under the common law. And by analyzing the legal issues between the shipowner and the shipyard related to COVID-19, the company tries to find the risks and improvements that domestic shipyards will bear in the future.

Effect of geometric parameters and combined loading on stress distribution of tubular T-joints

Steel tubular structures are widely used in the construction of offshore platforms and T-type junctions are extensively used in this domain. The tubular members are welded, which generates significant stress concentrations at the edges. The stress levels reached in these critical places are used to assess lifetimes based on fatigue curves from tests conducted on standard samples. This study is devoted to the modeling and analysis of T-type welded tubular structures for the determination of hot spots stresses (HSS) at the chord/brace intersection, A numerical analysis was carried out to study the effect of a combined loading composed of an axial loading and a continuation of rational bending, that best assimilate real conditions, as well as the effect of normalized geometric parameters α, β, g on the distribution of stress concentration (area and values) of T-joints. The mechanical behaviour has been modeled in 2D using quadrangular and triangular thin-shell elements by the finite element method (FEM). It is the most appropriate approach because it considers all geometric complexities and singularities of the structure, while the efforts as well as the computation time are considerably reduced compared to an experimental study or to complex FE models implementing solid elements. In this study, we use the COMSOL-MULTIPHYSICS® software...

Solid waste management in Mexico’s offshore platform construction: determining potential supply for a reverse logistics process

One of the UN Millennium Development Goals (MDG's) is to ensure environmental sustainability. This has led international agencies to regulate the generation of waste, specifically solid waste, which is an issue of international significance. This research is an analytical, statistical, historical and deductive investigation that focuses on the management of municipal solid waste and special handling waste (SHW), specifically, the one generated in the construction of offshore platforms in Mexico. A comparative analysis of the waste generated domestically and in the construction of offshore platforms is done. This work proposes the introduction of a third party operator that, through reverse logistics, would develop strategies to recover, reuse or recycle SHW. The level of compliance of the Waste Management Plans of platform construction companies in Mexico is also analyzed. Currently, nine construction companies distributed in the states of Tabasco, Tamaulipas and Veracruz are building offshore platforms in Mexico. Particularly, the south zone of Tamaulipas has become, since the seventies, the largest provider of offshore platforms. These companies are required by law to report the amount of municipal solid waste and SHW that they generate. However, when analyzing the data provided, results show a great area of opportunity. With a proper management of waste, its recovery and/or disposal would be much more efficient. Data collected in the yards of construction is presented, as well as the current situation of the waste in the offshore platform construction industry and possible methods to strengthen environmental policy in solid waste in Mexico.

Wave Forces on Linear Arrays of Rigid Vertical Circular Cylinders in Regular Waves

The present investigation aims to experimentally determine the variation of forces and force coefficients acting on circular cylinders, which are arranged in a linear array along the direction of the waves. Most commonly used structural and non-structural elements in the construction of offshore platforms are circular cylindrical members. In many cases, these members are found in very close neighbourhood of each other, thus modifying the surrounding flow and wave forces acting on them. Model tests were conducted in the wave tank on a maximum of four cylinders of the same diameter. A reasonable scale factor was chosen considering the pertinent factors such as water depth, wave generating capability and accuracy of measurements. The cylinders were installed inside the wave tank as vertical cantilevers fixed at the top. Wave forces acting on the cylinders were measured using special wave force sensors exclusively designed and fabricated for the present project, while the wave profiles were recorded using wave probes installed in the wave basin. The results confirmed the presence of a force shielding effect on the trailing cylinders by the leading cylinders with few exceptions. The findings also substantiated the significant modification of the forces on cylinders when they are present in a linear array. A common practice adopted for the design of offshore platforms was identified with a possibility of underestimating the wave forces acting on the cylindrical elements. In many cases, the experimentally computed hydrodynamic force coefficients were found to be lower than the standard values adopted by various design codes. These findings portray the significance of the present work in achieving economy in the design of jacket platforms and risers.

Study on Pile-Soil Interaction during Pile Sinking and Drivability of Pile in Offshore Platform

The main mode of pile-soil interaction and the influence factors of pile sinking in offshore platform construction were analyzed and discusses the reasons that penetration resistance increases after stop driving and then continue. To study the drivability of piles of specified driving hammer, taking a jacket platform of Bohai Sea for instance, the results showed that continuous driving will make the open-end steel piles be driven to the designed depth, and driven-on will cause soil plug and pile driving refusal. Based on the results, the paper gives some suggestions about pile driving.

Experimental Study on CTOD Fracture Toughness of Welded Joints of Low Temperature Steel

According to BS7448 fracture toughness test standard, crack tip opening displacement (CTOD) for ASTM A333 Gr.6 low temperature steel which is used in offshore platform were carried out in low temperature (0°C, -29°C). Three point bending tests were conducted on the specimens, the dimension of which is B×2B (B is the thickness) and notch direction is NP. The final value of CTOD was calculated by P-V curves of both the welds and HAZ (heat affected zone). And the experimental results were analyzed and discussed in the paper. The low temperature steel welded joints show good low temperature toughness, the selected welding procedure is applied to construction of pipelines.The CTOD value of HAZ is larger than weld metal and weld is the weakest position in the whole structure. The experiment results provide an important basis for the choice of welding method and welding process parameters, ECA assessment and construction of offshore platform.

Análisis de la etapa actual de la Industria Marítima Brasilera y estudio de las características del agrupamiento en esta industria – La industria de la construcción naval, reparación, en altamar y náutica

The present work aims to analyze the Brazilian maritime industry. The core of the work is making an analysis of which are the basic elements to insert this system in the national maritime industry and how it is structured nowadays. The focus of the work is to analyze the four larger segments of this industry in Brazil: shipbuilding, construction of off-shore platforms and ship repair. The research included fieldwork in each national shipyard and other actors in the supply chain of that industry, as well as unions and associations.

Socio-economic effects monitoring: toward improvements informed by bio-physical effects monitoring

In this paper, using two case studies from the Hibernia offshore platform construction project, we argue that follow-up based on the hypothesistesting approach typically adopted in biophysical effects monitoring could be more widely adopted in socio-economic effects monitoring. While there are some significantly different issues associated with socio-economic and biophysical monitoring, we argue that such an approach in the socio-economic context would encourage more focused attention on monitoring objectives, more appropriate data collection and clearer identification of project-specific impacts, thereby offering more credible and useful information to decision-makers than is now often the case.

Arithmetic robot modules control robotic production

Discusses the forthcoming installation of an ABB Flexible Automation beam preparation system at an offshore platform construction company in Scotland. Using a six‐axis robot suspended from a boom, the system will be able to cut beams to any length with any desired end profile using an Arithmetic Robot Application Control [ARAC] system, which allows virtually any beam profile to be programmed into the system, in seconds by means of ARAC macros. Prior to cutting, the robot will exchange its gas torch for a 3‐D probe to measure the actual beam dimensions and compare these with the stored data design. Describes how the ARAC software package works and gives examples of other applications such as the cutting of round tubes for structural assemblies, multi‐pass welding and tube‐to‐sheet welding.

Construction of offshore platforms

Construction of offshore platforms

Construction of Offshore Platforms

The size and weight of offshore platforms have increased steadily as the search for oil and gas moves into deeper water and more hostile environments. This growth is portrayed in terms of water depth record setting projects. The capabilities and limitations of conventional construction techniques and equipment are described along with their impact on the fabrication and erection phases at construction. In the past five years, three offshore platforms have been installed in water depths approaching 1000 ft (305 m) and more with each project utilizing a different installation concept. The relationship between each of these concepts and the capacities of available equipment are explored. Future developments in water depths greatly exceeding 1000 ft (305 m) will utilize the compliant structural concepts, which require radically different installation procedures and more sophisticated equipment.

Platform Construction From an Adjacent Semisubmersible Vessel

Edwards, W.R., Occidental Petroleum (Caledonia), Ltd. Semisubmersible support barges (SSSB) alongside platforms in the North Sea have made year-round construction 95% available. This concept was used successfully to develop the Piper and Claymore fields. A checklist is given for outfitting SSSB's for construction support. Introduction Traditionally, offshore platform construction has occurred from an adjacent vessel since the first platform was installed in the Gulf of Mexico in 1946. As platform size and complexity increased, so did the requirements for construction support. Fortunately, the normally placid waters of the Gulf of Mexico permitted use of placid waters of the Gulf of Mexico permitted use of conventional barge hulls for this service, with sufficient reliability to complete programs continuously. The advent of exploratory drilling in the North Sea caused the evolution of more refined versions of the column-stabilized semisubmersible hull with which to conduct those drilling programs reliably. These units are designed to continue drilling in 35-ft seas and to keep station in waves of up to 100 ft. Unfortunately, vessel designs suitable for extensive rough-water platform construction have not kept pace with those for drilling, with the result that offshore construction programs were designed to be completed in the more predictable summer "weather window." This sort of planning requires duplicate provisions for personnel, systems, and equipment to assure timely completion, with resultant escalating costs and operational inefficiencies. Perhaps a classic example of the need to extend the weather window into year-round operation was the installation of Occidental Petroleum (Caledonia) Ltd.'s North Sea Piper platform jacket. Petroleum (Caledonia) Ltd.'s North Sea Piper platform jacket. This program was an early offshore effort by the Occidental consortium to develop their Piper and Claymore North Sea fields. This consortium - comprising Occidental Petroleum Corp. (36.5%), Getty Oil International (England) Ltd. (23.5%), Thompson Scottish Petroleum, Ltd. (20%), and Allied Chemical (North Sea) Ltd. (20%) - acquired the Piper Block (U.K. 15/17) and the Claymore Block (U.K. 14/19) in March 1972, and began an aggressive exploratory drilling program that resulted in discovery and definition of these two fields in 1973-74. Piper and Claymore Field Developments Piper and Claymore Field Developments Piper Platform Construction Piper Platform Construction In June 1975, Occidental began installation of the Piper platform. In water 474 ft deep, at 58.5 deg. N latitude, this platform. In water 474 ft deep, at 58.5 deg. N latitude, this drilling production platform was designed to accommodate a total of 36 wells, with provisions for 30 production wells and 4 water and 2 gas injection wells. Platform production and support facilities were designed for production and support facilities were designed for 250,000 B/D oil production, 330,000 B/D water injection, and 70 MMscf/D gas processing. The platform jacket, constructed in Scotland and weighing about 14,300 tons at launching, was towed to the field in June 1975, launched from the barge Intermac 600, upended, rapidly pinned with four 48-in. pin piles, and driven 110 ft into the seabed through four inner piles, and driven 110 ft into the seabed through four inner legs. Because of poor local soil conditions, the jacket design provided for six 60-in. primary piles per comer, driven to 115 ft, and an insert pile in each primary pile. The inserts were grouted into holes predrilled 380 ft below the mud line and tapered from 50 to 36 in. JPT P. 1679

Offshore Platform Construction Extended To 400-foot Water Depths

LEE, GRIFF C., MEMBER AIME, J. RAY McDERMOTT and CO., INC., NEW ORLEANS, LA. Abstract Platforms have been installed in water depths slightly over 200 ft. At the present time there are over one-quarter of a million acres under lease in water depths greater than 200 ft in the Gulf of Mexico. To develop and produce oil found in these leases, platforms will be required. This paper presents the major problems involved in platform construction and discusses possible methods of installation.Since offshore platform construction began in 1947, over 1,000 platforms have been completed in the Gulf of Mexico. Platforms existing in approximately 200 ft of water have been built by lifting the jacket in place with two derrick barges, by launching the jacket from a cargo barge and by installing buoyant jacket with controlled flotation. These same methods are practical and can be extended to deeper water. Present technology and construction equipment are adequate to build platforms in the 400-ft depth range; however, considerable engineering will be required to plan the best suitable platform for a specific requirement. Introduction Offshore platforms have been installed in open water in depths slightly over 200 ft. The lease sale of March, 1962, awarded 246,700 acres in water depths between 200 and 600 ft. Drilling in the Gulf of Mexico is currently underway from floating vessels in water depths of approximately 300 ft. Even with the recent developments in floating drilling and underwater completion techniques, platforms are necessary for development of offshore oil fields and will remain necessary for the foreseeable future. Platforms provide the safest and most dependable means of drilling offshore wells. Any deep-water oil production found in the Gulf will be located far from shore. Only a large oil field could justify a pipeline to shore. Quarters, production and storage facilities will be required in the field whether the drilling was done from floating vessels or from fixed platforms.The purpose of this paper is to present general problems involved in construction of platforms in deeper water and to discuss possible means of installation. Installation techniques or design procedures will not be discussed in detail. Rather, discussion will be limited to the construction of fixed platforms similar to those currently being installed in the Gulf of Mexico. Historical Background In 1946 the petroleum industry looked longingly at the submerged lands in the Gulf of Mexico which were beyond the reach of drilling from timber trestles and platforms. The beginning of modern platform construction came in 1947 with the installation of the first jacket or template-type platform in approximately 50 ft of water. Eight years later, in 1955, the first platform was installed in water 100-ft deep, and by 1959 this had been extended to 200 ft.During the early days of offshore construction, many types of structures were erected. The first platforms were installed by small equipment and required a long installation time. These were supported by a large number of small piles and required considerable bracing, which offered high resistance to wave action. The designs were based on limited data, since very little information was available on the wave forces of hurricanes. As more information became available, platforms were built stronger and more wave-resistant. Larger construction equipment has been built to allow handling heavier units. Designs and construction techniques have been improved and streamlined to yield the present-day platform which utilizes a few large-diameter piling with a minimum of bracing.After 15 years, over 1,000 platforms have been constructed in the Gulf of Mexico. Only a few structural failures have occurred, and there has been no loss of life due to these failures. Most platforms have been installed in water depths up to 150 ft, but four drilling platforms have been installed in water deeper than 180 ft. In other areas, two platforms were built in similar depths Argus Island, a research platform installed for the U. S. Navy, off Bermuda, and Texas Tower No. 4, a radar station built in the North Atlantic. Platform Requirements A platform designed for deeper water must satisfy the following basic requirements..1. The intended purpose must be fulfilled. JPT P. 383^