Single-Pile Offshore Structures as a Cost-Effective Alternative to Small Fixed Platforms in Shallow Water

2021 ◽  
Author(s):  
Prabir Kumar Chatterjee
Keyword(s):  
Shallow Water ◽  
Design Method ◽  
Cost Effective ◽  
Offshore Structures ◽  
Single Pile ◽  
Offshore Platforms ◽  
Environmental Loads ◽  
Working Stress ◽  
Cost Effective Alternative ◽  
Water Depths

Abstract The present paper proposes an alternative to small offshore platforms with tripods and four-legged jackets by a single-pile structure for shallow water depths. The pile will be driven into seabed without a jacket and stability of the structure against environmental loads will be ensured by a few tie members connected to seabed with the help of specially-designed small concrete foundations. Tie members will be bolted to both the pile and the foundation. Four different cases of single-pile structures in three different water depths (20.0m, 31.5m and 15.0m) are presented. Omnidirectional waves of 10.0m height along with wind and current are considered in the study. Analytical method is suggested to simulate interaction of concrete foundations with soil that can be easily implemented in structural analysis. Structural design is performed as per API RP 2A working stress design method. The results indicate that the proposed single-pile structures have considerable reserve strength against failure due to extreme environmental loads and impact from medium sized boats.

DEEPWATER DRILLING AND PRODUCTION SYSTEMS OVERVIEW

1979 ◽  
Vol 19 (1) ◽  
pp. 166
Author(s):  
J. M. McKinney
Keyword(s):  
Production Systems ◽  
Petroleum Industry ◽  
Sedimentary Basins ◽  
Cost Effective ◽  
Dynamic Positioning System ◽  
Deepwater Drilling ◽  
Attractive Option ◽  
Blowout Preventer ◽  
Cost Effective Alternative ◽  
Water Depths

The petroleum industry is now involved in a highly significant exploration program to define the hydrocarbon potential of deepwater sedimentary basins. Within the last year, the ability to drill in waters deeper than 1300m has been demonstrated, and exploration plans for water depths down to 1600m have been announced. This paper reviews the industry's deepwater drilling experience and describes some of the unique technology required for a successful deepwater drilling venture. Drilling in over 1000m of water calls for more sophisticated, higher strength system components than are needed in shallower waters. Some of the differences between deepwater drilling procedures and more conventional shallow water techniques involve vessel carrying capacity, the use of a dynamic positioning system for staying on location, riser buoyancy materials, improved riser components and a multiplex electrohydraulic blowout preventer control system.Progress has also been made in developing production systems for use in water depths greater than 300m. The guyed tower concept, a product of Exxon's developmental work, has been demonstrated to be a cost-effective alternative to fixed-bottom platforms. The caisson vessel, designed to accommodate both drilling and production activities and to minimize motion caused by rough sea conditions, is an attractive option for operations in deep water. In addition, experience with a prototype of Exxon's subsea production system has demonstrated that this system is also ready for commercial use.

Damping-Controlled Response of a Truss-Pontoon Semi-Submersible With Heave-Plates

2005 ◽  
Author(s):  
Nagan Srinivasan ◽  
Subrata Chakrabarti ◽  
R. Radha
Keyword(s):  
Separated Flow ◽  
Cost Effective ◽  
Added Mass ◽  
Offshore Structures ◽  
Field Application ◽  
Offshore Platform ◽  
Offshore Platforms ◽  
Scaled Model ◽  
Large Wave ◽  
Truss Spar

Hydrodynamic added mass and damping are old and popular research topics in the field of offshore structures engineering. The concept of added mass has been used very intelligently in the design of modern deepwater floating vessels. The turning point of the conventional Spar to a Truss-Spar is a typical example in which the added mass created by the heave plates in a Truss Spar efficiently reduced the steel weight and the subsequent cost of the Spar hull. However, the damping is not utilized as efficiently as the added mass in the design of the floating offshore platforms. It should be noted that at resonance damping plays an important role in controlling the response amplitude. This resonance is called damping controlled response. An offshore platform efficiently designed to reduce the wave excitation forces and increase the separated-flow damping could qualify as a platform to operate even near resonance. Such design could make this concept cost effective, as well as operationally more productive with minimum downtime. The principal purpose of this paper is to describe an offshore platform design that could face the resonance efficiently. The paper applies the concept of both hydrodynamic added mass and separated-flow damping intelligently in the design of a large floating vessel on column-stabilized principle. The platform is designed to face resonance due to extreme waves and utilizes the damping to control its motion, thereby qualifying its field application. The design is verified and justified with the help of a scaled-model study in a large wave tank. The results are presented herein.

scholarly journals The Accuracy of Satellite Derived Bathymetry in Coastal and Shallow Water Zone

2021 ◽  
Vol 8 (3) ◽  
pp. 1-8
Author(s):  
Kelvin Kang Wee Tang ◽  
Mohd Razali Mahmud
Keyword(s):  
Shallow Water ◽  
Sustainable Development Goals ◽  
Cost Effective ◽  
Minimum Standard ◽  
Seafloor Topography ◽  
Minimum Requirement ◽  
Seabed Topography ◽  
Multispectral Satellite Imagery ◽  
Development Goals ◽  
Water Depths

Precise and accurate bathymetric measurements are conventionally acquired by means of ship-based acoustic equipment. Nevertheless, recent multispectral satellite imagery has been utilised as a substitute source to map the seabed topography which indicates new revolution in hydrographic surveying. This study assesses the satellite bathymetric depth’s accuracy based on the vertical uncertainty as stated in the Standards for Hydrographic Surveys issued by the International Hydrographic Organization. Two empirical algorithms, namely, Dierssen’s and Stumpf’s approaches have been adopted to model the seafloor topography over the coastal and shallow water at Tanjung Kupang, Malaysia. The outcomes demonstrate a decent correlation between the derived water depths and the sounding values acquired from a ship-based acoustic survey. For instance, a total of 1,215 out of the 1,367 generated water depths by Stumpf’s model have hit the minimum standard of survey in S-44. Similarly, out of the 1,367 samples from Diessen’s model, 1,211 samples have met the minimum requirement listed in the survey standard. The results demonstrate both imageries derived bathymetry models convey promising results which can be ultilised for bathymetric mapping application. Therefore, this imagery derived bathymetry can be considered as an alternative bathymetric surveying technique to supply cost-effective solution and survey data to support the Blue Economy and Sustainable Development Goals 14.

scholarly journals The Limpet: A ROS-Enabled Multi-Sensing Platform for the ORCA Hub

2018 ◽  
Author(s):  
Mohammed E. Sayed ◽  
Markus P. Nemitz ◽  
Simona Aracri ◽  
Alistair C. McConnell ◽  
Ross M. McKenzie ◽  
...  
Keyword(s):  
Condition Monitoring ◽  
Communication Systems ◽  
Oil And Gas ◽  
Low Cost ◽  
Cost Effective ◽  
Oil And Gas Industry ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Sensor Data ◽  
Offshore Platforms

The oil and gas industry faces increasing pressure to remove people from dangerous offshore environments. Robots present a cost-effective and safe method for inspection, repair and maintenance of topside and marine offshore infrastructure. In this work, we introduce a new immobile multi-sensing robot, the Limpet, which is designed to be low-cost and highly manufacturable, and thus can be deployed in huge collectives for monitoring offshore platforms. The Limpet can be considered an instrument, where in abstract terms, an instrument is a device that transforms a physical variable of interest (measurand) into a form that is suitable for recording (measurement). The Limpet is designed to be part of the ORCA (Offshore Robotics for Certification of Assets) Hub System, which consists of the offshore assets and all the robots (UAVs, drones, mobile legged robots etc.) interacting with them. The Limpet comprises the sensing aspect of the ORCA Hub System. We integrated the Limpet with Robot Operating System (ROS), which allows it to interact with other robots in the ORCA Hub System. In this work, we demonstrate how the Limpet can be used to achieve real-time condition monitoring for offshore structures, by combining remote sensing with signal processing techniques. We show an example of this approach for monitoring offshore wind turbines. We demonstrate the use of four different communication systems (WiFi, serial, LoRa and optical communication) for the condition monitoring process. By processing the sensor data on-board, we reduce the information density of our transmissions, which allows us to substitute short-range high-bandwidth communication systems with low-bandwidth long-range communication systems. We train our classifier offline and transfer its parameters to the Limpet for online classification, where it makes an autonomous decision based on the condition of the monitored structure.

Finite Element Analysis for Structural Performance of Offshore Platforms under Environmental Loads

2013 ◽  
Vol 569-570 ◽  
pp. 159-166 ◽  
Author(s):  
Shehata E. Abdel Raheem ◽  
Elsayed M.A. Abdel Aal
Keyword(s):  
Finite Element ◽  
Return Period ◽  
Wave Force ◽  
Offshore Structures ◽  
Offshore Platform ◽  
Offshore Platforms ◽  
Offshore Structure ◽  
Current Increase ◽  
Environmental Loads ◽  
Highly Nonlinear

Offshore structures for oil and gas exploitation are subjected to various ocean environmental phenomena which can cause highly nonlinear action effects. Offshore structures should be designed for severe environmental loads and strict requirements should set for the optimum performance. The structural design requirements of an offshore platform subjected to wave induced forces and moments in the jacket can play a major role in the design of the offshore structures. For an economic and reliable design; good estimation of wave loadings are essential. The structure is discretized using the finite element method, wave force is determined according to linearized Morison equation. Hydrodynamic loading on horizontal and vertical tubular members and the dynamic response of fixed offshore structure together with the distribution of displacement, axial force and bending moment along the leg are investigated for regular and extreme conditions, where the structure should keep production capability in conditions of the one year return period wave and must be able to survive the 100 year return period storm conditions. The results show that the nonlinear response analysis is quite crucial for safe design and operation of offshore platform. Fixed Jacket type offshore platforms under extreme wave loading conditions may exhibit significant nonlinear behavior. The effect of current with different angles when hitting the offshore structure with the wave and wind forces, is very important for calculate the stress, the response displacement and deformation shapes. As the current increase or decrease the effect of wave force according to the hitting angle of current.

Niobium-Bearing Offshore Plate Steel Process Metallurgy, Design and Quality

2016 ◽  
Author(s):  
Steven G. Jansto
Keyword(s):  
Corrosion Resistance ◽  
High Performance ◽  
Cost Savings ◽  
Value Added ◽  
Cost Effective ◽  
Offshore Structures ◽  
Offshore Platforms ◽  
Low Carbon ◽  
Steel Mill ◽  
Excellent Corrosion Resistance

Offshore structural steel design and material requirements continue to present increasing challenges for the steelmaker and fabricators. Niobium-bearing steels currently play a key role in meeting these objectives through the Nb-grain refinement mechanism of the microstructure and cost effective steelmaking. These steels possess a combination of exceptional properties with high strength, excellent weldability, high toughness at low temperature, good ductility, excellent corrosion resistance, and high formability. Reduced variation of Charpy toughness through the thickness of heavy plates is imperative in these offshore platforms to enhance reliability and performance. Toughness variation can be reduced through the proper continuous casting and hot rolling mechanical metallurgy process. These high-performance steels (HPS) possess an optimized balance of these properties to provide maximum cost effective performance in offshore structures at strength levels from 355 to 700MPa with excellent corrosion resistance. This combination of good strength-toughness balance, excellent weathering properties and reduced preheat temperatures for welding in these low carbon Nb-structural steels result in significant cost savings. These enhancements provide structural engineers the opportunity to further improve the structural design and offshore platform performance. Lower carbon Nb-alloy designs have exhibited reduced operational production cost at the steel mill as well, thereby embracing the value-added attribute Nb provides to benefit both the producer and the end user throughout the supply chain.

2D Color-Intensity Representation of Ultrasonic Thickness Gauge Measurements

2020 ◽  
pp. 1192-1198
Author(s):  
M.S. Mohammad ◽  
Tibebe Tesfaye ◽  
Kim Ki-Seong
Keyword(s):  
Cost Effective ◽  
The Other ◽  
Thickness Gauge ◽  
Color Intensity ◽  
Digital Readout ◽  
Flat Surfaces ◽  
Video Cameras ◽  
Wide Range ◽  
Cost Effective Alternative ◽  
Ultrasonic Thickness

Ultrasonic thickness gauges are easy to operate and reliable, and can be used to measure a wide range of thicknesses and inspect all engineering materials. Supplementing the simple ultrasonic thickness gauges that present results in either a digital readout or as an A-scan with systems that enable correlating the measured values to their positions on the inspected surface to produce a two-dimensional (2D) thickness representation can extend their benefits and provide a cost-effective alternative to expensive advanced C-scan machines. In previous work, the authors introduced a system for the positioning and mapping of the values measured by the ultrasonic thickness gauges and flaw detectors (Tesfaye et al. 2019). The system is an alternative to the systems that use mechanical scanners, encoders, and sophisticated UT machines. It used a camera to record the probe’s movement and a projected laser grid obtained by a laser pattern generator to locate the probe on the inspected surface. In this paper, a novel system is proposed to be applied to flat surfaces, in addition to overcoming the other limitations posed due to the use of the laser projection. The proposed system uses two video cameras, one to monitor the probe’s movement on the inspected surface and the other to capture the corresponding digital readout of the thickness gauge. The acquired images of the probe’s position and thickness gauge readout are processed to plot the measured data in a 2D color-coded map. The system is meant to be simpler and more effective than the previous development.

A method of technical diagnostics for offshore structures

1994 ◽  
Vol 16 (2) ◽  
pp. 43-48
Author(s):  
Do Son
Keyword(s):  
Diagnostic Method ◽  
Joint Venture ◽  
Oil And Gas ◽  
Residual Life ◽  
Life Time ◽  
Offshore Structures ◽  
Technical Diagnostics ◽  
Offshore Platforms ◽  
South Vietnam ◽  
Local Destruction

This paper describes the results of measurements and analysis of the parameters, characterizing technical state of offshore platforms in Vietnam Sea. Based on decreasing in time material characteristics because of corrosion and local destruction assessment on residual life time of platforms is given and variants for its repair are recommended. The results allowed to confirm advantage of proposed technical diagnostic method in comparison with others and have been used for oil and gas platform of Joint Venture "Vietsovpetro" in South Vietnam.

JS777

Alloy Digest ◽  
1980 ◽  
Vol 29 (11) ◽  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Austenitic Stainless Steel ◽  
Cost Effective ◽  
Heat Treating ◽  
Steel Company ◽  
High Alloy ◽  
Cost Effective Alternative ◽  
Resistance To Stress ◽  
Nickel Base

Abstract JS777 is a high-alloy, fully austenitic stainless steel developed for applications where corrosive conditions are too severe for the standard grades of stainless steel. It also provides a cost-effective alternative to more expensive nickel-base and titanium-base alloys. It has relatively high resistance to stress-corrosion cracking and to intergranular corrosion. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: SS-377. Producer or source: Jessop Steel Company.

ANCORSTEEL 4300

Alloy Digest ◽  
2009 ◽  
Vol 58 (11) ◽  
Keyword(s):  
Fracture Toughness ◽  
Physical Properties ◽  
Tensile Properties ◽  
Cost Effective ◽  
Heat Treating ◽  
Effective Alternative ◽  
Powder Metal ◽  
Secondary Processing ◽  
Cost Effective Alternative

Abstract Ancorsteel 4300 alloy ferrous powder simulates wrought steel compositions and is a cost-effective alternative to alloys requiring secondary processing. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness. It also includes information on heat treating and powder metal forms. Filing Code: SA-611. Producer or source: Hoeganaes Corporation.

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