A Comparison of Radial Wellbay and Traditional Truss Spar Designs

2011 ◽  
Author(s):  
John Murray ◽  
Edmund Muehlner ◽  
Guibog Choi
Keyword(s):  
Gulf Of Mexico ◽  
Deep Water ◽  
Performance Comparison ◽  
The Arctic ◽  
Base Case ◽  
Mooring Lines ◽  
Production Platform ◽  
Truss Spar ◽  
Motion Performance ◽  
Made In

The Spar continues to be a popular drilling and production platform design for ultra-deep water. In recent years, developers have introduced a number of design variations such as the Arctic Spar, closed centerwell Spar, and long Spar. As the industry moves production into ultra-deep water, the escalation in drilling costs, particularly for deeper more complicated wells, prompts the need to look for new deepwater floater designs, including Spars. This paper introduces some new features to the Truss Spar, including a radial wellbay layout and an adjustable buoyancy centerwell device. This new Radial Wellbay Spar design is investigated and compared to the traditional Truss Spar for the same topside and riser weights and subjected to the same environments. The base case assumes a drilling and production platform with the performance comparison made in terms of hull weights and dimensions and hull motions for post-Katrina Gulf of Mexico conditions. In general, the Radial Wellbay Spar offers a smaller hull with fewer mooring lines for the same payload while maintaining the Spar’s low motion performance.

The Effect of Mooring System and Sheared Currents on Vortex Induced Motions of Truss Spars

2003 ◽  
Author(s):  
Radboud R. T. van Dijk ◽  
Arjan Voogt ◽  
Paul Fourchy ◽  
Saadat Mirza
Keyword(s):  
Gulf Of Mexico ◽  
Mooring System ◽  
Test Results ◽  
Current Profile ◽  
Scaled Model ◽  
Production Platform ◽  
Helical Strakes ◽  
Truss Spar ◽  
Set Up ◽  
Program Show

Since 1996 Spars have been used as production platform in the Gulf of Mexico. Spar Vortex Induced Motions (VIM) in strong currents like the hurricane and loop currents are an important consideration for the design of the mooring system and risers. This is important for the extreme offsets as well as fatigue in risers and the mooring system. This paper compares the VIM behavior of a truss Spar in sheared currents, like the Hurricane current in the Gulf of Mexico, with tow test results. Experiments have been carried out on a scaled model in both a complete mooring system and in a towing set-up with a simplified horizontal mooring. The Spar model consists of a hard tank with removable helical strakes, a truss section and a square soft tank. The results of this model test program show that both the choice of the mooring system and current profile have a significant influence on the VIM response of the Spar. The paper discusses the results of this research and also addresses important issues and considerations for VIM model tests.

Self-Installed Single Column Floater

2004 ◽  
Author(s):  
Frank Chou ◽  
John Chianis ◽  
Xinyu Zhang
Keyword(s):  
Gulf Of Mexico ◽  
Research And Development ◽  
Deep Water ◽  
Oil And Gas ◽  
Geographical Area ◽  
Current Concept ◽  
Motion Responses ◽  
Production Platform ◽  
Single Column ◽  
Exploration And Production

This paper introduces a novel floating production platform concept for exploration and production of oil and gas in ultra deep water. The developmental effort has been supported by ABB in-house research and development budget. This novel production unit is an enhanced version of ABB Self-Installed Single Column Floater (SISCF) concept. This unit is envisioned to be completely assembled at quayside, towed to location, and be installed vertically to its target draft without the need of a major crane vessel. This enhanced feature reduces the wind load on the deck and hull significantly during wet tow as well as alleviates the uncertainty on the duration of an offshore operation, thereby widens the weather window for installation, hook-up and commissioning offshore. The enhanced SISCF (ESISCF) hull consists of four major components i.e., hard tank with center opening, soft tank with telescoping truss members and opening, permanent-stability ring, and three (3) telescoping support columns. During the installation phase, the telescoping columns are used to guide the permanent-stability ring, which provided needed stability in the installation phase. In addition, because of the way center truss being constructed, the hard tank is collapsed (or sit) right on top of the soft tank during wet tow thus reduced the wind arm (almost 100 ft) and wind forces. In its in-place position, ESISCF motion responses in waves are found to be excellent because of its deep draft. The current concept combines the advantages of a spar and a semi-submersible vessel. The paper will detail the concept, and outline the fabrication to installation scenario. The principal dimensions of a typical ESISCF for a given payload will be presented together with its stability and motion responses in waves based on the sea conditions representing a typical geographical area of Gulf of Mexico. The advantages of this concept will be explained in detail.

Innovative Concept of a Drilling and/or Production Platform for Operating in Arctic and Deep Water

2007 ◽  
Author(s):  
Frank Chou ◽  
Susobhan Ghosh ◽  
Kevin Huang
Keyword(s):  
Deep Water ◽  
Winter Season ◽  
Arctic Region ◽  
Mooring System ◽  
Floating Platform ◽  
Mooring Lines ◽  
Arctic Condition ◽  
Strong Current ◽  
Production Platform ◽  
Conical Structure

A concept of an innovative floating platform using a conical structure was originally developed for operation in arctic region. It is called as MCAD (MonoCone Arctic Drilling Platform). The conical structure is used to reduce ice-loading as it facilitates ice to break in flexure while riding the slope of the conical surface. For supporting the weight of the platform, equipment, and ballast, a base structure with sufficient buoyancy is added at the base of conical structure. To ensure the platform with adequate stability, a heavy (solid) ballasting system that can be lowered to adjust the vertical center of gravity of the platform is incorporated in the system. The conceptual platform configuration has been analyzed for a large payload of more than 25,000 ST operating in approximately 125 feet of water depth. In the winter season, the platform is subjected to more than 12,000 ST of ice load. For warmer season the platform has been designed to survive a 45 feet significant wave height with 80 knots wind, and a very strong current of 6 knots. To withstand such magnitude of ice forces, mooring system using 32 lines was designed. For lower ice loads in a milder environment, the number of mooring lines can be reduced considerably. For operating in the warmer season, the platform was analyzed for design environments of operating and survival conditions. The motion responses in these conditions were found to be excellent in comparison to other deepwater concepts in use. With the promising motion response results of the conceptual platform with such a high payload, the concept is expected to provide operating company an alternative for deepwater application as well. Since the concept has been developed for a very large payload, the excess payload may be utilized as storages of produced oil. Mooring system for operating in deep water has been developed, and has been compared with that of the system for arctic condition. This paper describes the concept identifying the salient features. The effects of various features on the design and platform performance are also described. The ballast system with its lowering system makes this concept attractive for easy installation without the assistance of a large derrick vessel, a significant reduction of installation time is also expected. Results of stability, motion and mooring analyses is presented in the paper as well. Preliminary structural analyses were carried out to confirm the viability of the concept in operational, installation and survival conditions.

Sirena Dotada truss spar design for East Central Gulf of Mexico

OCEANS 2009 ◽  
2009 ◽  
Author(s):  
C. Dunbar ◽  
J. Cotten ◽  
R. Hartsfield ◽  
D. Garcia ◽  
R. Vallejo
Keyword(s):  
Gulf Of Mexico ◽  
East Central ◽  
Truss Spar

The Reproductive Biology of Ophiacantha Bidentata (Echinodermata: Ophiuroidea) From The Rockall Trough

1982 ◽  
Vol 62 (1) ◽  
pp. 45-55 ◽  
Author(s):  
P. A. Tyler ◽  
J. D. Gage
Keyword(s):  
Reproductive Biology ◽  
Deep Water ◽  
Larval Stage ◽  
North Pacific ◽  
Deep Sea ◽  
Direct Development ◽  
The Arctic ◽  
Shallow Waters ◽  
Arctic Seas ◽  
Rockall Trough

INTRODUCTIONOphiacantha bidentata (Retzius) is a widespread arctic-boreal ophiuroid with a circumpolar distribution in the shallow waters of the Arctic seas and penetrating into the deep sea of the.North Atlantic and North Pacific (Mortensen, 1927, 1933a; D'yakonov, 1954). Early observations of this species were confined to defining zoogeo-graphical and taxonomic criteria including the separation of deep water specimens as the variety fraterna (Farran, 1912; Grieg, 1921; Mortensen, 1933a). Mortensen (1910) and Thorson (1936, pp. 18–26) noted the large eggs (o.8 mm diameter) in specimens from Greenland and Thorson (1936) proposed that this species had ‘big eggs rich in yolk, shed directly into the sea. Much reduced larval stage or direct development’. This evidence is supported by observations of O. bidentata from the White and Barents Seas (Semenova, Mileikovsky & Nesis, 1964; Kaufman, 1974)..

scholarly journals Impact of the Deepwater Horizon oil spill on a deep-water coral community in the Gulf of Mexico

2012 ◽  
Vol 109 (50) ◽  
pp. 20303-20308 ◽  
Author(s):  
H. K. White ◽  
P.-Y. Hsing ◽  
W. Cho ◽  
T. M. Shank ◽  
E. E. Cordes ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Oil Spill ◽  
Deep Water ◽  
Deepwater Horizon ◽  
Coral Community ◽  
Deepwater Horizon Oil Spill ◽  
Water Coral

Modeling Dynamic Shock Loads for High-Pressure/Deep-Water Tubing-Conveyed Perforating Operations in the Gulf of Mexico

2012 ◽  
Author(s):  
Rick L. Giunta ◽  
Cam Van Le ◽  
Martin F. Schoener-Scott ◽  
Ryan Neal Anderson ◽  
Joshua Monroe Glass
Keyword(s):  
High Pressure ◽  
Gulf Of Mexico ◽  
Deep Water ◽  
Shock Loads

Development of a Stepped Line Tensioning Solution for Mitigating VIM Effects in Loop Eddy Currents for the Genesis Spar

2004 ◽  
Author(s):  
T. Kokkinis ◽  
R. E. Sandstro¨m ◽  
H. T. Jones ◽  
H. M. Thompson ◽  
W. L. Greiner
Keyword(s):  
Gulf Of Mexico ◽  
Eddy Current ◽  
Eddy Currents ◽  
Comprehensive Evaluation ◽  
Design Solution ◽  
Loop Current ◽  
Mooring Lines ◽  
Test Methodology ◽  
Induced Motion ◽  
High Reynolds

A number of spars are being installed in deepwater areas in the Gulf of Mexico (GoM), which are subject to loop / eddy current conditions and must be designed for Vortex-Induced Motion (VIM). This paper shows how recent advances in VIM prediction enabled an efficient and effective mooring design solution for the existing Genesis classic spar, which is installed in Green Canyon Block 205 in the GOM. The solution may also be applicable to new spar designs. During the Gulf of Mexico Millennium Eddy Current event in April 2001, the Genesis spar platform underwent vortex induced motions (VIM) which were greater than anticipated during the design of the mooring & riser systems. Analysis showed that if such large motions were to occur in higher currents in the range of the 100-year event, they could cause significant fatigue damage, and could lead to peak tensions in excess of design allowables. After a comprehensive evaluation of potential solutions, Stepped Line Tensioning (SLT) was determined to be the best approach for restoring the platform’s original mooring capacity on technical, cost and schedule grounds. SLT did not require extensive redesign of the existing mooring system of the spar. Furthermore, SLT provided a means to improve mooring integrity on an interim basis, while completing details for permanent implementation. Under SLT, the pretensions of the mooring lines are adjusted based on forecast currents in order to keep the platform below the VIM lock-in threshold at all times and for all eddy/loop current conditions up to and including the 100-year condition. High Reynolds number model tests conducted with a new test methodology were used to get a reliable prediction of the spar’s VIM response for this evaluation.

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