The Tension Leg Semisubmersible (TLS): The Hybrid TLP-Semisubmersible Floater With the Spar Response

Mansour, Alaa; Wu, Chunfa; Kumar, Dhiraj; Zuccolo, Ricardo

doi:10.1115/omae2014-23533

Cited by 4 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The conical shaped columns provide varying water plane area to prevent/cancel out parametric coupling between heave and pitch/roll motions. [17], [18] In summary, the variations in topsides, hull, and mooring system among Theme C1 concepts are as follows: Topside integration for the GoM design case with deeper draft is obtained through floatover in sheltered water.…”

Section: Group I -Semi-sub Shaped Hull Designs Dt Operationsmentioning

confidence: 99%

Alternative Direct Vertical Access Solutions for Development of Marginal Assets in Deepwater - a DeepStar Study

et al. 2015

View full text Add to dashboard Cite

This paper is based on a DeepStar study undertaken to evaluate innovative deepwater floating platforms and riser systems, with dry tree (DT) or direct vertical access (DVA) capability, for development of marginal fields and benchmarking with proven dry tree platform concepts [1][2][3]. The spread moored semi-sub shaped and hybrid novel hull designs with top tension risers (TTRs) and quayside integration of topsides overcome key concerns with both TLP and Truss Spar with TTRs and provide cost effective solutions for ultra-deepwater marginal fields.The designs were developed for three regions (Gulf of Mexico, West of Africa, and Offshore Western Australia) and three water depths (3,000 ft, 6,000 ft, and 8,000 ft) for a common design basis with defined topsides and riser payloads, and specified design constraints. The estimates for novel designs were obtained from eight Concept Owners, and a comparative assessment was performed for 13 designs in three groups for nine combinations of regions and water depths. Coupled analysis was performed for most novel designs for GoM 6,000 and WoA 6,000.The five field development themes with DT benchmarks, novel hull, novel riser, drilling or process will be described. The key design, global performance, and constructability features of alternative concepts will be discussed. The variability in key estimates for three groups will be identified. The novel hull designs evaluated enable integration of topsides at quayside or by floatover and provide ability to support DTs and long stroke RAM tensioners. For designs evaluated with a modular drilling rig and upto six TTRs, lower CAPEX is estimated.The ranges of key design data, tensioner stroke, and global performance for each group have distinct variations. The novel riser design considered is Compliant Vertical Access Riser (CVAR), which is an offset riser with no tensioners, thus it enables use of semi-sub design with lesser draft. The development themes with wet trees and a drilling riser reduce the payload on hull.Technology readiness level (TRL) varies for the novel concepts. The detailed comparative assessment undertaken showed high potential for standardization of hull designs. In ultra-deepwater regions with harsh metocean conditions, several of these novel hull designs provide enabling solutions. This is the first major effort undertaken with evaluation of 13 alternative design cases with DT or DVA capability. The evaluations done for three regions would also be applicable in many other regions. The documentation of estimates in three groups identifies benefits from novel designs over benchmarks designs in each group, and distinct variations among groups. These results would help in selection of specific concepts for a region for further qualification and project readiness for development of worldwide marginal deepwater and ultra-deepwater fields.

show abstract

Section: Group I -Semi-sub Shaped Hull Designs Dt Operationsmentioning

confidence: 99%

Alternative Direct Vertical Access Solutions for Development of Marginal Assets in Deepwater - a DeepStar Study

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Examples of this effort are documented in [2,5,[7][8][9][10][11][12][13][14]16,17]. Examples of this effort are documented in [2,5,[7][8][9][10][11][12][13][14]16,17].…”

Section: Introductionmentioning

confidence: 99%

“…Most of the dry-tree semi-submersibles proposed utilize one or more of these design features [7][8][9][11][12][13][14]. Other means are increasing the number of columns and optimizing the hull shape.…”

Section: Introductionmentioning

confidence: 99%

Low-Heave Semi-Submersible Enabling Dry-Tree Field Development

Muehlner¹,

Banumurthy²

2015

All Days

View full text Add to dashboard Cite

The objective of this paper is to present the new Offset-Pontoon Semi-submersible (OPS) for use as a drilling and production platform. The new semi-submersible features pontoons that are offset to the outside of the columns which lends the vessel a low heave response and enables the use of top tension risers with dry trees. Other advantages of the OPS are a shallow quayside draft, a large payload capacity and the ability to operate in ultra-deepwater.The primary design challenge for dry-tree semi-submersibles is to make their heave motions compatible with the stroke range of existing riser tensioners. Increasing the vessel draft to reduce the heave motions is constrained by installation requirements and stability limits. However, vessel heave motions can be reduced by modifying the hull shape.The OPS has a longer heave natural period and a smaller heave response than a conventional deep-draft semi-submersible. The heave performance of the OPS was compared with a conventional semisubmersible using frequency-and time-domain analyses.In this paper we also present a design study of the OPS for dry-tree field development offshore Brazil. The vessel was sized to support thirteen top-tension risers and a 30,000 ton topside. The paper describes design of the vessel and its global performance. Focus of the study was the wellbay loayout and the tensioner stroke requirements. For the selected design case we found ram-style riser tensioners with a stroke range of 30 ft sufficient. Integration of the hull and topside by float-over is also described.

show abstract

Semisubmersibles

Mansour

Greiner

et al. 2017

Encyclopedia of Maritime and Offshore Engineering

View full text Add to dashboard Cite

Semisubmersible platforms are one of the widely used floaters in the offshore and marine industry. They can support the operating topside well above the mean sea level through a number of vertical columns. They gain their buoyancy mainly from pontoon structures at the lower end of the columns well below the water surface. Columns also contribute to the buoyancy of the platform. Semisubmersible platforms are recognized for their high stability provided by widely separated columns and their buoyant cross‐sectional area. This high stability enables semisubmersible floaters to support topsides at high elevations away from direct wave impact. Compared to ship‐shaped floaters, semisubmersibles offer much lower motion response in harsh wave environments. The improved response is driven by the longer system natural periods and the lower hydrodynamic loads on the pontoon due to their position deep below the water surface away from the wave action. In this article, a description of the semisubmersibles and their key applications as related to the offshore and marine fields are presented. This article also provides an overview of the fabrication, transportation, and installation operations of semisubmersibles. Elaborations on the design considerations of semisubmersibles including hull sizing, stability, weight control, global performance, hull structure, and hull system are included. Overview of the riser systems that can be hosted on semisubmersible is also presented. This article concludes with a high level summary of the new trend and next‐generation semisubmersibles.

show abstract

The Tension Leg Semisubmersible (TLS): The Hybrid TLP-Semisubmersible Floater With the Spar Response

Cited by 4 publications

References 0 publications

Alternative Direct Vertical Access Solutions for Development of Marginal Assets in Deepwater - a DeepStar Study

Alternative Direct Vertical Access Solutions for Development of Marginal Assets in Deepwater - a DeepStar Study

Low-Heave Semi-Submersible Enabling Dry-Tree Field Development

Semisubmersibles

Contact Info

Product

Resources

About