FourStar™ Dry-Tree Semisubmersible Development

2010 ◽  
Author(s):  
Neil Williams ◽  
Steve Leverette ◽  
Sean Bian ◽  
Sean Large ◽  
Peimin Cao
Keyword(s):  
Water Depth ◽  
Model Tests ◽  
Wave Basin

This paper discusses the development of a dry-tree semisubmersible (DTS) platform concept appropriate for deployment in non-hurricane/non-cyclonic environments worldwide, and the verification of the concept through wave basin model tests. An example configuration is presented for an application in 2,100 m water depth offshore Brazil.

Experimental Determination of Resonant Response in the Narrow Gap Between Two Side-by-Side Fixed Bodies in Deep Water

2016 ◽  
Author(s):  
Wenhua Zhao ◽  
Hugh Wolgamot ◽  
Scott Draper ◽  
Paul H. Taylor ◽  
Rodney Eatock Taylor ◽  
...  
Keyword(s):  
White Noise ◽  
Numerical Simulations ◽  
Water Depth ◽  
Deep Water ◽  
Model Tests ◽  
Full Scale ◽  
Resonance Phenomenon ◽  
Resonant Response ◽  
Gap Resonance ◽  
Wave Basin

Floating liquefied natural gas (FLNG) facilities are a new type of offshore structure, which have been developed as a game changer in offshore hydrocarbon development for unlocking stranded gas reserves. One of the key challenges associated is offloading from FLNG facilities to LNG carriers. Offloading may proceed with vessels in a side-by-side configuration, which allows offtake by un-modified vessels and minimizes requirements for new hardware or procedures (e.g. compared to a tandem operation). Significant challenges remain, however, and reliable offloading is critical for successful FLNG implementation. In this scenario, the two vessels are separated by a narrow 4 m wide gap. The resonant response of the sea surface in the gap has been predicted by numerical simulations [1] to be a few times that of the incident waves at particular frequencies. As a consequence, the gap resonant response may play a role in determining the operational window for side-by-side offloading operations, and thus has attracted a lot of attention recently. There have been studies on this topic both numerically and experimentally. However, many of these studies are in 2 dimensions (2D), for relatively large gaps and relatively shallow water depth, which may pose difficulties when extending the results to a real project. It is unclear what will happen for a gap resonance if the gap width gets narrower (say 4 m in full scale) and the water depth gets deeper (say 600 m in full scale). In this study, we conducted a series of model tests at a scale of 1:60 in a large wave basin, and focused on deep water and, crucially, narrow gaps, which are closer to a real project geometry. To facilitate future numerical simulations, we used two identical fixed bodies in the model tests and the vessels were simple barge-like shapes. Using white noise waves as the excitation, which covers a broad brand, the response of the fluid in the gap has been measured at several points. In these experiments, different modes of the gap resonance have been observed. Response amplitude operators (RAOs) of the gap resonance have been obtained through spectral analyses, which provide valuable information for the design of side-by-side operations and will benefit future numerical simulations. Test runs in white noise waves with different significant wave heights were also performed, to study the nonlinearities of the gap resonance phenomenon.

Experimental and Numerical Study on Large Truncation of Deepwater Mooring Line

2009 ◽  
Author(s):  
Yihua Su ◽  
Jianmin Yang ◽  
Longfei Xiao ◽  
Gang Chen
Keyword(s):  
Dynamic Response ◽  
Water Depth ◽  
Numerical Study ◽  
Unit Length ◽  
Low Frequency ◽  
Model Tests ◽  
Mooring Line ◽  
Mooring System ◽  
Mooring Lines ◽  
Wave Basin

Modeling the deepwater mooring system in present available basin using standard Froude scaling at an acceptable scale presents new challenges. A prospective method is to truncate the full-depth mooring lines and find an equivalent truncated mooring system that can reproduce both static and dynamic response of the full-depth mooring system, but large truncation arise if the water depth where the deepwater platform located is very deep or the available water depth of the basin is shallow. A Cell-Truss Spar operated in 1500m water depth is calibrated in a wave basin with 4m water depth. Large truncation arises even though a small model scale 1:100 is chosen. A series of truncated mooring lines are designed and investigated through numerical simulations, single line model tests and coupled wave basin model tests. It is found that dynamic response of the truncated mooring line can be enlarged by using larger diameter and mass per unit length in air. Although the truncated mooring line with clump presents a “taut” shape, its dynamic characteristics is dominated by the geometry stiffness and it underestimates dynamic response of the full-depth mooring line, even induces high-frequency dynamic response. There are still two obstacles in realizing dynamic similarity for the largely truncated mooring system: lower mean value of the top tension of upstream mooring lines, and smaller low-frequency mooring-induced damping.

Analysis of Catenary Mooring Systems Based on Truncated Mooring Experiments

2018 ◽  
Author(s):  
Sheng Xu ◽  
Chunyan Ji ◽  
C. Guedes Soares
Keyword(s):  
Water Depth ◽  
Model Tests ◽  
Mooring System ◽  
Coupled Dynamic Analysis ◽  
Motion Responses ◽  
Wave Basin ◽  
Six Dof ◽  
Floating Systems ◽  
Fully Coupled ◽  
Reasonable Model

Considering the activities of floating systems pushing to the ultra-deepwater, the full scale mooring system needs to be truncated in order to carry out model tests in wave basin with reasonable model scale. In this paper, a Semi-Submersible moored by a catenary mooring system, which operates in 1500m water depth is truncated at 200m water depth. The mooring induced damping of truncated mooring system and prototype mooring system in 100 year typhoon condition in South China Sea are studied experimentally and numerically. The de-couple technique is applied to obtain truncated mooring damping, which is implemented by inputting the vessel six DOF motion responses and solving the mooring tensions, then decompose mooring tension in x, y and z directions. The vessel six DOF motion responses were measured in the model tests. For the full depth mooring system, the fully coupled dynamic analysis is carried out to study mooring induced damping. The results of truncated mooring damping will be compared with full depth mooring damping.

Resistance Tests of an Articulated Pusher Barge System in Deep and Shallow Water

2021 ◽  
Author(s):  
Li Zhang ◽  
Lei Xing ◽  
Mingyu Dong ◽  
Weimin Chen
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Deep Water ◽  
Water Resistance ◽  
Model Tests ◽  
System 2 ◽  
Changing Trend ◽  
The Difference ◽  
Transport Vessel ◽  
Resistance Performance

Abstract Articulated pusher barge vessel is a short-distance transport vessel with good economic performance and practicability, which is widely used in the Yangtze River of China. In this present work, the resistance performance of articulated pusher barge vessel in deep water and shallow water was studied by model tests in the towing tank and basin of Shanghai Ship and Shipping Research Institute. During the experimental investigation, the articulated pusher barge vessel was divided into three parts: the pusher, the barge and the articulated pusher barge system. Firstly, the deep water resistance performance of the articulated pusher barge system, barge and the pusher at design draught T was studied, then the water depth h was adjusted, and the shallow water resistance at h/T = 2.0, 1.5 and 1.2 was tested and studied respectively, and the difference between deep water resistance and shallow water resistance at design draught were compared. The results of model tests and analysis show that: 1) in the study of deep water resistance, the total resistance of the barge was larger than that of the articulated pusher barge system. 2) for the barge, the shallow water resistance increases about 0.4–0.7 times at h/T = 2.0, 0.5–1.1 times at h/T = 1.5, and 0.7–2.3 times at h/T = 1.2. 3) for the pusher, the shallow water resistance increases about 1.0–0.4 times at h/T = 2.7, 1.2–0.9 times at h/T = 2.0, and 1.7–2.4 times at h/T = 1.6. 4) for the articulated pusher barge system, the shallow water resistance increases about 0.2–0.3 times at h/T = 2.0, 0.5–1.3 times at h/T = 1.5, and 1.0–3.5 times at h/T = 1.2. Furthermore, the water depth Froude number Frh in shallow water was compared with the changing trend of resistance in shallow water.

Development of Deep Water Multicolumn Buoy

2014 ◽  
Author(s):  
Rodrigo A. Barreira ◽  
Vinicius L. Vileti ◽  
Joel S. Sales ◽  
Sergio H. Sphaier ◽  
Paulo de Tarso T. Esperança
Keyword(s):  
Conceptual Design ◽  
Water Depth ◽  
Deep Water ◽  
Model Tests ◽  
Optimization Process ◽  
Life Duration

A new conceptual design of a deepwater MONOBUOY, named DeepWater MultiColumn Buoy (DWMCB), patent PCT/BR2011/000133, was developed by PETROBRAS/CENPES. The DWMCB was designed to be part of an offloading system for a Spread Moored Floating Production Offloading Unit (FPSO). The offloading system principle consists of Oil being exported from the FPSO to a Shutle tanker passing through Offloading Oil Lines (OOLs) that are supported by the DWMCB. The system is designed to operate at a water depth of 2,200 meters, with expected in site life duration of 25 years. The geometry of DWMCB was defined after an optimization process in order to minimize its motions. This paper describes the development of this concept and discusses the results from some design verifications done with the help of a model tests campaign. An equivalent traditional shaped monobuoy was also tested for comparison purposes.

FPSO response and water depth: A study using model tests

2016 ◽  
pp. 51-54
Author(s):  
V Kurian ◽  
N Rini ◽  
M Liew ◽  
A Whyte
Keyword(s):  
Water Depth ◽  
Model Tests

Experimental Assessment of the Performance of CECO Wave Energy Converter in Irregular Waves

2018 ◽  
Author(s):  
Claudio A. Rodríguez ◽  
F. Taveira-Pinto ◽  
P. Rosa-Santos
Keyword(s):  
Wave Energy ◽  
Transfer Functions ◽  
Nonlinear Effects ◽  
Model Tests ◽  
Experimental Results ◽  
Irregular Waves ◽  
Scale Model ◽  
Experimental Assessment ◽  
Simplified Approach ◽  
Wave Basin

A new concept of wave energy device (CECO) has been proposed and developed at the Hydraulics, Water Resources and Environment Division of the Faculty of Engineering of the University of Porto (FEUP). In a first stage, the proof of concept was performed through physical model tests at the wave basin (Rosa-Santos et al., 2015). These experimental results demonstrated the feasibility of the concept to harness wave energy and provided a preliminary assessment of its performance. Later, an extensive experimental campaign was conducted with an enhanced 1:20 scale model of CECO under regular and irregular long and short-crested waves (Marinheiro et al., 2015). An electric PTO system with adjustable damping levels was also installed on CECO as a mechanism of quantification of the WEC power. The results of regular waves tests have been used to validate a numerical model to gain insight into different potential configurations of CECO and its performance (López et al., 2017a,b). This paper presents the results and analyses of the model tests in irregular waves. A simplified approach based on spectral analyses of the WEC motions is presented as a means of experimental assessment of the damping level of the PTO mechanism and its effect on the WEC power absorption. Transfer functions are also computed to identify nonlinear effects associated to higher waves and to characterize the range of periods where wave absorption is maximized. Furthermore, based on the comparison of the present experimental results with those corresponding to a linear numerical potential model, some discussions are addressed regarding viscous and other nonlinear effects on CECO performance.

FPSO response and water depth: A study using model tests

2016 ◽  
pp. 51-54
Author(s):  
V.J. Kurian ◽  
N. Rini ◽  
M.S. Liew ◽  
A. Whyte
Keyword(s):  
Water Depth ◽  
Model Tests

Model Tests With the HVS Semisubmersible for Dry Tree Application

2014 ◽  
Author(s):  
Johyun Kyoung ◽  
Chan-Kyu Yang ◽  
Kostas Lambrakos ◽  
Jim O’Sullivan
Keyword(s):  
Model Tests ◽  
Base Case ◽  
Natural Period ◽  
Depth Limit ◽  
Wave Basin ◽  
Induced Motion ◽  
Motion Performance ◽  
Heave Motion ◽  
Keel Plate ◽  
Measured Response

The global hull motion performance of the HVS semisubmersible for dry tree application is investigated with model tests. The HVS semisubmersible, which has been validated for low heave motion and VIM (Vortex Induced Motion) response, was modified for dry tree application. As a base case, the modification includes a keel plate with riser keel guides at the level of the pontoons. The keel plate is optimally designed to increase the hull heave period to compensate for the heave period reduction in the HVS semisubmersible due to the riser tensioners for the dry tree application. The plate also provides additional viscous damping that decreases the heave response at the heave natural period. The model tests were performed to investigate the in-place hull motion performance for the Gulf of Mexico environmental conditions. The pneumatic riser tensioners were modeled using a spring with dual stiffness. Because of the water depth limit in the wave basin, a truncated mooring was used to simulate the full scale prototype mooring system. An alternate modification to the HVS semisubmersible that includes pontoon plates was also tested and the measured response was compared to the response of the base case. The measured hull responses were correlated with MLTSIM, a Technip in-house nonlinear time-domain 6-DOF motion analysis program.

The Ocean Cleanup System 001 Performance During Towing and Seakeeping Tests

2019 ◽  
Author(s):  
Joost Sterenborg ◽  
Nicola Grasso ◽  
Rogier Schouten ◽  
Arjen Tjallema
Keyword(s):  
Fluid Structure Interaction ◽  
Model Tests ◽  
Operating Conditions ◽  
Image Correlation ◽  
Plastic Pollution ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Wave Basin ◽  
Floating System ◽  
Floating Systems

Abstract One of the aims of The Ocean Cleanup is to develop technologies to extract plastic pollution from the world’s oceans. Several concepts of passive floating systems were considered that are supposed to confine plastics to ease their collection. Such concepts consist of a floating member and a submerged flexible skirt and have in common that their span is generally more than 500 meters. Consequently, fluid-structure interaction plays an important role in the response of such a floating system. To support numerical simulations, MARIN carried out extensive model tests on a 120 meter system section of the final concept, with focus on the fluid-structure interaction (FSI) of the submerged skirt in operating conditions and in towing configuration. The ability to capture plastics was not investigated in these model tests. Novel for wave-basin tests were non-intrusive measurements using underwater Digital Image Correlation (DIC) to obtain the displacements and deformations of the flexible skirt. DIC proved to be a capable measurement technique for this type of structure in combination with a wave basin. Detailed quantitative data on skirt motions and deformations were delivered and the last concept of the cleanup system was tested in the towing configuration and operational configuration.

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