The Experimental and Theoretical Study of a Tension Leg Platform in Deep Water

1976 ◽  
Author(s):  
Nobuyoshi Yashima
Keyword(s):  
Deep Water ◽  
Theoretical Study ◽  
Tension Leg Platform

Pitch/Roll Static Stability of Tension Leg Platforms

2010 ◽  
Author(s):  
Ning Xu ◽  
Jun Zhang
Keyword(s):  
Gulf Of Mexico ◽  
Deep Water ◽  
Important Implication ◽  
Static Stability ◽  
Tension Leg Platform ◽  
Dynamic Simulations ◽  
System A ◽  
Different Types ◽  
Ocean Conditions ◽  
Righting Moment

Severe hurricanes in recent years have raised concerns about the safety and the robustness of the Tension Leg Platform (TLP) concept in the deep water Gulf of Mexico. This study investigates the static stability of different types of TLPs representing those deployed in the Gulf of Mexico, under three different scenarios. That is, a TLP with an intact tendon system, a partially damaged tendon system, and a completely damaged tendon system. The two types of TLP chosen for this study are the conventional four-leg TLP (C-TLP) and the Mono-column TLP. To avoid buckling and yielding occurring in a tendon, the maximum righting moment provided by an intact or partially damaged tendon system is reached when the tension in one or more tendons on the down tension leg becomes zero or when the tension in one or more tendons on the up tension leg reach the yielding strength. This definition leads us to identify the most sensitive directions of met-ocean conditions to a TLP with an intact or partially damaged tendon system. Hence, our finding may also be used in the study on the dynamic simulations of a TLP. The righting moments of each TLP in the three different scenarios are respectively computed and compared with related wind-induce static upsetting moment at certain velocities. By comparing their ratios, the static stability of a TLP and the redundancy of its tendon system may be revealed, which has important implication to its design.

Benthic foraminiferal zonation in deep-water carbonate platform margin environments, northern Little Bahama Bank

1988 ◽  
Vol 62 (01) ◽  
pp. 1-8 ◽  
Author(s):  
Ronald E. Martin
Keyword(s):  
Deep Water ◽  
Benthic Foraminifera ◽  
Carbonate Platform ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Near Surface ◽  
Sediment Gravity Flows ◽  
Gravity Flows ◽  
Platform Margin ◽  
Water Carbonate

The utility of benthic foraminifera in bathymetric interpretation of clastic depositional environments is well established. In contrast, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 piston core tops and grab samples collected along two traverses 25 km apart across the northern windward margin of Little Bahama Bank at depths of 275-1,135 m. Certain species and operational taxonomic groups of benthic foraminifera correspond to major near-surface sedimentary facies of the windward margin of Little Bahama Bank and serve as reliable depth indicators. Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators, being most abundant at depths >1,000 m, and are found in lower slope periplatform aprons, which are primarily comprised of sediment gravity flows. Reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are most abundant at depths <300 m, reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines, rosalinids, and discorbids are abundant in periplatform ooze at depths <300 m and are winnowed from the carbonate platform. Increased variation in assemblage diversity below 900 m reflects mixing of shallow- and deep-water species by sediment gravity flows.

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