A Methodology for DP Capability Studies on Remotely Operated Vehicles

2017 ◽  
Author(s):  
Juan A. Ramírez-Macías ◽  
Rafael E. Vásquez ◽  
Asgeir J. Sørensen ◽  
Svein Sævik
Keyword(s):  
North Sea ◽  
Three Dimensional ◽  
Dynamic Positioning ◽  
Remotely Operated Vehicles ◽  
Environmental Loads ◽  
The North ◽  
Surface Vessels ◽  
The North Sea ◽  
Position And Orientation ◽  
Surface Vessel

Dynamic Positioning (DP) capability studies are used to assess if a vessel has sufficient thrust capacity to withstand environmental loads while keeping its position and orientation at a specified set-point or path. These studies are usually performed on ships and other DP-controlled surface vessels; consequently, standards and procedures for these are widely known. In this work, a methodology for conducting a DP capability study for Remotely Operated Vehicles (ROV) is presented. Due to the nature of ROV operations, a DP capability study should include different features that are not common to surface vessels. In this case, an ROV connected to a surface vessel through a tether is considered. During operation, the tether is subject to varying current loads that are accumulated along the water column and transferred to the vehicle. Therefore, the ROVs thrusters must be able to withstand, in addition to its own drag, three-dimensional loads due to three-dimensional currents and umbilical-related loads. To illustrate the methodology, two case studies are considered: the DP capability of an ROV that has to operate in the Colombian Caribbean and an existing ROV operating in the North Sea.

DP Safety for Offshore Drilling and Well Intervention Vessels

2008 ◽  
Author(s):  
H. Chen ◽  
T. Moan
Keyword(s):  
North Sea ◽  
Barrier Function ◽  
Dynamic Positioning ◽  
Barrier Method ◽  
Offshore Drilling ◽  
The North ◽  
Well Integrity ◽  
The North Sea ◽  
Norwegian Continental Shelf ◽  
Barrier Model

Barrier method is used to model the safety of dynamic positioning (DP) operation for mobile drilling and well intervention vessels. Two barrier functions are identified which are aimed to prevent loss of position and to prevent loss of well integrity given a loss of position, respectively. The first barrier function is analyzed in this paper. Deficiencies are identified based on the DP incidents on the Norwegian Continental Shelf, and recommendations are proposed to strengthen each barrier element which can improve the safety of DP operations for drilling and well intervention vessels working in the North Sea. The barrier model and recommendations are also valid to DP operations on drilling and well intervention vessels worldwide.

UNDERWATER BLOWOUT OIL COLLECTION

1977 ◽  
Vol 1977 (1) ◽  
pp. 293-295 ◽  
Author(s):  
Rich H. Westergaard
Keyword(s):  
Feasibility Study ◽  
North Sea ◽  
Oil Spill ◽  
Oil Production ◽  
Offshore Drilling ◽  
The Past ◽  
The North ◽  
The North Sea ◽  
Surface Vessel

ABSTRACT Oil production in the North Sea and some other potentially important areas is much more difficult than offshore drilling was in the past. It is assumed that the difficulties are properly compensated so that blowout probability is not increased. The very much higher productivity of the wells, the expected longer duration of a blowout and the greater difficulties of surface containment obviously increase the probable oil spill volume. Exactly how much it is increased statistically is not known. A factor of 100 is suggested. For this reason, such areas need a much better oil spill defense than used in the past in other areas. The author is engaged in a feasibility study on underwater collection for control of underwater blowouts. The proposed equipment consists of a heavy submersible rig which can place a collection bell over the blowout orifice: the petroleum is then ducted from the bell to a surface vessel where the gas is burned and the oil collected or burned.

scholarly journals Numerical modelling of physical processes governing larval transport in the Southern North Sea

2013 ◽  
Vol 10 (5) ◽  
pp. 1765-1806 ◽  
Author(s):  
M. C. H. Tiessen ◽  
L. Fernard ◽  
T. Gerkema ◽  
J. van der Molen ◽  
P. Ruardij ◽  
...  
Keyword(s):  
North Sea ◽  
Sea Water ◽  
A Priori ◽  
Three Dimensional ◽  
Larval Transport ◽  
Absolute Amount ◽  
Annual Variability ◽  
The North ◽  
The North Sea ◽  
Selection Of

Abstract. A three-dimensional hydrodynamic model (GETM) was coupled with a particle tracking routine (GITM) to study the inter-annual variability in transport paths of particles in the North Sea and English Channel. For validation, a comparison with observed drifter trajectories was made. The aim was to investigate to what extent variability in the hydrodynamic conditions alone (reflecting passive particle transport) contributed to inter-annual variability in transport of eggs and larvae. In this idealized study, no a-priori selection of spawning grounds or periods was made and no active behaviour (vertical migration) or mortality were included. Egg and larval development towards coastal nursery areas was based solely on sea water temperature, while settlement areas were defined by a threshold water depth. Results showed strong inter-annual variability in drift direction and distance, caused by a combination of wind speed and direction. Strong inter-annual variability was observed both in absolute amount of settlement in coastal areas, as well as in the relative importance of the different areas. Settlement in the western Dutch Wadden Sea not only showed inter-annual variability, but patterns were also variable within each year and revealed seasonal changes in the origin of particles.

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