Influence of Metocean Conditions on Marine Operation(s)

Offshore structures, which are placed in the ocean for the exploration and production of resourcesunderneath the ocean floor, are at the mercy of the environment they are subject to by nature. Theseconditions   that   the   structures   may   face   are   the   ocean   waves,   wind,   tidal,   swell   and   current.Earthquakes and Tsunami waves may also occur in the water in certain parts of the world. For thesurvival of these structures, the effects of the environments on them must be known by the designerof these structures and considered in their design specification and material selection.A ship must be able to float in a stable and upright position, move with sufficient speed and also ableto   maneuver at  sea   in   to  accomplish   its  purpose   of  conveying   materials   through   the   ocean.  Inaddition to this, a ship have to also sail in restricted waters and be able to withstand the rigors ofrough weather and wave impact. For a marine vehicle to be designed with these qualities or features,the knowledge of ship dynamics is imperatives. With a good knowledge of hydrostatics, a marine vehicle can be designed to float uprightly in calmwaters. However, ships and other marine vehicles rarely sail in calm water. Waves which are themain source of motions in a seaway, affects the performance of a ship. Thus, a successful design of amarine vehicle depends ultimately on its performance in a seaway. Unfortunately, marine vehiclesare designed based on calm water situation without consideration of the sea and weather conditionsprevailing over the rout the vehicle will operate.The marine  physical  environment  generates  winds,  currents,  and  waves which  are  described bymathematical  models.  Statistical  analysis  is  required   to  analyze  the   data.   The  loads  from  thesephenomenon   are  found  by  measurements,  model  testing,  and   calculations,  using  calibratedmathematical  models  (for   example  the   Morison  equations).  The  actions  of  winds,  currents,  andwaves generate horizontal and vertical forces, which serve as the basis for the design of positioningsystems, such as mooring systems and dynamic positioning (DP) systems.According to Gudmestad (2015), marine operation is an offshore activity performed from a floatinginstallation or a vessel engaged for a specific task in a marine sensitive environment. There are manytypes of marine operations, both in shallow waters, deep waters, and ultra-deep waters. Some of thetypes of marine operations are pipeline installation, pipeline towing, umbilical installations, drilling,well interventions, and coiled tubing intervention and equipment installation subsea. 1

Some common terms used in connection with maritime operations are:i. availability of the vessel/installationii. weather window when the vessel/installation can workiii.  waiting on weather (WOW)iv.  motion compensation andv.  dropped objectsMetocean conditions refers to the combined effect of the meteorology and oceanography. As such,the metocean condition refers to a number of meteorological and oceanographic conditions. Thesefactors include: local surface wind, wind-generated local waves, swell (long-period waves) generatedby distant storms, surface current also generated from the local storms, energetic deep water currentsassociated with low frequency, large basin circulation, and non-storm-related currents, which aresite-specific, such as loop current in the Gulf of Mexico or coastal current in the Norwegian northernNorth Sea.This term paper is centred on discussing the influence of metocean conditions on marine operations.This study takes into accounts the effects of some environmental conditions, such as wave, current,tidal, wind and swel