BESEDIN D.E., VERBITSKAYA O.A., PAVLOV A.YU., PURUNDZHAN N.A.
“Peter Gaz” Ltd., Russia

The purpose of metocean survey is collecting of sea and atmospheric characteristics necessary for design, building and exploitation of marine constructions.

Following characteristics list is accepted: current velocity and direction, water temperature and salinity, sea level, wave parameters, wind velocity and direction, air temperature, air humidity and air pressure.

Observation of mentioned parameters must be carried out continuously for declared period. This leads special requirements for metocean survey: autonomous high-reliability equipment must be used; observation period can’t be hastened by attraction of additional funds and productive capacity as it is possible in other types of survey.

Planning of metocean survey includes determination of measurements duration, station service interval, measured parameters list and requirements to gauge accuracy; selection of equipment type, stations location and deployment type. At that, following factors must be taken in consideration: design information, local geographical characteristics (bottom relief, coast line shape, known features of hydrological and meteorological condition), human activity (fishing, navy actions and others).

Survey area can be divided on three parts: Shtokman field, region of underwater route (gas pipeline) and approach zone, where gas terminal will be built. Research along gas pipeline route must, above all, cover near bottom layer. Therefore 10 bottom stations equipped by single-point current, temperature, salinity and (sometimes) level meters were deployed on section between gas field and shore. RCM 9 was used as multiparametric measuring system.

On Shtokman field and approach zone it is particular interesting to investigate waves and meteoconditions. Several wave gauge, measuring key parameters, were deployment there (RDI ADCP “Workhorse”, Fugro Oceanor “Wavescan” buoy). On coastal area stations were deployed inside Teriberka bay, on entrance to the bay, in open sea on different distance from the shore. That allows getting conception of propagation and transformation of surface waves. Meteorological measurements were carried out with coastal weather station Aanderaa AWS 2700 and surface buoy “Wavescan” deployed on Shtokman field.

Inline frames were used for station deployment because of big depth and bottom roughness. Only one station – “Wavescan” buoy was deployed on surface using special S-type mooring line.

Besides single-point, profile measurements also were carried out. These were currents profiles (on several stations) and temperature and salinity profiling during cruises.

Planned duration of field survey was 1 year, station service interval – 3 months. That allows receiving initial data series needed for mean and extreme parameter values estimation and harmonic tidal analysis.

Oil and gas of Arctic shelf 2008