CALCULATION OF EXTREME CURRENT VELOCITIES BY THE COMPOSITION DISTRIBUTION METHOD (USING THE EXAMPLE OF THE PILTUN-ASTOKH OIL FIELD ON THE NORTHEASTERN SHELF OF SAKHALIN)

G. V. Shevchenko

A technology of the composition of distributions of both the tidal and non-periodic components developed to estimate possible sea level fluctuations [19] has been modified to calculate extreme summary currents of rare occurrence. The technology is illustrated by the example of current velocities in the region of the Piltun-Astokh offshore oil and gas field on the northeastern shelf of Sakhalin. A large body of instrumental observations performed in 1987—1991 and 1996—1998 allows the adequate estimation of both summer and fall distributions of the non-periodic component in the surface, intermediate, and bottom layers. The tidal component is estimated by precomputing the corresponding 19-year series, which is possible due to a negligible influence of baroclinic effects on the general structure of the tidal flow. It is shown that in summer a major contribution to the summary currents is made by the tidal component and in the fall the nonperiodic component plays an important role, particularly in the intermediate and bottom layers. The estimates obtained for summary currents of rare occurrence can be used to design hydrocarbon production and transportation facilities in this area.