  In order to detect the gravitomagnetic clock effect by means of two
counter-orbiting satellites placed on identical equatorial and circular orbits
around the Earth with radius 7000 km their radial and azimuthal positions must
be known with an accuracy of delta r =10^{-1} mm and delta phi =10^{-2} mas per
revolution. In this work we investigate if the radial and azimuthal
perturbations induced by the dynamical and static parts of the Earth' s
gravitational field meet this requirements. While the radial direction is
affected only by harmonic perturbations with periods up to some tens of days,
the azimuthal location is perturbed by a secular drift and very long period
effects.It results that the present level of accuracy in the knowledge both of
the Earth solid and ocean tides, and of the static part of the geopotential
does not allow an easy detection of the gravitomagnetic clock effect, at least
by using short arcs only.
