[en] Document available in extended abstract form only. Fluid pressure or hydraulic head measured in wells in geological formations can respond to Earth tidal forces and atmospheric pressure variations. At Andra Meuse/Haute-Marne underground research laboratory located in Bure (France), water level and fluid pressure are measured in several boreholes in the Callovo-Oxfordian clay formation (COX) and in overlying geological formations. One of these boreholes (EST207) is equipped with a multi-packer system monitoring 11 intervals, including 8 in the COX. The recorded fluid pressures in EST207 were analyzed to determine possible Earth tidal responses. In this borehole, the fluid pressure and atmospheric pressure variations data are recorded every fifteen minutes and 6.5 years of such data from 2004/06/02 to 2010/12/31 were analyzed. Various perturbed data, gaps, drift and abnormal data were corrected through a data preprocessing process. Data interpolation and filtering processes were performed to have data available every 15 minutes at 0, 15, 30 and 45 minutes on the hour. A spectral analysis (Fast Fourier Transform) of each pressure data series shows amplitude peaks at frequencies corresponding to various Earth tidal frequencies: diurnal and semi diurnal waves can be identified. Spectral analyses were also performed on the atmospheric pressure data. The solar semi diurnal wave (S2) was identified. The 'Earth Tides ETERNA package' was used to separate the waves according to the frequencies bands. The analyses performed using ETERNA are indicated as 'Earth Tidal Analyses' (ETAN). Tidal parameters are estimated from ETAN: amplitudes A and its standard deviation σ(A)[hPa], phase φ for the main waves in diurnal and semi diurnal frequencies bands before and after atmospheric pressure variations correction. The barometric efficiency (BE) and its standard deviation σ (BE) as regression coefficient is calculated. The atmospheric pressure data are also analyzed with ETERNA; the wave S2 amplitude and phase values usually taken into account as references are in good agreement with values calculated at others sites. This result validates the atmospheric pressure data sets. Having high quality data and multi-year data sets, it was possible to separate several main tidal waves in the diurnal band and in the semi diurnal band. K1, O1, P1, S1 and M2, N2, S2, K2 bands were first taken into account in each series to determine whether they were significant or not. The ETAN results are in good agreement with the spectral analyses results and with these results it can be concluded that the 11 monitoring intervals in borehole EST207 respond to Earth Tidal forces and to atmospheric pressure variations. The ETERNA software allows identifying more tidal waves with more accuracy. In all the intervals, the best identified significant waves are O1, K1, M2 and S2. While the M2 amplitude is not or only slightly perturbed by atmospheric pressure variations and the M2 phase is not, the S2 wave amplitude and phase are very sensitive to atmospheric pressure. After barometric correction, the amplitudes through the borehole are generally decreasing from the bottom to the top. In a preliminary hydrogeological interpretation, the detailed intercomparison of tidal analyses results according to the barometric correction effect, the BE values and the waves identification quality provide a classification of the barometric and tidal responses as a function of the various intervals. These responses were classified into four groups depending on the monitoring intervals in the Dogger, the lower COX, the upper COX and the base of Oxfordian. The BE values show that the greater the clay content of the formation is, the greater the BE values are. The BE values in the Dogger are similar to the values estimated in the Oxfordian. In 2003, Andra investigated earth tides and barometric responses in the Oxfordian of two boreholes, EST203 and EST104. The hydrogeological interpretation in these two boreholes provided estimates of transmissivity and storage coefficient consistent with the pump tests results. In fact Earth tidal and barometric responses in wells can be used to estimate hydrogeological parameters effectively without classical pump test experiments and over a long time period. In the eleven intervals in borehole EST207 and particularly in the COX, the Earth tidal and barometric responses are dependent on the formation geology and the hydrogeological parameters. Preliminary interpretation to derive certain hydrogeological parameters of the COX could be refined. These parameters could be estimated by analyzing the tidal parameters and barometric responses combined with a tidal dilatation model. This tidal dilatation model could also be obtained from measurements of three directional extensometers with suitable equipment. (authors)