Abstract: A method of acquiring and processing seismic data for repetitive monitoring of displacement of fluids impregnating a reservoir deep in the sub-surface below the surface weathered zone comprises the steps of: making at each point of a predetermined grid on the surface a vertical axis shallow borehole in the earth above the reservoir passing through the surface weathered zone; positioning in each borehole along its vertical axis a plurality of fixed receivers adapted to be connected separately to a seismic recorder on the surface; emitting near each borehole seismic waves into the earth by means of an emitter on the surface or close to the surface near the vertical axis of the borehole; recording for each borehole by means of receivers placed in the borehole the direct incident seismic waves and the seismic waves reflected at the interfaces of deep strata of the sub-surface, each receiver providing a separate record of an incident wave and a plurality of reflected waves; and carrying out the following processin