Mounting sensors on a borehole casing pipe

An improved device is disclosed for the seismic monitoring of a petroleum deposit having at least one signal receiving unit fixed to the outside of a pipe 39 before it is cemented in a borehole passing through the monitored zone. On its outer surface said pipe carries at least one housing defined by projecting elements (longitudinal members 49, 50, and stops 40, 42) where the reception unit is embedded and fixed so as to protect it from the shocks or compressive forces which may occur during lowering of the pipe into the well. Each reception unit comprises a support assembly with cavities for sensors, electronic cards for amplying the signals delivered by said sensors and a sealed external case 34 which is easy to position and which is held firmly in position by embedment in said housing. A multi-conductor cable 20 is used for example for connecting the reception unit to the surface.