with the down-hole approach using a geophone lowered into a borehole and several clamping analyses made at intervals during which shots are made from the wellhead and data collected. The clamping procedure is then made in the reverse mode where shots are recorded at different intervals up the well. The other version of borehole seismic survey considers data collection in adjacent boreholes. While one borehole is used to make several wave sources

the other is used to record the data as the seismometer is lowered down the borehole. Two-borehole approach navigates several sedimentary layers apart while the single borehole approach uses the vicinity assessment