Patent ID: 7673682

Claim:
A geophysical sensor apparatus, comprising: an elongated well casing capable of being emplaced in a borehole; a sensor located outside the well casing for detecting a geophysical parameter at an emplacement depth; means for communicating detection data from the sensor out to a remote monitoring location; a centralizer affixed to a section of the well casing so that during emplacement the well casing and the sensor are spaced from the borehole sidewalls to protect the well casing and the sensor from damage; and at least one additional sensor(s) located outside the well casing and protected by the spacing produced by the centralizer, wherein the sensors are all located at the same section of the well casing and thus the same emplacement depth, and are of different types for detecting different geophysical parameters at the same emplacement depth, wherein the sensors are of two types including an electrical resistance tomography (ERT) electrode and a seismic receiver.