A method and apparatus suitable for coupling seismic or other downhole sensors
to a borehole wall in high temperature and pressure environments. In one embodiment,
one or more metal bellows mounted to a sensor module are inflated to clamp the
sensor module within the borehole and couple an associated seismic sensor to a
borehole wall. Once the sensing operation is complete, the bellows are deflated
and the sensor module is unclamped by deflation of the metal bellows. In a further
embodiment, a magnetic drive pump in a pump module is used to supply fluid pressure
for inflating the metal bellows using borehole fluid or fluid from a reservoir.
The pump includes a magnetic drive motor configured with a rotor assembly to be
exposed to borehole fluid pressure including a rotatable armature for driving an
impeller and an associated coil under control of electronics isolated from borehole pressure.