Propagation Resistivity (MPR) tool makes multiple measurements
of formation resistivity using an array of antennas
that propagate multiple electromagnetic signals at different
frequencies. Every propagation and induction log is
characterized, among other things, by the distance from
the tool at which it measures, by the vertical thickness
within which it measures and by its system to compensate
for mechanical changes, bore-hole effects and position.
MPR tool was the first tool to innovatively employ unique
digital technology and integral antennas to accurately
and reliably measure true resistivity even in thin dipping
reservoirs invaded by mud filtrate. MPR is a deep reading,
thin bed tool. The depths at which it investigates into
a formation and under many conditions, range from very shallow
to very deep. Well beyond zones damaged by mud filtrate
invasion and its vertical resolution, or thickness within
which it can accurately read resistivity and unaffected
by surrounding shoulder beds is on the order of inches.
MPR is a compensated propagation resistivity tool. It uses
symmetric pairs of transmitting antennas, above and
below the receivers to compensate its measurements.
This is superior to using software algorithms to interpolate
average signals from asymmetrically positioned transmitters.