Multiplexing electromagnetic transmitters for monitoring of permanent reservoir

A system that comprises:

• a cable disposed within a borehole that penetrates a subterranean formation, the cable having a plurality of transmitters along a shared conductive loop, wherein each of the plurality of transmitters is coupled to a corresponding frequency-dependent material or device;
• a surface interface coupled to the cable, the surface interface having program code stored thereon executable to cause the surface interface to,
• apply a first drive signal to the cable to excite the plurality of transmitters to obtain a first measurement, the first drive signal having a first frequency and a first amplitude;
• and
• apply a second drive signal to the cable to excite the plurality of transmitters to obtain a second measurement, the second drive signal having a second frequency and a second amplitude, wherein at least the first frequency is different from the second frequency, or the first amplitude is different from the second amplitude;
• and
• a processor coupled to the surface interface, the processor having program code stored thereon executable to cause the processor to,
• receive the first and second measurements from the first and second drive signals exciting the plurality of transmitters respectively;
• and
• to derive, based at least in part on the first and second measurements, a resistivity distribution around the borehole.