Underground reservoir monitoring system

A device for monitoring a reservoir underground comprising:

• a surface control console,
• a power source to supply an alternating current flowing through the reservoir through a casing,
• a first toroid coil mounted underground and outside of the casing, wherein the first toroid coil is configured as a first transmitter to generate an alternating current flowing through the casing, and the casing passes through the first toroid coil,
• a second toroid coil configured to operate as a first receiver and mounted underground outside the casing, and the casing passes through the second toroid coil, and
• a processor configured for calculating a parameter selected from the group consisting of a first parameter, a second parameter, and a combination thereof, wherein the first parameter is a parameter of an alternating current induced by the first toroid coil flowing along through the casing selected from the group consisting of phase velocity, group velocity, phase difference, amplitude decay, time difference, and combinations thereof, while the alternating current passes through the reservoir through the casing based on a current signal, and the second parameter is selected from the group consisting of reservoir resistivity, which is computed from the first parameter, reservoir water saturation, which is computed from the reservoir resistivity, and a combination thereof, wherein:
• the second toroid coil is configured to measure a voltage parameter induced by the alternating current signal flowing through the casing, and the voltage parameter is selected from the group consisting of real part, image part, phase, amplitude, and combinations thereof,
• at least one of the first and second toroid coils is capable of transferring data to the surface control console and receiving an operation command issued by the surface control console;
• and
• the first parameter is calculated by the processor based on the voltage parameter.