Ministry of Natural Resources and the Environment of the Russian Federation  
The Federal Subsoil Resources Management Agency

Measurements of the natural electric field

    Sulfide deposits on the ocean floor, like sulphide deposits on land, are sources of negative anomalies of the natural electric field, and these anomalies can be measured. That is why profiling for the purpose of measuring the natural electric field (NF) is currently the most informative method of searching for both active and inactive PS ore fields.

    As a technical tool for carrying out electrical prospecting (NF) the PMGE JSC uses the MAK-1M complex in full with onboard and underwater equipment. Profiling is carried out simultaneously with the sidescan sonar "MAK-1M".

    The electronic board for measuring the NF (NF measuring device), developed in JSC PMGRE, is inserted into the underwater block of the "MAK-1M" complex to the available free connector without any modifications. For the NF meter, a new hardware and firmware registration was developed, which allows registering and displaying NF values and outputting them to a separate monitor. Simultaneous use of the two channels allows obtaining more complete and reliable information on the NF anomalies and avoiding the loss of information in the event of failure of individual electrodes.

    Vertical streamers manufactured by OOO Pskovgeocable are used to measure the NF.

    The corridor of the height from the bottom in which the deepwater submersible is towed is determined by the length of the used vertical streamer and is on the average 60-90 m. Its average speed when moving along the profiles is 0.8-1.4 knots, which ensures the acceptable conditions for measuring the potential of the natural electric field.

Below are examples of graphs of the measured NF on the profile (Fig. 1) and the sidescan sonar evidence card with anomalies (Fig. 2 and Fig. 3).

Fig.1. Graphs of measured parameters of the NF on the profile.




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