| 摘要 |
The invention relates to at least one transmitter coil in combination with measuring equipment and method for mapping the geology in an underground formation (2) by means of transient electromagnetic sounding. The measuring equipment (1) comprises a transmitter circuit 4 with a current source for generating an electric current and a transmitter coil (6; 28; 30); a switch for connecting the current source to the transmitter coil during operation so that an electric current is generated in this one, said current builds up a magnetic field in the formation (2), and for cutting off this current again so that the built-up magnetic field in the formation decays; and a receiving circuit with a receiving coil for registering the voltage induced over the receiving coil. By placing the receiving coil (7) in an area (19) where the magnetic field strength is small, the transmitter coils (6; 28; 30) are placed closely above each other, the wire (24; 25) of the transmitter coil (6; 28; 30) is composed of a number of electrically insulated cores (23), and there is a preamplifier (17) for amplifying the registered voltage (V Rcoil ) from the receiving coil (7) and the second electrical switch (21) for disconnecting the connection between the receiving coil (7) and the preamplifier (17), a measuring equipment can be provided that is so compact that it can be used for e.g. airborne transient sounding. |
