A METHOD OF PROBING DRILL HOLES ELECTROMAGNETICALLY, AND A TRANSMITTER ARRANGEMENT AND A RECEIVER ARRANGEMENT FOR CARRYING OUT THE METHOD

摘要

The invention relates to a method and to a transmitter arrangement for the probing of drill holes (4). The transmitter includes a ground-located conductor loop (1) which is supplied with a current that has a wave shape which includes at least one low frequency (e.g. 200-3000 Hz). The frequency is crystal controlled and normalised to time signals from GPS satellites. The receiver includes coils which function to sense field changes having the sam e frequencies as the transmitter and is housed in the probe (6), said probe being lowered with the aid of a typical drill pipe (5) and lacks signal connection with the transmitter. Instead, the probe includes an accurate quartz clock which is frequently calibrated and which enables the phase of t he received signal to be determined synthetically relative to the phase of the transmitter signal, e.g. by means of a signal processor. Because a typical drill rod is used, the drill hole may have any chosen direction and may even be blocked with sludge, slurry, etc., therewith obviating the risk of the probe becoming stuck in poor rock, as in the case of line-carried probes.