Some of the longest threads on the E-T forums have been on the subject of measuring well depth. Your inquiry is a 'bit' (LOL) different in that it seems the drill bit is still in the hole.
In such cases, most would probably just keep track of the number / length of the drill stack. My well driller knew the drill depth by looking at his truck to count the number of shafts in use, and then looked at the rig for the last fraction.
@VE1BLL,
Thanks, the hole is actually a shallow (shot) hole for land seismic acquisition, it has been an issue with my crew for the drillers has been reporting fictitious values.
So, i am looking for a way to control such occurrences.
@MacGyverS2000,
Yes, you are right.
But, this is not what you can discover real time or close to real time, because it takes some days between drilling and recording.
The true depth is important for accurate statics correction.
You're trying to solve a problem that has a several-day lagtime with a project that will months to design/test, assuming it can be done for a reasonable amount of currency. Honestly, I think your best bet is to identify the drillers who are causing issues, tell them to shape up or ship out, and start applying a little hard love. Your problem will be resolved within a few weeks, not months (or more), and it will cost you nothing out of pocket.
Bit of a rant, but I see employers willing to ignore the problem employees more and more these days, even to the detriment of the operation as a whole. Short sighted, IMO.
Video recorder, security type. That's the only technical solution I can think of that would be easily practical.
A more impractical solution would be an acoustic sonar to fire down the hole (assuming dry) and record GPS location and time & date, and the measured distance (depth). Post drilling of course.
I agree with all of the above suggestions. And definitely a DVR (Digital Video Recorder) with a camera solves the problem. Then you just use the count-the-drill-string method to see the precise depth reached. It can additionally be used for security purposes.
There are scads of DVRs specifically designed to be used in vehicles with DC power inputs. Start with ebay.
