Magnetic Markers on Steel Cable

[boreholelogger]

I was wondering if anyone new where I could find some information on a system which I have heard exists, that magnetises sections of a wire-line cable (Steel Cable). For example magnetises a small section on the cable every 10ft. The cable is then winched in and out of a muddy hole in the ground and apparently you can use hall effect sensors to measure the number of 10ft sections that are either going into or out of the borehole (Well).

Any help would be appreciated. If more explanation is required then please do not hesitate to ask.

 

[boreholelogger]

Hi All,
I had such an overwhelming response for this question.........he he.

Anyway, I have since designed a system that can magnetically mark and un-mark steel geophysical logging cable at various intervals (wireline / oil & gas exploration / Minerals exploration / Borehole logging). I have also designed a circuit to read the magnetic mark on the cable (Very important too ;-)).

If anyone needs anymore information on it or has a use for it. Let me know.

 

[itsmoked]

I would presume you just apply a current (arc welder) to a laid out section. This would magnetize it in one direction. Then just reverse the process every 10 feet. Makes no sense to me when a follower would seem to be more convenient.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[boreholelogger]

That isn't how I would do it, but anyway. What do you mean by a follower would seem more convenient?.

 

[itsmoked]

Gesh that wasn't very clear was it?

What I meant was some sort of simple roller or sheave that your cable runs past(follower), which turns, and counts how many feet have gone by in either direction.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[boreholelogger]

Ah yes I see what you mean't now. An encoder for measuring the amount of cable that has past over the V pulley's. Yes I am using a US Digital optical encoder, they are quite good and really inexpensive. They also let you know which direction the cable is moving using quadrature signals, which we can decode. We have been using them for years now and haven't had a problem with them.

 

[itsmoked]

Seems that the magnetic method would be cumbersome at some level.. But intriguing!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[boreholelogger]

Sorry I missed your point. Yes we normally use encoders for desert work and other non-icy and non-muddy work and they are quite good. Although in the freezing areas, like northern Canada and Russia. The Ice freezes on the cable as it comes out of the wet, warmer boreholes and then builds up on the encoder wheel effectively increasing the pulley's circumference, and/or causing the cable to slip on the pulley and therefore producing depth errors. So we designed this magnetic cable marking system which allows the cable to be marked at specified increments and then these marks can be used as a true measurement of the depth and compared against the encoder readings. It is used mainly to let you know if the encoder wheel has gradually slipped or increased in size over the period of time logging, or whether the cable has slipped a great deal in a certain section of the data logging of the borehole.

 

[BJC]

Does the magnetic fild alter the field in rock you logging? The first time down the hole the probe is reading virgin rock, the next time and on the way up it's reading a field that you may have altered.

 

[boreholelogger]

The magnetic field that is induced in the cable is approximately 2 - 4 Gauss at the edge of the cable which is about 4 - 8 times the earths magnetic field (0.5 Gauss), so the effect would be negligible, if any at all. You have to dramtically amplify the signal received from the sensor to be able to read it, let alone it having an effect on a rock formation.

 

[pearson30]

I know of a company Kerr Measurement(now Benchmark Wireline) that has made these in the past. They are currently is transistion to a new type system. Unfortunatly I am in need of a system like this right now. Are you currently manufacturing a system like this or having you design manufactured?

 

[boreholelogger]

Hi pearson30, contact Matt Edmonds from Auslog Pty Ltd, he should be able to help you out.

We have already sold a few of them in the minerals industry. Although our budget and management never let us continue working on it to make the cable marker Automatic. Although I don't perceive that making this unit mark the cable automatically to be a big job, we just need the go ahead from management to do it.

At the moment to use the system, you have to mark the cable manually. For example, spool 100 meters off the winch and press a button to mark the cable.

Let me know what you think.