John:
I have purchased slotted schedule 80 PVC pipe and it worked quite well. The
pipe also comes threaded so that it can be reused. It is available at water
well establishments, as well as companies that cater to environmental
measurements.
Dutch
----- Original Message -----
From: John Bishop <[EMAIL PROTECTED]>
To: Segmin@Lists. Geosoft. Com <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>; Steve Collins <[EMAIL PROTECTED]>;
<[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>;
<[EMAIL PROTECTED]>
Sent: Wednesday, May 03, 2000 6:34 PM
Subject: [SEGMIN]: slotted casing
> Colleagues,
>
> I intend to run some test DHEM and DHMMR surveys over a deposit which
> contain several different types of sulphide mineralisation. To assist the
> interpretation, we want the intrinsic conductivities of the ores and host
> rocks for the EM surveys and the intrinsic resistivities for the MMR
(these
> not always being the inverse of each other in a complex earth). Thus we
> intend to do some conductivity and resistivity logging. Ground conditions
> are poor and the holes will need to be cased. For the resistivity logs,
the
> casing will need to be slotted.
>
> I have the following questions/concerns:
>
> 1. Can we obtain 'reasonable' resistivities through slotted casing? (I
> appreciate that the slots should overlap, but fear that the casing may add
> a 'DC shift' to the data.)
>
> 2. What is the optimal slotting pattern? (For downhole IP, I have used
> slots 15cm-20cm [6"-8"] long with ~5cm [2"] overlap which spiral along the
> casing with a 120 degree separation between slots. This has produced
useful
> results, but they may not be optimal.)
>
> 3. Any suggestions on effective ways to cut the slots?
>
> thanks,
>
>
> jb
>
> John Bishop
> Mitre Geophysics Pty Ltd
> P.O. Box 974, Sandy Bay, 7006, Australia
> ph: +613 6225 4556 fax: +613 6225 4553
> email [EMAIL PROTECTED]
>
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