RE: Well logging/Tracer Operations

["Wesley M. Dunn" <WDUNN@brc1.tdh.state.tx.us>]

Actual logging is done with sealed sources (Cs-137 for gamma logs, Am-
241(Be) for neutron logs).  However, they also use various isotopes 
for tracer operations to determine oil field flow characteristics.  I-
131 is a very commonly used tracer isotope.  You can put it down this 
hole, and monitor another hole to see how the oil moves.

If you have poor flow, you can do a "fracture" job, whereby you push 
a lot of Ir-192 tagged sand into the zone, hoping to crack it for 
better oil flow.  By monitoring the Ir-192, you can see whether it is 
working or not.

If you really want to get complex, you pour different isotopes down 
different holes.  This can give you a very good diagram of the field 
characteristics.

(Disclaimer: I haven't much effort in this area for some time, so my 
descriptions are necessarily general - and I can't find my best 
reference book at the moment)

Wes

> Date sent:      Wed, 4 Sep 96 19:08:39 -0500
> Send reply to:  radsafe@romulus.ehs.uiuc.edu
> From:           Slaback@micf.nist.gov
> To:             Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> Subject:        RE: crosspost: OEM: Carcinoid tumour of thymus / radioisotope exposure

> My first impression is that there is a major
> misunderstanding by this individual.  These
> sources are usually sealed sources so the description
> of 'spilling on clothing...' etc would seem 
> erroneous.
> 
> Is anyone aware of unsealed usage of these long-
> lived radionuclides in well logging?
> I believe some (tritium?) have been used in
> injection/dilution studies.  Would appreciate
> comments from well logging experts.
> 
> A little risk adds spice to life.
> slaback@MICF.NIST.gov
> 
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Wesley M. Dunn, CHP                        512-834-6688
Deputy Director, Licensing                 512-834-6690 (fax)
(Texas) Bureau of Radiation Control        wdunn@brc1.tdh.state.tx.us
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