AW: [ RadSafe ] DHS Tests of Radiation Detectors WereInconclusive, Report Says

Doug Aitken jdaitken at
Fri Mar 7 08:54:27 CST 2008

I think we can agree that the problem is not trivial. As you stated in an
earlier e-mail, trying to accurately determine lithology from a downhole
(passive) GR measurement (even a spectral one) is not really possible. Which
explains why we cart around a bunch of sources and neutron generators to
wellsites and stick them in the ground.... and do a bunch of pretty
sophisticated number crunching with our surface systems to come up with
usable information. It is a whole lot easier to pull out a core and do a lab
analysis (but time is money, and the industry now expects us to "do it all"
in real time during drilling!)

As obviously the radiation detectors in these tests have to rely on passive
measurements, it is all down to the spectral analysis and the library of
"standards" (known spectra)  built into the detection system. I would
surmise that your term "learnings" is the process of developing these
"standards". The only assistance I would deem reasonable would be to advise
what particular isotopes (or rather, range of isotopes) were to be detected)
to the manufacturer so they could optimize their library of standards in
advance of going to the test site.

And obviously, some time would be needed at the beginning of the test for
the operator to "calibrate" their instrument to the environment

But the implication made was that there was some "collusion" and that the
operators might have been given rather more information on the particular
"orphan" to be detected in any particular test.

Which goes well beyond "learning"....

Doug Aitken     Cell phone: 713-562-8585
QHSE Advisor
D&M Operations Support           
Schlumberger Technology Corporation
300 Schlumberger Drive
Sugar Land TX 77030

Home office: 713-797-0919  Home Fax: 713-797-1757

-----Original Message-----
From: Dan W McCarn [mailto:hotgreenchile at] 
Sent: Thursday, March 06, 2008 10:16 PM
To: 'Doug Aitken'; 'Sandy Perle'; 'Franz Schönhofer'; 'Brennan, Mike (DOH)';
radsafe at
Subject: RE: AW: [ RadSafe ] DHS Tests of Radiation Detectors
WereInconclusive, Report Says

<< IMHO, anything beyond the normal calibration and a field check with the
user's own references (and NOTHING supplied by the persons evaluating the
instrument performance) would be "fudging"......>>

Funny that you should say that so directly, because as a geologist, I would
tend to call those "learnings".  Field trials are a little different than
other circumstances.  I'm surprised that extensive field trials with both
"known" and "unknown" circumstances were not evaluated into "learnings"
prior to this "Test" in order to incorporate as much information as

Dan ii

Dan W McCarn, Geologist

More information about the RadSafe mailing list