[ RadSafe ] NORM in CO2...

[Dan W McCarn]

Dear Mike:

Source of CO2: The bulk of the CO2 probably comes from the respiration of
bacteria in the oil & gas reservoir. CO2 reacts with water (H2O + CO2 <=>
H2CO3)and speciates to form carbonates H2CO3 - HCO3- and CO3-- in solution.
The HCO3- forms an aqueous species with calcium, keeping it in solution as
well as lowering / controlling the pH with increasing partial pressure of
CO2.

Radium: Since oil and gas deposits are formed in chemically reducing
environments, they syngenetically entrain finely divided uranium along with
it as a stable mineral, uraninite, UO2, a U+4 species. As the uranium
decays, the radium is more mobile and is probably initially cation-exchanged
onto surfaces e.g. clays, but with the increasing concentration of NaCl
brine, Ra++ dislodges and is brought into solution.  This is much like
adding NaCl salt to the ion-exchange resins of a water softener to dislodge
the Ca++. The NaCl brine forms/evolves in oil and gas fields from the high
confining pressures.  The high osmotic pressure forces clean H2O through the
semi-permeable rock but retains the anions / cations, principally NaCl, thus
the evolution of oil-field brines. 

Scale: CO2 evolves or degasses from the high-pressure water / gas mixture as
it is brought to the surface with gases effervescing from a watery solution
which also sometimes carries extremely toxic H2S with it (It also speciates
as a diprotic acid, just like H2CO3). With a significant reduction in
partial pressure of CO2, the Ca++, then in solution, plates-out as scale,
co-precipitating the Ra++ along with it. With the release of pressure, the
pH rises.  When it reaches atmospheric equilibrium with CO2, the pH has
shifted from about 4 or 5 to over 8 and has precipitated almost all of the
available calcium.

Thus, NORM and TENORM from scale deposits in piping. Yippee!

Best!

Dan ii


--
Dan W McCarn, Geologist
7 Likely Place
Santa Fe, NM 87508-5938
+33.(0).6.47.86.05.25 (Mobile - France) 
+1-505-240-6872 (Skype - New Mexico) 
HotGreenChile at gmail.com (Private email)

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf
Of Brennan, Mike (DOH)
Sent: Tuesday, August 18, 2009 12:36
To: radsafe at radlab.nl
Subject: RE: [ RadSafe ] NORM in CO2...

How is the CO2 made?  If is made from natural gas, that might be the
source.  As I understand it, Ra is entrained/dissolved in natural gas,
and comes out of the ground with it.  Ra plating out on natural gas
pipes sometimes is raised as a NORM issue.  

Another thing to check is that the CO2 REALLY does have Ra-226 in it,
and that it is not the steel in the tank, or operator error.  I once had
a member of the public call, extremely agitated about the "high
readings" he was getting on his CDV GM.  When I asked him what scale he
was on there was silence for a while, then, "Oh."   

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of Brian G. Rees
Sent: Tuesday, August 18, 2009 11:12 AM
To: radsafe at radlab.nl
Subject: [ RadSafe ] NORM in CO2...

I have a question:  Why would CO2 have elevated Ra-226?  I'm familiar
with Rn in propane (similar boiling points), but what about Ra-226?

Thanks in advance,
Brian Rees
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