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Hi all,

Is there any proof that neutron bombardment (like from the density tool) can alter the formation and can this reduce production or permeability? What a bout MRIL (which uses strong magnets if I recall correctly)?

Thanks for your thoughts!

I've personally never heard of this occurring. Mostly it's the drilling mud that largely alters the formation or pressure drops, minor fracturing etc. I think the effects of neutron bombardment and magnetics will be dwarfed by those alterations caused during the drilling. Drilling exerts much more force on a formation than these wireline sensory tools can do in my opinion

Neutron and density tools activated the formation radioactively up to their depth of investigation. The activated radioactivity decays very quickly with time, which may be few minutes. If logging tools are stopped while logging, then you will see high Gamma ray at that particular depth, and neutron & density tools reading will be affected too. I don't think anything happen other than this happens.