Ionising radiation, Legislation, Radioactivity, Science

“Dear Aunty, aren’t we at risk from the radioactive sources used in wireline logging?”

Goodness gracious me, no dears, not at all!

It’s true that specialist oilfield services companies will occasionally undertake wireline logging on fracking sites using powerful radioactive sources, but unless you’re standing right next to one, cherubs, there’s no risk to you at all.

Wireline logging involves lowering a radioactive tool into the well to measure the characteristics of a hydrocarbon reservoir.

The radioactive sources that are typically used, sweeties, are called Am/Be sources (Americium and Beryllium) and are a source of neutrons.

The people using them are at greatest risk, because they come into close proximity, dears, but they’re what’s known as ‘classified workers’ whose annual dose of radiation is monitored thoroughly throughout their entire career. Their proximity to the sources is also kept to a minimum because, once removed from the transport package, the are quickly lowered into the well. So the length of time of exposure is limited.

Once the tool is lowered into the well, it naturally gets further and further from the surface and so the distance between the radioactive source and people is increased.

They are what are known as ‘sealed sources’ which means they are encased in protective shielding, and when transported to and from site, they are contained within special protective packages that provide additional safety shielding.

The key words here, cherubs, are: Time, Distance and Shielding.

The likelihood of a member of the public being exposed to ionising radiation from one of these tools is incredibly remote because of these risk minimisation measures. For a start, darlings, it’s unlikely that a member of the public could gain access to a securely fenced drilling compound.

But even walking the dog past a drilling site whilst wireline logging is being conducted won’t cause any threat of harm, my dears, because like the intensity of sound mentioned in one of my posts on noise from flaring, radiation also follows the Inverse Square Law.

So, imagine that at 1m from the tool, radiation contact dose rates associated with one of these Am/Be sources are measured at 5 milliSieverts/hour – just 10 metres away, at the site boundary, the radiation dose rate would be just 0.05 milliSieverts/hour. To put that in perspective, every member of the UK population receives an annual dose of 2.7 milliSieverts from all background sources of radiation, or 0.007 milliSieverts per day, so site boundary dose (only whilst the Am/Be source is at the surface, mind) would be the equivalent of 1.85% of a persons yearly radiation exposure.

Which is really not a lot, sweeties.

That’s not to say operators can afford to be complacent, not at all. But it’s important to keep these risks in perspective.

Until next time xxx

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