How to filter a .csv file based on the integer value in one specific field (per record)

Hi, hope someone can help me (again!)
I have a large .csv file full of text & numbers.
I would like to 'filter' this file based on several 'keys', 2 text strings
(use grep I think) and the integer value of a specific field being greater
than a certain value (e.g. 100000).
I can see a way of using grep to filter on the two strings, but can't see
an elegant way of getting the numerical test on a specific field, bearing
in mind numbers occur in other fields.
The text fields I filter on are of the form ABC12 the integer from 2 to 6
digits
Hope this is clear (and not too dumb/newbie/rtfm a question) :)
.

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