First off, best of luck to you. Remember to stay strong.
My question is, are there any other females that you work with or that are in that profession? Could you talk to one of them? They will be able to help you way more than you might imagine. Just approach one and say, "hey, I know we don't know eachother too well, but there is something I want to talk to you about that is bugging me, but you gotta keep it confidential, ok?"
This is what I would do in your place, in fact, that is what I did--of course I was in a data entry office, not an oil rig.
If there is a female at your place you can talk with I would do this before sending out a letter.
Alea iacta est is always nice to say, but sometimes you end up wishing you wouldn't have cast the dice--or that it would have at least fallen in your favor.