Tough game to get into as it's often the chicken and the egg scenario,won't take you on without offshore experience but how do you get it if they won't take you on!
I'm trying myself right now mate and I've even moved up to Aberdeen to try and get my name out there,I've found for someone like me the chances of getting straight off are slim,zero without survivex (the course you need ) and slim without compex (which you may have being involved with mines anyway) so I'm off to work in an oil company onshore then try my luck that way,often they send you offshore to check the products etc so you get experience that way,do a few trips and that's you then.
Type in Aberdeen press and journal into t'internet and see what's out there,if your involved with hydraulics then you stand an excellent chance.
Oilcareers is another good site and try Carlton resourcing for a top notch agency in Aberdeen.
There's tons of info out there if you keep trawling but it's still very hard to get into,but worth it,there's fuck all else paying those wages and offering so much time off.