Depends on the job.
There aren't very many expats here, at the moment at least, working in petroleum exploration or production, that I know if. I know Chevron used to have an office here, but it consisted of a couple of guys and a couple of secretaries.
It also depends on the posting.
Guys who work in places like Nigeria, for example, got a 40% danger bonus when posted there in the company I worked for. Drilling engineers, also, are very scarce. Seems like there's never enough. High demand, high danger - high pay.
But like I mentioned previously, without knowing the actual job or posting it is difficult to know if that's a reasonable salary.
My boss at the drilling company I worked for, who was the Director of IT, made around $200K a year before stock options. Upper-middle management, and non-operational. He rarely stepped out of his office except for meetings and such, except one time he did meet me in Aberdeen to check up on progress of a refitting project we were working on...