Oklahoma IS a great place to live. The oil patch is difficult here right now & can be highly location-dependent. A water hauler down here in the Duncan area gets $19-21/hr, while up in Chickasha or Watonga might get $23+.
Crude (with a co. that owns a pipeline) & saltwater are the steadiest gigs. Working for O/Os & 3rd parties can suck though when contracts get lost and/or the work moves.