OIL AND GAS FIELDS
Platforms and tanker moorings generally show all or some of the following lights:
Mo(U)W.15s 10 or 15M, Mo(U)R.15s 2M, aircraft obstruction light; 
and sound fog signals: Mo(U)30s.
Unauthorised navigation is prohibited within 500 metres of structures, and of subsea
production wells marked by buoys. 
Manoeuvring tankers should be given a wide berth.