Oil rig employment

by Nipuna
(Matara, Sri lanka)

i am a qualified class 3 marine engineer holding the c.o.c of 111/1. i have experience as 4th engineer on merchant ships for 18 months.so that gained the skills of operation and maintenance of marine diesel engines and power generators.please advise me weather i can get job on oil or gas rig. and for which rank should i apply?