I can't comment on Al Waha, but I have worked for another oil company.
The usual shift rotation is 6 and 3, but for safety it was 4 and 4. The first and last days of the shift are travel days.
By and large the Libyan people working for the oil companies are well educated and motivated. They have Mediterranean work habits, but they do get the job done ... but maybe not quite up to the standards expected in the West.
Many of the functions, especially safety and mission-critical maintenance and a few specialist management functions are done by ex pats.
You will be well paid and the accommodation and catering will be basic but quite adequate. Most of the houseboys and other support staff are Egyptian. You will be very pleasantly surprised by the skill and efficacy of the top management. And you'll be frustrated at the over-close attention to pointless detail.
(I was forbidden from disposing of a class set of books from the 1980s for which the accompanying tapes were unavailable and had been out of print for almost 20 years. I also had to keep a large box of specialist headsets for a language lab which had been taken out 2 years earlier.)
Whether you enjoy it or not deepens overwhelmingly on (i) your own tolerance of uncertainty, (ii) your ability to laugh in the face of adversity and (iii) your good nature and acceptance of other people's cultures.
Of course, Al Waha may be completely different, but probably won't be.