Hi Jovie Guinto
An employee may have more than one permanent workplace.
If this is the case, all their home to work journeys are ordinary commuting, just as they would be if they had 2 jobs with different employers.
However journeys made between the 2 workplaces would be business travel where they have 2 permanent workplaces for the same employer.
You can find guidance on travel costs for offshore oil/gas workers here:
EIM67195 - Tax treatment of offshore oil and gas workers: offshore rigs and platforms: travel costs