Dispatch
In the UK and Norway, most of the operators flying in support of Oil & Gas operate just like fixed wing airlines - dual pilot, IFR with all the associated planning - each operator uses a different system, often developed in house.
They all have flight dispatchers who, in one way or another, reconcile all of the passengers & freight, board them, perform a cabin check and then pass paperwork to the crew, usually through the cockpit window trying not to drop it...
The three heliports at Aberdeen (for example) handle something like 8,500 passengers outbound each week (hopefully a similar number inbound!) and moving that number of people needs quite a ground operation.
Hope that helps.