Are you asking about landing on a platform or a 'rig'? A rig is a drilling set-up, which can be free-floating, towed or stationary, in place over a well.
Platforms, of whatever type: production; pipeline or bunkhouse are pretty easy to land on. Just avoid any obstacle above the deck surface. High recon, low recon on the approach I always fly a steep approach to a point sufficiently high to break away or do the slow, slow, slow vertical descent to touchdown. Fly the path your searchlight defines.
If you're asking about an drilling rig in position to service the well, the same procedure except I might have to do an into the wind (more or less) point in space aside the pad and terminate, in a slow, slow, slow vertical/sliding descent to touchdown.
Same for a rig in tow, except the point in space is moving at a couple knots which affects the speed of the final point in space.
And be really really sure the crane is locked in place, unoccupied, away from the approach and landing.
P.S. Check the flare boom isn't venting over your approach or pad.