When did this fight happen? In which comic issue did Hulk rip Logan in half?
It is Ultimate Wolverine vs. Hulk The series takes place between Ultimate X-Men issues 69 and 71 and before Ultimates 2 issue 11. The miniseries is a throwback to Wolverine's comic debut in The Incredible Hulk #180-182.
In Issue one:
Wolverine awakens to find his lower half missing, his body having been ripped in half by the Hulk minutes earlier. Using his keen sense of smell, he finds his legs have been thrown to the top of a mountain. As he climbs up a mountain to retrieve his legs, he recalls the events leading up to his current situation.
In Issue three: (It actually takes place)
Hulk and Wolverine have a conversation where Hulk states that he was cured of his anger, (even though as Hulk becomes angrier during the course of the conversation he becomes less articulate) but a parting comment Wolverine makes about Betty Ross enrages Hulk and causes him to tear Wolverine in half.