Steven Donaldson's body was discovered in the car park at Kinnordy Nature Reserve near Kirriemuir, Angus, in the early hours of June 7 last year.
The 27-year-old from Arbroath, who had been lured to his death, was the victim of a "sustained and prolonged" attack involving extreme levels of violence, a court heard.
Callum Davidson and Steven Dickie were convicted earlier this month of murdering the offshore worker following a trial at the High Court in Edinburgh.
The pair, both 24, were jailed for life when they returned to the court to hear their fate on Thursday.
A judge ordered Davidson to spend a minimum of 24 years behind bars while Dickie was told he must spend at least 23 years in jail.
Donaldson's former girlfriend Tasmin Glass, 20, was told she would be detained for 10 years after being convicted of culpable homicide.
Passing sentence, judge Lord Pentland described the victim as a "loved and admired" young man who had established a career.
"He had many years of life to look forward to," the judge added.
Lord Pentland told Dickie and Davidson had used "extreme violence" in their attack on Mr Donaldson and that the assault was "sustained and prolonged".
"You cut him down without mercy."
He added: "What I am left with is a clear picture - demonstrating you are both cold-blooded, violent and unrepentant."