Result of breakdown in talks aimed at keeping supplies running for three to six months.
The company has been struggling to cope with weak prices for natural gas and has a heavy debt burden.
The deal will require further regulatory clearances from the E.U., China, Australia, and Brazil.
The Bakken divestiture will reduce Hess’s 2015 capital spending to $4.1 billion from $4.4 billion.
The decision effectively means oil producers can increase output as they see fit.
Environmental groups contend harsh weather conditions make it impossible to drill in the Arctic.
Lund only took office on February 9, and is not expected to stay on at BG after the deal is completed.
The company has published accounts for last year showing an overall loss of $7.2B.
Shareholders of both companies will each own about 50 percent of the combined business.
First oil super-merger in a decade could prove to be one of the biggest deals of 2015.