Shell is doubling down on North American gas in a major bet on long-term LNG demand, agreeing to buy Canada’s ARC Resources in a $16.4-billion deal that will add roughly 370,000 barrels of oil equivalent per day to production and strengthen the supermajor’s position in one of the continent’s most strategic gas corridors. The acquisition gives Shell access to roughly 2 billion barrels of reserves while bolstering supply feeding LNG Canada, the export project Shell operates with a 40% stake and increasingly views as a cornerstone…