HSBC's recent forecast suggests U.S. shale oil production will keep rising for another four years before peaking, but the real story is more complex. Wood Mackenzie highlights a new era of efficiency gains in shale, yet these advancements come with significant costs that could hinder future growth. Despite last year's impressive 1 million barrels per day increase, driven by unexpected efficiency improvements, the sustainability of such gains is far from guaranteed. Shale Shocked Last year, the U.S. shale industry surprised pretty…