Oil prices will struggle to break past $60 a barrel next year as they extend a year-long slump on continued worries over a global crude glut , major investment banks say. While U.S. shale oil production, a driving factor in that glut, has started to fall, heavyweight producers like Saudi Arabia and Russia are still pumping at near-record levels at a time when the market is anticipating new crude from Iran . As supply remains strong, demand growth is expected to weaken alongside a decline in the economy of China , the world’s No. 2 oil consumer. Next year, Brent crude, the international price gauge, will average $58 a barrel, and West Texas Intermediate, the U.S. oil benchmark, will average $54 a barrel, according to 13 banks polled by The Wall Street Journal. On Wednesday, Brent crude was trading around $48 […]