As the discount of U.S. crude to global benchmark Brent nears three-year highs, an emerging bottleneck at the key storage hub in Cushing, Oklahoma, is making U.S. futures vulnerable to a drop, traders and analysts said. Infrastructure constraints in the shale-rich Permian basin have already kept U.S. oil prices below international grades. Now, new constraints threaten to depress them even further and widen the gap between U.S. West Texas Intermediate crude (WTI) and global benchmark Brent. Pipelines are overwhelmed as U.S. crude production continues to hit new highs. The bulk of the record 10.9 million barrels per day produced last week came from the Permian Basin of West Texas and New Mexico. […]