Plains eyes Rockies expansion as oil shippers seek more pipeline space from Canada Highlights May bring quicker access to refining, export markets Line 3, Keystone XL, Trans Mountain delays stretch on WCS discount to WTI narrows to $11.60/b Tuesday  Plains All American Pipeline launched an open season this week to gauge demand for an expansion of its Western Corridor pipeline system to move more oil from Canada, Montana and Wyoming toward refining and export markets on t